RV Trailer Tires

[CWtheMan]

A synopsis: My version of RV trailer weights, tire & axle fitments simplified.

Although automotive vehicles and RV trailers are governed by the same building regulations and standards the weights may differ. The one undisputed weight is the vehicle’s GVWR. It is the maximum acceptable operating weight specified by it’s manufacturer.

Because axle manufacturers do not manufacturer axles in weight increments that will coincide with a vehicle manufacturer’s needs, the vehicle manufacturer has the authority to set GAWR weights that differ from the axle manufacturer’s certified GAWR. Example; Your trailer’s axles may have a tag on them from their manufacturer certifying their maximum load as 4000#. The trailer manufacturer can derate them to 3700#. It’s commonly done to allow the fitment of tires. In this case it could be they want to use ST215/75R14C tires because of their load capacity and diameter. Bottom line; The vehicle manufacturer’s GAWR values supersedes the axle manufacturers values and are the official certified values for that fitment.

Tires fitted to RV trailer axles must provide a load capacity equal to or greater than the certified GAWR of the axle (s). RV trailer manufacturer’s are required to set a recommended inflation pressure for those tires that is appropriate for their fitment.

Tire and axle fitments for RV trailers differ from automotive vehicle fitments because of the way the regulations and standards are written. Load capacity reserves are not a requirement for RV trailer tires or the axles they are fitted to. Their only requirement is to have load capacities equal to the tasks they are required to perform.

In the automotive industry axles and tires must provide a percentage of load capacity reserves. Their builders can do that with the axles/tire fitments or both. Look on your tow vehicle’s certification label and you will find that when the GAWRs are added together, they exceed GVWR. GVWR is the limiting factor so the axel overage is load capacity reserves. The tires may also have some load capacity reserves but not always. Rear tires may be maxed-out (inflation wise) but the axle’s load capacity reserves prevents the tires from being overloaded.

Tire industry standards for RV trailer tire replacements pretty much supports 100% of the building regulations that are certified. Because the building regulations are providing a minimum safety factor the tire industry standards will not do less. So, replacement tires must have a load capacity equal to or greater than the Original Equipment tires. That’s the way it’s written, but, there are other factors. Tire design. There are antiquated DOT regulations that are still active and are or can be applied at any time. They set a precedent that disallows changing tire designs from the trailer manufacturer’s OE tire design. It’s why it’s called a misapplication and also why almost any reputable tire retailer will refuse to make the swap. There are exceptions, LT tires designated RST (Regional Service Trailer). Any tire designed for low platform trailer service. Those are mostly 17.5” tires. Some European/Asian commercial tires designed for trailer service.

Because a trailer manufacturer uses something other than ST tires on a specific model or series of models does not imply that design can be used on some other model (s). The vehicle manufacturer has the sole responsibility in tire fitments and the tire design for such fitments. If a trailer manufacturer’s normal fitments are ST tires, with an optional design offering, that offering ends when the trailer is certified. Final certification ends before the vehicle is signed over to a consumer/owner. (Under some circumstances an authorized dealer is allowed to change the certification label prior to first sale, but only with the consent of the trailer manufacturer).

Today’s RV trailers, from the smallest to the largest, have more storage space than ever before. They can easily be overloaded long before all the storage spaces are used-up. It takes a wise and dedicated owner to be diligent enough to manage their trailer’s loads and how they are balanced.

Going back to those ST215/75R14C tires. They provide 3740# of load capacity for a 3700# axle. RV trailer axles hardly ever have a balanced load, so it’s very possible that one of those tires is going to be overloaded all the time. Only a savvy owner that often goes to a set of scales for load balancing can come close to being successful at keeping those tires from failing, early. (Early being a couple of years).

Remember, brochures are not official documents. They may have accurate information but not 100% of the time. Information in the vehicle owner’s manual is official. It was mandated by NHTSA. It should always be your guide over and above what is said in writings such as this.

I know all about what so and so said. “What is good for the goose is not always good for the gander.”

Reference material:
FMVSS
CFR 49 part 567
US Tire Manufacturing Association

[Hodgy]

.

Wow !

I did not know there were so many words about tires . . . . .

.

[Sherwolfe]

Well, this should become interesting :popcorn:

[rhagfo]

Well, this should become interesting :popcorn:

I agree, my 5er came from the factory with LT tires 235/85-16E’s, 3,042# ea capacity 12,168# total on a 32’ 5er with a GVWR of 12,360# that is plenty in my book. The originals were 12 years old when I replaced them last summer.

[Tinner12002]

Mine came with axles rated at 2K more than the GVWR and with tires rated at 5480# more than GVWR, so figure that one out...not complaining though!

[notanlines]

Okay, I'll start it.
"The originals were 12 years old when I replaced them last summer."
I'm not sure I would have admitted this.

[rhagfo]

Okay, I'll start it.
"The originals were 12 years old when I replaced them last summer."
I'm not sure I would have admitted this.

Why not? They were LT's still in very good shape, always covered and the last couple of years most of our trips were about 150 miles.
I see so many post on here of those running ST tire get a blowout thinking back to maybe hitting a curb, or a bad set of tracks. Heck these tires did this many times and still preformed great.
So many on this site are so happy to get a set of ST tires for their 5er and pay less then $400 for a set of four, then bitch like crazy when one blows after a year of service. I paid over twice that for a quality set of LT same size and weight capacity as the OEM LT tires.
I see all this talk of the ST being "Special" to deal with the scuffing when turning. Well I don't buy that, had a neighbor that ran log truck for years, ran the same casings, be it be steer, drive, or trailer position. When drivers got worn a bit and still had ok tread depth, but traction was down, those were moved to trailer position, then when tread was worn out, they were capped. Could be capped for either drivers or rib tread for trailer use.

Just my personal experience.

[CWtheMan]

Mine came with axles rated at 2K more than the GVWR and with tires rated at 5480# more than GVWR, so figure that one out...not complaining though!

Keystone has always been better with fitments for triple axle trailers. There is probably money involved with your trailer's axle, wheel & tire fitments. Those ST tires are much less expensive than the 16" LRG RST tires or the 17.5" tires used for such fitments before the strictly Asian 16" LRG tires hit the market.

Does your trailer's certification label list your axles as 7000# GAWR? Just curious. Usually RV trailer builders do not want to invite consumers to overload the trailer's GVWR.

[IRV2]

My tires are rated 2540# each single. My axles are 4400# and my GVWR is 10,000# seems like I need more axle:ermm:

[CWtheMan]

Why not? They were LT's still in very good shape, always covered and the last couple of years most of our trips were about 150 miles.
I see so many post on here of those running ST tire get a blowout thinking back to maybe hitting a curb, or a bad set of tracks. Heck these tires did this many times and still preformed great.
So many on this site are so happy to get a set of ST tires for their 5er and pay less then $400 for a set of four, then bitch like crazy when one blows after a year of service. I paid over twice that for a quality set of LT same size and weight capacity as the OEM LT tires.
I see all this talk of the ST being "Special" to deal with the scuffing when turning. Well I don't buy that, had a neighbor that ran log truck for years, ran the same casings, be it be steer, drive, or trailer position. When drivers got worn a bit and still had ok tread depth, but traction was down, those were moved to trailer position, then when tread was worn out, they were capped. Could be capped for either drivers or rib tread for trailer use.

Just my personal experience.

Going back in Keystone's tire fitment history you will find that in model years 2005 & 2006 they fitted all 6000# axles with LT235/85R16E tires. Mostly Missions from China and Uniroyal's by Michelin. As the off shore ST tire manufacturer's adapted to the USA market, more sizes and increased load capacity ST tires were built and saturated the RV trailer market. Keystone, like most all other RV trailer manufacturer's took advantage of the cost difference and started using all ST tires in 2007.

This is a fact. No tire manufacturer of any design would ever recommend their tires to be used beyond 10 years. Also, most recommend professional annual inspections from the 5 year point forward.

Because Keystone fitted LT tires to a lot of their models does not mean individuals can do the same. You cannot find a LT tire with the load capacity of a like sized ST tire. Example, LT235/85R16E has a maximum load capacity of 3042# @ 80 PSI. ST235/85R16E has a maximum load capacity of 3640# @ 80 PSI. Since 2007 the prefix ST & LT are part of the tire's size.

The wording in the tire fitment standard the trailer builders must abide is such that it avoids monetary or brand consideration. It goes like this: "The size designation and the recommended cold inflation pressure for those tires such that the sum of the load ratings of the tires on each axle is appropriate for the GAWR." Remember, all the builder has to do is meet the minimum safety standard, the vehicle certified GAWR (s). If you get more than that, consider it a gift of load capacity reserves.

Once understanding how and why particular words are used in regulations/standards written in government documents it becomes clear why in the paragraph above "appropriate" also means that the recommended inflation pressures are also minimal. That is supported by the tire industry as they say to never use less tire inflation pressure than what is recommended on the tire placard. REF: US Tire Manufacturer's Association.

[rhagfo]

My tires are rated 2540# each single. My axles are 4400# and my GVWR is 10,000# seems like I need more axle:ermm:
Total 5er is 10,000#, less 20% pin is 8,000# on the axles. axles are rated for 8,800# total, tires 10,160#, I don't see the issue.

My tires on my 5er have a total capacity of 12,168# on a 12,360# GVWR. 12,360# - 20% = 9,888 so plenty of tire capacity on LT's.

[rhagfo]

Going back in Keystone's tire fitment history you will find that in model years 2005 & 2006 they fitted all 6000# axles with LT235/85R16E tires. Mostly Missions from China and Uniroyal's by Michelin. As the off shore ST tire manufacturer's adapted to the USA market, more sizes and increased load capacity ST tires were built and saturated the RV trailer market. Keystone, like most all other RV trailer manufacturer's took advantage of the cost difference and started using all ST tires in 2007.

This is a fact. No tire manufacturer of any design would ever recommend their tires to be used beyond 10 years. Also, most recommend professional annual inspections from the 5 year point forward.

Because Keystone fitted LT tires to a lot of their models does not mean individuals can do the same. You cannot find a LT tire with the load capacity of a like sized ST tire. Example, LT235/85R16E has a maximum load capacity of 3042# @ 80 PSI. ST235/85R16E has a maximum load capacity of 3640# @ 80 PSI. Since 2007 the prefix ST & LT are part of the tire's size.

.............

You are correct that the ST have a higher load RATING, personally I don't trust that rating!
I want tires on my 5er that I can treat the same way as the LT tires I run on my TV. Where an accidental curb brush, or driving 70 on the interstate, is going to put them at risk.

On Edit: I am amazed that many think manufactures can build a stronger tire for way less money than a tire rated to carry less for longer and far less blowouts.

[CWtheMan]

My tires are rated 2540# each single. My axles are 4400# and my GVWR is 10,000# seems like I need more axle:ermm:

If you deduct the trailer manufacturer's recommended tongue/hitch weight from the trailer's GVWR you will have the weight the axles are required to carry.

I found these specs for your trailer;

GVWR: 9940
Hitch: 1390

This is how the standard is written;

"The sum of the GAWRs of all axles on the vehicle plus the vehicle manufacturer's recommended tongue weight must not be less than the GVWR."

REF: FMVSS 571.120 paragraph S10.2

[CWtheMan]

You are correct that the ST have a higher load RATING, personally I don't trust that rating! (It's sort of a brand thing. Some off shore ST tires get above average reviews from around the forums).
I want tires on my 5er that I can treat the same way as the LT tires I run on my TV. Where an accidental curb brush, or driving 70 on the interstate, is going to put them at risk.

On Edit: I am amazed that many think manufactures can build a stronger tire for way less money than a tire rated to carry less for longer and far less blowouts.

A lot of the money difference is in tariffs our government allows the off shore manufacturers to enjoy.

Tire manufacturers are required to list the basic building materials on each tires sidewall. It's basic and will not include sizes or anything other than basic materials such as polyester/nylon. Everything else is confidential. However, every DOT certified tire used on our highways must have a letter of certification on file with the DOT. That letter of certification must include testing results for strength.

This is not a plug, it's fact. The new USA built ST tires do have sidewall scuff protectors and nylon overlays.

On another note. Trident is bringing China tire manufacturing to the USA (NC).

[Tinner12002]

Keystone has always been better with fitments for triple axle trailers. There is probably money involved with your trailer's axle, wheel & tire fitments. Those ST tires are much less expensive than the 16" LRG RST tires or the 17.5" tires used for such fitments before the strictly Asian 16" LRG tires hit the market.

Does your trailer's certification label list your axles as 7000# GAWR? Just curious. Usually RV trailer builders do not want to invite consumers to overload the trailer's GVWR.

Yes, they are listed as 7K axles on cert. I also quizzed them about the fact I had a 19K GVWR with 21K axles and 24.4K on tires. What the keystone rep, not salesman, told me was as long as I didn't exceed the axle rating on overall weight I was good to go, but...if for some reason I was weighed and I was over the 19K then sorry about my luck! With everything I'll load including both bikes I can stay around 20.5K so I'm going to say I'm good with that, maybe not for weight police but for my equipment.

[IRV2]

Ok I see 1390-10000=8610 axels are 8800 then per spec sum of axles 8800 plus hitch 1390 is 10190 and that is more then my GVWR.

Where on my trailer is this hitch/pin weight?
And how do we accurately measure our pin weight?

[Tinner12002]

Ok I see 1390-10000=8610 axels are 8800 then per spec sum of axles 8800 plus hitch 1390 is 10190 and that is more then my GVWR.

Where on my trailer is this hitch/pin weight?
And how do we accurately measure our pin weight?

You can get pin weight by weighing your truck as its ready to tow, then hook up your RV, pull on the scales with only your truck, record that #, then if you want a GCW then pull it all, truck and RV onto the scales, record that #, then, pull truck only off of scales with RV still hooked up, record that # and that will get you what you have on your RV axles. Then to get pin weight take your truck # with RV attached and subtract truck only #, the very first one you got before you hooked up your RV and that is your aprox pin weight. Hopefully I explained that to be easily understood. Other than what the manufacturer estimates your RV pin weight to be which may or may not be accurate, weighing it as I mentioned is the only way to get pin weight as its not listed on the RV.

[IRV2]

You can get pin weight by weighing your truck as its ready to tow, then hook up your RV, pull on the scales with only your truck, record that #, then if you want a GCW then pull it all, truck and RV onto the scales, record that #, then, pull truck only off of scales with RV still hooked up, record that # and that will get you what you have on your RV axles. Then to get pin weight take your truck # with RV attached and subtract truck only #, the very first one you got before you hooked up your RV and that is your aprox pin weight. Hopefully I explained that to be easily understood. Other than what the manufacturer estimates your RV pin weight to be which may or may not be accurate, weighing it as I mentioned is the only way to get pin weight as its not listed on the RV.
Ok that makes sense got it thanks.

[CWtheMan]

Ok I see 1390-10000=8610 axels are 8800 then per spec sum of axles 8800 plus hitch 1390 is 10190 and that is more then my GVWR.

Where on my trailer is this hitch/pin weight?
And how do we accurately measure our pin weight?

The manufacturer's published pin weight is a pre-sale vehicle certification requirement weight. It's no longer valid once a consumer/buyer takes control of the vehicle. The new owner is 100% responsible for the trailer's weight and balance.

I've done a math evaluation of a lot of Keystone models. Their recommended pin weights are - percentage wise - within safe parameters. However, they are set on the most ideal balance.

[CWtheMan]

Ok that makes sense got it thanks.

The generic Keystone owner's manual gives brief info on how to get your hitch/pin weight. It's on page 21.

http://www.keystonerv.com/media/5212943/keystone_owners_manual_2018.pdf

[srvnt]

Goodyear has the only ST tire manufactured in the USA, and so far they are awesome after about 10,000 miles. No more foreign bombs for me.

[Hodgy]

Goodyear has the only ST tire manufactured in the USA, and so far they are awesome after about 10,000 miles. No more foreign bombs for me.


That is what I am putting on the TT in the spring.


.

[jsmith948]

Goodyear has the only ST tire manufactured in the USA, and so far they are awesome after about 10,000 miles. No more foreign bombs for me.The Carlisle tires I put on my Cougar were made in the US.

Sent from my HTC6525LVW using Tapatalk

[notanlines]

I was under the impression that Carlisle tires were made off shore. However I haven't owned them for years. I wonder what state they are located in.....

[srvnt]

The Carlisle tires I put on my Cougar were made in the US.

Sent from my HTC6525LVW using Tapatalk

A pic of your Carlisle sidewall tires would convince me.

[jsmith948]

A pic of your Carlisle sidewall tires would convince me.Well, I would have to drive to Tucson (where I traded the trailer) to do that.
You are entitled to doubt my veracity. It makes little or no difference to me.

Sent from my HTC6525LVW using Tapatalk

[srvnt]

Well, I would have to drive to Tucson (where I traded the trailer) to do that.
You are entitled to doubt my veracity. It makes little or no difference to me.

Sent from my HTC6525LVW using Tapatalk

I wouldn't call it doubt, just want the facts. I found on their website a $50.00 USA Trail that was said to be made in the US but can't verify from any pics on the site. That stamp is proof, not words even from the maker imho. Most peeps here go with the imported Carlisle HD Trail. I researched extensively and i either missed it or these are new tires so I went with the Goodyear Endurance. I hope folks have good luck with them I hope they work out great. #MAGA

[CWtheMan]

It’s been many years since I’ve seen Carlisle trailer tires with manufacturing plant codes from any USA plant. I’ve seen code 8L on them in the past indicating a plant located in Trinidad. Most recently their HD series have a code A0 for a China plant. I cant find a USA plant code for Carlisle that builds ST tires.

However, it’s quite possible their newest tires may have been moved to a TN plant to have the newest available for their affiliation with the BASS organization. When I attend the big local fishing show in a few months I'll make a special point to get plant codes from the Carlisle ST tires used for hauling those big bass boat rigs. Maybe in the meantime someone here will purchase the newest ones and provide us with a plant code. It would be nice to confirm someone is competing in the USA with GY.

[ChuckS]

Geo Star 574 G. 14 ply, G rated .. load capacity 3750 at 110 psi. Been on my fifth wheel for 3 seasons of use. Very good LT tire for heavier fifth wheels. It works and gets the job done.


Sent from my iPhone using Tapatalk

[CWtheMan]

Geo Star 574 G. 14 ply, G rated .. load capacity 3750 at 110 psi. Been on my fifth wheel for 3 seasons of use. Very good LT tire for heavier fifth wheels. It works and gets the job done.


Sent from my iPhone using Tapatalk

I don't have an older reference for Geostar but I'm pretty sure their G574 LRG LT tire was a RST - regional service trailer - tire. (A sort of GY G614 knock-off)

The newer G574s are now ST tires with more load capacity.

[ChuckS]

I don't have an older reference for Geostar but I'm pretty sure their G574 LRG LT tire was a RST - regional service trailer - tire. (A sort of GY G614 knock-off)

The newer G574s are now ST tires with more load capacity.



I believe your right. I’ve been very pleased with these as the cost is quite a bit less than G614s. I tow at 62 and after third season I’m hoping for maybe two more seasons of use. Tires are covered all the time to minimize UV degradation


Sent from my iPhone using Tapatalk

[JRTJH]

Not to change the topic, but for those who haven't yet changed out the air in their tires, summer air has expired and it's time to prevent problems. Winter air is free at almost every compressor, so don't wind up like this, change your air soon !!!!!

[sourdough]

Not to change the topic, but for those who haven't yet changed out the air in their tires, summer air has expired and it's time to prevent problems. Winter air is free at almost every compressor, so don't wind up like this, change your air soon !!!!!


Wow! What a timely reminder! I just did that today. Took me a couple of hours to deflate all the tires and get fresh winter air into the compressor but got er done. Thanks John.

[JRTJH]

My pleasure, Danny. It's not as critical for you folks down in Florida, but with the "crispness" up in this part of the tundra, it's nearing "crisis mode" :angel:

I did mine back in November during a particularly chilly day, so I'm set until spring. Those who do it tomorrow will really get some good "winter air" for their tires :whistling:

[ctbruce]

Don't forget to top off your blinker fluid too. You don't want to run out. EBay has a great deal on synthetic, recommended for all cars.https://uploads.tapatalk-cdn.com/20171224/9d8230a9086e98e829abd7a4e23f37bb.jpg

Sent from my SAMSUNG-SM-N910A using Tapatalk

[66joej]

Great suggestion but up here in the frozen North we use the winter air year round. Just one less job to do!

[Hodgy]

.

Glad I had my winter air in, this morning it was -25c or -12F for those South of 49?

.

[Ken / Claudia]

Thanks CW for taking the time to write this thread. As, I have said before the trailer tires are one of the most important safety items on the trailers and mostly overlooked and not understood.
This last year 2 of my friends were taking fishing boats to the coast both I was helping them get the boats ready. Both had old tires and 1 also had under inflated tires, 1 had cracks all over the side walls both using ST tires. Either knew anything about ST tires, both trailer tires had most of the tread on them so, they said there OK. Heck they never had any problems, SO FAR. 1 blew a tire on the trip to the coast. The other on the next trip. I explained to them the tires are rotten and will blow up. It was not important to either until the failure.

[CWtheMan]

During our Navy years we lived at Virginia Beach, VA for 7 years. Until then I’d been a Bass fisherman but got hooked on the great salt water fishing available in the Chesapeake Bay. So, I traded my bass boat for a big deepvee and a dual axle trailer. It was an inland boat and after the 1st year I had to replace the rotted trailer for a galvanized one. We almost always put-in at the boat ramp at the Navy base at Little Creek. There was a great free fresh water wash down area adjacent to the boat ramping area. It just prolonged the effects the salt water. Then I got a galvanized one and it lasted until I got transferred to FL where I went back to bass fishing.

I learned a lot about how to take care of tires in salt, brackish and fresh water. The effect of nicks in the sidewalls or between the treads will cause them to rot from the inside, out. The salt and brackish water will ruin a damaged tire really fast because it will also eat the steel belts just about as fast as the other cording materials. Galvanized wheels and stainless steel bolts are the best preventative to prolong axle life. After our first year with the galvanized trailer and it’s galvanized wheels we had learned to change tires regularly. Even though we inspected the tires after washing we still changed them every 9-12 months. We kept the best ones for spares. Even back then we were using ST tires. They didn’t cost much and it was a lot easier to change all at once rather than one or two at a time on the side of the road. We never went out of the area so they never saw speeds above 55 MPH.

Our two boys were teens back then and we had some wonderful times drift fishing for flounder or tying-up to the bay-bridge tunnel at markers 10-15 and catching Blues, Gray Trout or an occasional lunker striper (just to name a few).

[gearhead]

Yes CW, saltwater boats require a bit more maintenance. I just put 5 new Carlisle HD's on my 4 year old boat trailer. It gets washed down after every trip, either at the car wash or more likely in my driveway with my pressure washer. I hit it with the leftover Salt Away after I use that in the outboard. I open all storage doors and let it sit out in the sun to dry before storing in the garage. So far no issues.
I sometimes tow it 2 hours on interstates and I really don't want to be on the side of I-10 before dawn changing a tire.

[CWtheMan]

In post #10 of this thread I made reference to the fact that the prefix letters (P=Passenger, LT= Light Truck & ST=Special Trailer) have officially become part of the tires size designation.

Just recently the Rubber Manufacturers Association (RMA) was reorganized and is know known as The Tire Manufacturers Association.

While browsing thru some of their PDF files about RV tires - looking for changes - I came across this very interesting paragraph.

“Replacement tires should be the same as the OE size designation, or approved options, as recommended by the vehicle or tire manufacturer. Never choose a replacement tire of a smaller size or with less load-carrying capacity than the OE tire size at the specified vehicle tire placard pressure.”

[CWtheMan]

RV trailer tire inflation pressures:

A very controversial subject and one that often gets posters angry with my comments. I’m pretty convinced that the anger is caused by the abundance of antidotal information written on the subject. “My retailer and friend for years says this, my dad never had a flat doing this, the charts say otherwise,” and on and on.

The information I’m going to post here is strictly from tire industry regulations and tire manufacturer’s standards. Right up front I’m gong to say this, The correct tire inflation pressures for your Original Equipment (OE) RV trailer tires is found on the trailer’s certification label, in the vehicle owner’s manual and on the tire placard. Why? Because it’s on the certification label and that label provides minimum safety information.

So, how was the recommended tire inflation for my tires determined? The tire size was selected to provide, at the minimum, the necessary load capacity to support the maximum load capacity of the GAWR axle it was fitted to. The trailer’s manufacturer was then directed by government standards to set a recommended cold inflation pressure that was appropriate for those tires. The trailer manufacturer is allowed to use the inflation pressure molded on the tire’s sidewall for maximum load capacity or an inflation pressure that will support the maximum permissible load carried by the GAWR axle. Probably 97% of all recommended cold inflation pressures found for RV trailer tires are going to be set at their maximum load capacity. The OE tires must be able to support the maximum load the trailer can carry.

Is there a provision where the tire’s inflation pressures can be lowered closer to a load being carried? The tire industry has found that they cannot trump, so to speak, the vehicle manufacturer’s recommended inflation pressures. When push has come to shove, again so to speak, the tire industry has always lost any argument in that area. So, they are very consistent in their inflation pressure recommendations, even with replacements. Here it is, in part - some of them may say it differently but it will mean the same thing - NEVER use less tire inflation pressures than what has been recommended on the vehicle’s certification label. Replacement tires should be the same size designation as the OE tires or others recommended by the vehicle manufacturer or tire manufacturer. The replacements must provide a load carrying capacity equal to or greater than the OE tires, by inflation.

For those that want more information that is from valid tire industry documents, I suggest you read chapter #4 of the reference provided below. After all is said in that document, the nearly last line, or bottom line statement will refer you right back to nearly the first statement. NEVER use less recommended inflation pressure than what has been recommended by the trailer manufacturer.

https://www.ustires.org/sites/default/files/CareAndService_PassengerAndLightTruckTires.pdf

[CWtheMan]

double post.

[CWtheMan]

Tires: Tire industry standards about replacements.

There is a lot of anecdotal information floating around about replacement tires for RV trailers. Most owner’s just wing it for one reason or another. My habit is to post about what is supposed to happen. All other factors considered, it’s the safest thing to do.

In the 2017 Keystone generic RV trailer owner’s manual there is a section about tires. It was mandated to be there by the governing body, DOT. Within that information is a caution about size. Here is the actual wording from page #19 and below is the reference.

“To maintain tire safety, purchase new tires that are the same size as the vehicle’s original tires or another size recommended by the manufacturer. Look at the Tire and Loading Information label, or the sidewall of the tire you are replacing to find this information. If you have any doubt about the correct size to choose, consult with the tire Dealer.”

http://www.keystonerv.com/media/5212943/keystone_owners_manual_2018.pdf

Because I’m posting about tire industry standards here is a quote from a major contributor to those standards, Michelin.

It’s an industry standard, you can find it in all industry SOP documents.

“Never choose a tire that is smaller in size or has less load-carrying capacity than the tire that came with the vehicle. Tires should always be replaced with the same size designation — or approved options — as recommended by the vehicle manufacturer. The correct tire size designated for your vehicle should always be verified with the information in your vehicle owner’s manual or on the tire information sticker.”

https://www.michelinman.com/US/en/help/how-to-choose-tires.html#tab-4

[cathcartww]

Just my two cents ......

My personal opinion is that the industry standard “ST” tire standard is inadequate for the service the ST tires are exposed to. My opinion is based only on my own personal experience, and anecdotal experience of others.
Back in the late 1970’s through the early 1980’s, I was a boat dealer, and we towed all kinds of boats – from 19 footers weighing 2500 lb on a single axle trailer, up to 15,000 lb 30 footers on triple axle trailers - up and down I95 between New Jersey and Florida. We always used the bias ply trailer tires that were available at the time. We would carry plenty of spares, but seldom, if ever, had a problem that could not be traced to a road hazard or axle-bearing-wheel-suspension problem.
Back in the day of cotton tire cords, tires were rated by how many plies they had – the more plies, the stronger the tire, and higher load range. If I remember correctly, 2 ply was A, 4 ply was B, 6 ply was C etc. When nylon and polyester came along to replace cotton, it was twice as strong, so a fewer number of plies was needed to make a tire of the same strength. We saw labels such as 2 ply/4 ply rating, 4 ply/8 ply rating, etc.
Still later, Michelin figured out how to make radial ply tires using steel belts, and that really changed things, but the industry stuck to the “ply rated” terminology even though bias plies were no longer used.
Somewhere during this, the overall quality of trailer tires seemed to deteriorate – I personally do not think a modern day load range “D” ST radial tire holds up anywhere as well as the 4 ply/8 ply rated bias trailer tires we used 40 years ago.
On the other hand, we do seem to ask more of our ST trailer tires as we do our car and truck tires. For instance, here are my three personal vehicles, using the maximum axle rating for each – I know none of them are really running at the maximum most of the time, but I bet the Ford and trailer are close when we are towing:
1995 Chevy G20 Van, front 3400lb, rear 3406lb, running 31x10.5R15LT LR C Tires rated 2270lb @ 50psi – they are loaded at about 75% capacity.
2002 VW Beetle, front 2183lb, rear 1588lb, running 205/55R16 91H tires rated 1356lb @ 44psi – they are loaded to about 80% capacity.
Ford E350 Van, front 4600lb, rear 5360lb, running LT285/75R16 LR E tires rated at 3750lbs @ 80psi – they are loaded to about 71% capacity.
2015 Outback 277RL, 4400 lb axles, came with ST225/75R15 LR D tires Chinese tires rated at 2540lbs @ 65psi – they were loaded to 86% capacity
We blew on of the LR D tires last winter – no obvious hazard, and pressures were OK 150 miles earlier – go figure. We replace them with Maaxis LR E rated at 2830lb @ 80psi, so they are loaded at about 77%, which is more in line with the other vehicles.
Since then, it was time to replace the Maaxis, and we went with the newer to the market Goodyear Guardians LR E. The have the same ST weight designation as all the other ST tires, but have a higher speed rating, so at least they seem to exceed, not just meet the ST specification.
Hoping for the best, but sure wish there were more commercial trailer tires available in 15” !!

[CWtheMan]

RV Trailer Tires & Hot Brakes: It’s a subject hardly ever mentioned in forums about trailer tires. I’m sure it’s a cause for many unexplained tire failures but I only have my experiences to fall back on.

Trailer brakes often get overheated in the hilly and mountainous areas of the country. Most owners don’t check their tire temps when making stops at rest areas or fueling stops. If the brakes, wheels, and tires are clean they may not smoke unless they are dangerously overheated so no one looks at them.

It’s best to check the tire temps upon stopping and then again before you leave the area and continue on down the road. Overheated brakes will dissipate their heat into the wheel and finally into the tire. A sure sign of overheating is a tire that is warm when first checked and extremely warm 15 minutes later. The heated tire will deteriorate which may cause it to fail, normally throwing it’s tread.

Personally I check my brake controller before hitting the road, every time. If I find hot tires at a rest stop I don’t travel on them until they have returned to a normal temp. If I find just one hot tire I first determine if it’s properly inflated. If so, I continue on to see if the brake is dragging.

[flybouy]

RV Trailer Tires & Hot Brakes: It’s a subject hardly ever mentioned in forums about trailer tires. I’m sure it’s a cause for many unexplained tire failures but I only have my experiences to fall back on.

Trailer brakes often get overheated in the hilly and mountainous areas of the country. Most owners don’t check their tire temps when making stops at rest areas or fueling stops. If the brakes, wheels, and tires are clean they may not smoke unless they are dangerously overheated so no one looks at them.

It’s best to check the tire temps upon stopping and then again before you leave the area and continue on down the road. Overheated brakes will dissipate their heat into the wheel and finally into the tire. A sure sign of overheating is a tire that is warm when first checked and extremely warm 15 minutes later. The heated tire will deteriorate which may cause it to fail, normally throwing it’s tread.

Personally I check my brake controller before hitting the road, every time. If I find hot tires at a rest stop I don’t travel on them until they have returned to a normal temp. If I find just one hot tire I first determine if it’s properly inflated. If so, I continue on to see if the brake is dragging.

Agree. I keep an inexpensive infrared thermometer in my truck door. I do have a TPMS on TV and trailer but find the information from the ir thermometer essential. At every stop I turn on the 4 way flashers (I travel with headlights on when towing) I start at driver side front of truck and measure at the center of the wheel, at the rotor ( brake drum on trailer) and the tire sidewall near the tread. This will isolate the heat generating areas. Check clearance lights on my way. Stop at the hitch and check all connections and take a temp reading on coupler as well. As I work my way around to the passenger side look at tail lights and repeat the process. The simple check takes maybe 3 minutes at most. I can hold my bladder that long for the peace of mind it gives me.

[JRTJH]

I do the same as flybouy and I leave the truck idling while I do my checks. I feel this is VITAL to turbo health. Cutting off a hot turbo will "cook the oil" in the bearings and lead to early turbo failure. Every Owner's Manual I've ever read warns to idle the engine after heavy use to allow the turbo to cool down prior to engine shutdown. In fact, some truck brands offer an optional "engine idle program" that allows you to remove the key and the truck will automatically shut down after a specific time elapses.

It just makes sense (to me, anyway) to let the turbo cool down, check the tires, lights and security of hitch and all accessories (awning, slides, bumper, doors, etc) at every stop.

[Hodgy]

.

flybouy and JRTJH, you both have good process. I would like to think there are more of you out there. Having said that, I know there are some out there and others who are lacking.

Through forums such as this I hope the people who visit gain a bit of knowledge and start thinking of what can, and does go wrong.

.

[notanlines]

We also keep our now infamous el-cheapo Harbor Freight infrared thermometer handy and use it on both the actual tread of each tire and on the center of each wheel at every stop. When I do my walk-around every morning is the time that I check all lights.

[flybouy]

I do the same as flybouy and I leave the truck idling while I do my checks. I feel this is VITAL to turbo health. Cutting off a hot turbo will "cook the oil" in the bearings and lead to early turbo failure. Every Owner's Manual I've ever read warns to idle the engine after heavy use to allow the turbo to cool down prior to engine shutdown. In fact, some truck brands offer an optional "engine idle program" that allows you to remove the key and the truck will automatically shut down after a specific time elapses.

It just makes sense (to me, anyway) to let the turbo cool down, check the tires, lights and security of hitch and all accessories (awning, slides, bumper, doors, etc) at every stop.

JRTJH I omitted that part of the process but I also let it idle. At rest stops the DW goes potty while I do my walk around. Then I walk the 2 Brittney Spaniels. By that time she returns and I go to the relief station ( we use the camper's, one of the things we liked is the outside bathroom door, easy access ). Then we're back on the road, everyone refreshed!
Edit - forgot to mention but if the road was particularly rough or winding I'll open the front door and have a look see to make sure things are where they belong. Don't want a partially dislodged tv mount or can of beans to become a ping pong ball inside. Maybe it's overkill but I look at it protecting my investment .

[CWtheMan]

About keeping the selling dealer honest about cargo weights at Pre Delivery Inspections (PDI).

My information here is dated from the major Federal Motor Vehicle Safety Standards (FMVSS) rules changes dated 2007.

There is a lot of anecdotal information about RV trailer cargo loads and how they are measured. The safety standards are quite explanatory about cargo and who is responsible for it’s accuracy up until the unit changes hands from the dealer to the consumer. References FMVSS 571.110 & 571.120 are a must read for those most interested. Placards and their locations are described in 49 CFR part 567 (certification). All of those references have brief descriptions about how the numbers are applied.

Probably the most often misquoted information is about propane and batteries. Anything that is installed at the factory is accounted for with the trailer’s Unit Vehicle Weight (UVW) when it leaves the factory. That includes propane systems and the weight of full bottles/storage tanks. All water weight is cargo. If a dealer installs a battery (s) there is no adjustment to the cargo unless the battery (s) weighs more than 100# or they are combined with other equipment (options) that together weigh more than 100#.

When a unit is on display and has had no options added since it left the factory it’s weight information (UVW) should be correct. However, if the dealer has added options, the proper term for the trailer’s weight at that time is Gross Vehicle Weight (GVW). Dry weight is a term used before 2007 and would be the same as UVW.

I strongly recommend browsing the references 110 & 120. They give specifics about placard locations and how they are to be modified by the dealers. You don’t have to read the whole document. The cargo info starts at about paragraph S10 in both documents. Just type their basic number (571.120) into your computers search engine. The law document may be easier to read but the government document is official.

So, what has all that to do with tires? Weight, excessive, causes tires to go BOOM.

[CWtheMan]

RV Trailer Hitch/Tongue weight:

Because the trailer manufacturer publishes a recommended hitch/tongue weight it generates questions about it’s validity. Mostly from new owners.

It is a valid recommendation. With extreme care in balancing the trailer’s cargo loads, the recommended hitch/tongue weight will work. If it could not be balanced out, the trailer manufacturer wouldn’t be allowed to certify the trailer until it was worked-out.

So the recommendation is not hypothetical. It’s just not practical once you get the trailer home and start loading it. Only the owner knows what they are going to carry as cargo for each trip they make and they are sure not going to load to a tongue weight ever time they move the trailer. So, a ballpark figure needs to be established. It comes from experience and how the owner loads the trailer. After a few times at the scales or with your own tongue scale you can get the average tongue weight you carry.

You might ask, why does the trailer manufacturer publish a hitch/tongue weight? It’s a mandatory weight requirement they must use to ensure the GAWR axles have the necessary load capacity to support the trailer’s GVWR. In simple terms it goes like this. The published hitch/tongue weight, when added to the trailer’s total certified GAWR weight (s) must equal GVWR.

[CWtheMan]

Tire Plant codes:

Not long ago I made a statement about where Carlisle RV trailer tires were manufactured. Some have reported them being built in the USA again. I still haven't found a plant in the USA that builds Carlisle tires.

Today I went to the local boat show where there were numerous boat trailers with Original Equipment Carlisle tires. I checked 14", 15" & 16" plant codes, some were bias ply. All had plant code AQ = CARLISLE TIRE & WHEEL CO. LTD. MEIXIAN, GUANGDONG, CHINA.

If anyone purchases new Carlisle tires with a USA plant code on their sidewalls, please post the code.

[CWtheMan]

RV tires and “R” ratings

The “R” ratings I’m referring to are limiting factors as in GAWR & GVWR. I know, there’s another one, but I’m not going to mention it here.

RV trailer manufacturers, sometimes, just don’t pay attention to what their doing. Probably because the folks that design - set the limits - don’t talk to the administrators about standards and regulations. Keystone - others too - has had it’s shear of recalls for inaccurate vehicle labeling. Most of those recalls have been about weights and tires or both.

The vehicle manufacturer is solely responsible for establishing and setting the “R” factors. Once they decide what their going to build they must set minimum limits mostly based on weakest link factors. The GVWR is the ultimate limiting factor and all other weights and measurements for the trailer must fit into that limited box, so to speak. Once the GVWR has been established and affixed - certification label - to the trailer for delivery to the consumer or dealer it can only be changed or modified by the vehicle manufacturer or a certified vehicle modifier.

Axle manufacturers don’t make and certify their axles in all weight ratings trailer manufacturer’s may require. So then the vehicle manufacturer has the authority to set their GAWR values to suit the trailer’s fitment requirements. I’ve seen keystone set 5200# Dexter axles to a GAWR of 5080# just so they could fit two 2540# max load capacity tires to those axles. Remember, bottom line, tires fitted to RV trailer axles are not required to have any load capacity reserves. RV trailer manufacturer’s have always taken advantage of that fact. It might be a moral violation but it’s not a legal violation. And, don’t rely on the tag on the axle to be a true representation of it’s authorized load capacity.

Information in the above paragraph causes a lot of misconception about trailer tire fitments. Some people take the time to read the fitment standards the trailer manufacturer MUST follow and assume the can do likewise. The standards are just what they say they are, builders standards, not at large standards. When the trailer manufacturer affixes the certification label the trailer they have sworn, so to speak, to the DOT, that the trailer meets all minimal safety standards, meaning that their tire fitments are appropriate. The tire industry will not violate that minimal standard and the Original Equipment tire fitments will always be the benchmark for all subsequent replacements. To deviate from the OE tire fitments requires an agreement between the vehicle owner and the trailer manufacturer for optional fitments. Normally, a load range increase within a tire’s size designation (ST205/75R14) is not considered “plus sizing”. It’s the same tire with increased load capacity - if available.

I’ve probably mentioned this before but it’s worth mentioning again. The fitment for automotive tires, sort of like the ones on your tow vehicle, are governed from the same standard as RV trailer tires but with a twist. They are required to provide load capacity reserves via excess load capacities above the vehicle’s GAWRs and set by the vehicle manufacturer. They will normally be fitted to axles that have load capacity reserves above the vehicle’s GVWR. Also, provisions have been made via collaborations between vehicle & tire manufacturer’s that allow - with adjustments - interchangeability of Passenger and Light Truck tires for many of the vehicles you tow with. There is no such collaborations for any sort of interchangeability between tire designs for RV trailers. That takes us back to vehicle certification and the standards which allow the vehicle manufacturer to fit what they consider appropriate tires, to the vehicle of what ever highway certified tires they see fit to install. Because they did it to model #1 does not allow others to do it to model #2. The benchmark gets in the way.

You will find some statements every now and then about passenger tires not being allowed on RV trailers. That’s not so. The standards outline the procedure to be used for such fitments.

Oh well, I may have rambled too far. If you got this far and have questions just chime in.

[Hodgy]

.

CW, had to read that twice. Good bit of information in there.

Thanks . . . . .


.

[CWtheMan]

RV Trailer Wheels - Rim Sizes - Load Capacities

According to FMVSS, the wheels provided as Original Equipment on your trailer were approve by the tire manufacturer for such fitments. In fact, every tire manufacturer must provide retailers/OEM providers with a listing of wheel/rim sizes acceptable for fitment for every tire size the manufacturer provides for wholesale/retail sales.

Wheels for RV trailers must have a zero offset.

OE wheel fitments must provide a load capacity equal to or greater than the GAWR axle (s) maximum load capacities listed on the trailer’s certification label.

Wheel PSI limits are determined by the PSI capacity of the valve stem. In other words, a wheel with a 2830# load capacity must have a valve stem rated at 65 PSI or higher. The wheel’s certified load capacity is it’s ultimate load carrying limit.

Tire manufacturers build tires to fit specific wheel/rim sizes. They may build them with an acceptable width range for fitment purposes, such as 5.5” - 7.0“. They will normally determine a measuring size to use for tire specifications when fitted to that size, in this case maybe 6”, then all specifications for the tire will be consistent with the measuring rim size. Sometimes tires are unique in bead construction as in steel cased tires. Such tires may have a single rim width. That width is critical for proper tire fitment to the wheel rim. Some tire manufacturers will list a single rim width on the tire’s sidewall to assist the tire installer in selecting the proper wheel/rim size.

The big problem for RV trailer axles and the wheels & tires fitted to them is overloading. The trailer may scale out at or under GVWR but the axles may have an overweight problem. The problem is normally from a severely unbalanced condition that causes the axles to be carrying a combined load within their capacity but not evenly. One end may be 300#-400# heavier than the other end. The tire and wheel in that overloaded condition have a higher probability factor for failure.

[CWtheMan]

This has nothing to do with official regulatory standards. It is a huge organization making a stance for more reserve load capacity provisions for original tire fitments to RV trailers.

https://www.moderntiredealer.com/article/726233/new-rv-industry-standard-will-drive-a-shift-to-radial-st-tires

[CWtheMan]

About 15 years ago Goodyear introduced a - what I call - hybrid 16" trailer tire known as the G614. It had a LT prefix and was dubbed RST for Regional Service Trailer. It had/has a maximum load capacity of 3750# @ 110 PSI.

Not long after the G614 became a very successful replacement tire, the "off shore" tire manufacturer's jumped on-board and started building their brand that mimicked the G614.

With RV trailers getting larger & larger the "off shore" people developed newer ST designs with load capacities suited for the 7000# & 8000# axles on the largest RV trailers.

Not to be outdone, Carlisle has now introduced their 16" LRG all steel tire line-up with the two most popular sizes.

https://www.carlislebrandtires.com/our-products/product-detail/csl-16

I'm not plugging the brand, I have never used Carlisle tires on my RV trailer. However, Carlisle is popular with many on this forum so I've posted their info in the reference above.

Looking back, you'll find that Carlisle was one of the first trailer tire builders that foresaw the need for more load capacity for the 6500# - 7000# axles and developed 16" LRE & LRF ST tire sizes to meet the needs. Their ST235/85R16E has a load capacity of 3640# @ 80 PSI and the same tire in a LRF has a 3960# load capacity @ 95 PSI.

For a long time Carlisle recommended a speed limit of 60 MPH for their trailer tire line-up. Today, all of their Radial trailer tires are rated at 75 MPH or higher.

[CWtheMan]

Greenball has added a 15" steel cased trailer tire to it's line-up. See the reference below.

http://www.greenball.com/catalog/All-Steel-Construction.pdf

[FlyingAroundRV]

From a lot of the posts here, it seems that the tires fitted to new trailers are regarded as "China Bombs" and generally not to be trusted.
We will be picking up our new trailer in late May and I'm considering putting better tires on it right from the start as a blowout and trailer damage would be a disaster for the type of travel we do (flying over from Oz and operating from NFA).
The tires fitted as original to our trailer (Outback 272UFL) are shown as ST205 / 75 R14D. I've looked for a LRE tire in that size and haven't yet found one.
My questions are:
1) For a trailer with a max loaded weight of 7600#, is a D rating sufficient?
2) Can I use a ST225 / 75R14E on the trailer?, if so
3) What are the possible complications of doing that?
And just BTW, I was looking at Discount Tire's website and they list tires with a D1 rating. What does that mean and where can I find the weights that go with the load range ratings?
TIA

[CWtheMan]

From a lot of the posts here, it seems that the tires fitted to new trailers are regarded as "China Bombs" and generally not to be trusted.
We will be picking up our new trailer in late May and I'm considering putting better tires on it right from the start as a blowout and trailer damage would be a disaster for the type of travel we do (flying over from Oz and operating from NFA).
The tires fitted as original to our trailer (Outback 272UFL) are shown as ST205 / 75 R14D. I've looked for a LRE tire in that size and haven't yet found one.
My questions are:
1) For a trailer with a max loaded weight of 7600#, is a D rating sufficient?
2) Can I use a ST225 / 75R14E on the trailer?, if so
3) What are the possible complications of doing that?
And just BTW, I was looking at Discount Tire's website and they list tires with a D1 rating. What does that mean and where can I find the weights that go with the load range ratings?
TIA

Your tires, at LRD, are above average for 3500# trailer axle fitments. They provide more than the desired 10% load capacity reserves when inflated to 65 PSI. There are no higher load capacities for that tire size.

I don't know how the trailer manufacturer's warranty works over there. Here, in the USA, the trailer manufacturer would have to recommend the 15" tires as optional fitments for there to be full trailer warranty coverage. Over here they are not going to do that.

[FlyingAroundRV]

Your tires, at LRD, are above average for 3500# trailer axle fitments. They provide more than the desired 10% load capacity reserves when inflated to 65 PSI. There are no higher load capacities for that tire size.

I don't know how the trailer manufacturer's warranty works over there. Here, in the USA, the trailer manufacturer would have to recommend the 15" tires as optional fitments for there to be full trailer warranty coverage. Over here they are not going to do that.
Thanks for that info.

In fact the trailer will stay in the US, we have no plans to transport it back to Australia. And that is the reason why preventing a tire blowout and subsequent trailer damage is so important to us. While we are touring the US for 3-4 months at a time, the trailer will be our home, we will be essentially full-timers. So anything that lays the trailer up for a significant period of time or causes damage that I cannot repair myself, means the end of our holiday and a huge complication to get sorted by remote control from back here in Oz.

So just to be clear;
Are you saying that a ST225 / 75 R14E would not be suitable for those wheels?

And finally, where could I find the info on the weight capabilities of the tires by load range?
Thanks again.

[busterbrown]

Thanks for that info.

In fact the trailer will stay in the US, we have no plans to transport it back to Australia. And that is the reason why preventing a tire blowout and subsequent trailer damage is so important to us. While we are touring the US for 3-4 months at a time, the trailer will be our home, we will be essentially full-timers. So anything that lays the trailer up for a significant period of time or causes damage that I cannot repair myself, means the end of our holiday and a huge complication to get sorted by remote control from back here in Oz.

So just to be clear;
Are you saying that a ST225 / 75 R14E would not be suitable for those wheels?

And finally, where could I find the info on the weight capabilities of the tires by load range?
Thanks again.

My 2017 Bullet 308BHS was fitted with tires sized ST205/75/14C. In order to go up two load ratings, I invested in new 15 inch wheels that would accommodate LRE tires. You'll have to do the same as I don't think an LRE exists (with any brand) in a wheel size of 14 inches.

Each manufacturer will usually have a web link to the specs on each of its brand. These are 4 that I quickly searched on.

Carlisle Radial Trail HD (https://www.carlislebrandtires.com/our-products/product-detail/radial-trail-hd)
TBC Brands Trailer King II (http://trailerkingtires.com/tires/Landing.aspx?application=trailerking2-product-line)
Maxxis ST Radial M8008 (https://www.maxxis.com/catalog/tire-122-129-st-radial-m8008)
Goodyear Endurance (https://www.goodyear.com/en-US/tires/endurance/sizes-specs)

On a side note, I did see that Keystone has now increased the tire load range on its 2018 model of the 308BHS. Fitments are now ST205/75/14D. Correction of fitment after 5 years of production was way over due.

[CWtheMan]

Thanks for that info.

In fact the trailer will stay in the US, we have no plans to transport it back to Australia. And that is the reason why preventing a tire blowout and subsequent trailer damage is so important to us. While we are touring the US for 3-4 months at a time, the trailer will be our home, we will be essentially full-timers. So anything that lays the trailer up for a significant period of time or causes damage that I cannot repair myself, means the end of our holiday and a huge complication to get sorted by remote control from back here in Oz.

So just to be clear;
Are you saying that a ST225 / 75 R14E would not be suitable for those wheels?

And finally, where could I find the info on the weight capabilities of the tires by load range?
Thanks again.

I'm pretty sure the ST215/75R14D is the highest rated 14" ST tire you'll find. If your current wheels are certified for 65 PSI they will work for this larger tire providing they fall within the rim width range of 5.5" - 7".

Here is a load inflation chart for many of the ST sizes. Load inflation charts are standardized and are applicable to all brands as long as they are the same size and design.

https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

NOTE: The ST215/75R14D is .5" wider and .6" taller than the ST205/75R14D.

[Eastham]

What ever happened to just throwing some stuff in the camper and taking off and enjoying yourself.if you have to pack that much crap to go camping that you are over loading the truck and the trailer and the tires .it's to much work stay home or load less and enjoy your self. Life is to short to sweat all this small crap .Good night and lighting up.

[FlyingAroundRV]

I'm pretty sure the ST215/75R14D is the highest rated 14" ST tire you'll find. If your current wheels are certified for 65 PSI they will work for this larger tire providing they fall within the rim width range of 5.5" - 7".

Here is a load inflation chart for many of the ST sizes. Load inflation charts are standardized and are applicable to all brands as long as they are the same size and design.

https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

NOTE: The ST215/75R14D is .5" wider and .6" taller than the ST205/75R14D.
Thanks for that. I don't know where I came up with the ST225/75R14E and haven't been able to find it again. Must have been my old eyes tricking me

[FlyingAroundRV]

What ever happened to just throwing some stuff in the camper and taking off and enjoying yourself.if you have to pack that much crap to go camping that you are over loading the truck and the trailer and the tires .it's to much work stay home or load less and enjoy your self. Life is to short to sweat all this small crap .Good night and lighting up.
Yep, that's what we want, just relaxed touring. It's not that we intend to overload our trailer, more that we want to be sure (as possible) of trouble free touring.
If you've been following the thread, you'll know that we live in Australia, but are buying a TT and truck to tour in the US. If something major goes wrong, we might end up having to sort it out by email and snail mail and telephone calls from Oz. Not a happy prospect, but one we're prepared to gamble on if we can stack the odds in our favor.

[ctbruce]

Yep, that's what we want, just relaxed touring. It's not that we intend to overload our trailer, more that we want to be sure (as possible) of trouble free touring.
If you've been following the thread, you'll know that we live in Australia, but are buying a TT and truck to tour in the US. If something major goes wrong, we might end up having to sort it out by email and snail mail and telephone calls from Oz. Not a happy prospect, but one we're prepared to gamble on if we can stack the odds in our favor.Even more important, I feel you're doing your best to make sure your time here is trouble free and not tied up needlessly with your trailer or rig sitting in a shop. I get it. You get special compensation over the rest of us Homer's here in the states full time.

[sourdough]

What ever happened to just throwing some stuff in the camper and taking off and enjoying yourself.if you have to pack that much crap to go camping that you are over loading the truck and the trailer and the tires .it's to much work stay home or load less and enjoy your self. Life is to short to sweat all this small crap .Good night and lighting up.


I used to just "throw stuff" in the camper, in the bed of the truck, in a trailer or anything else and just go. I never, ever worried about loading. Even bought a shop built slide in that I put in a new '69 Chevy C10. Sort of like some of us; put on overloads, add a leafs, heavy duty shocks trying to help the truck. It still swayed to no end. Then, in 1983, after doing just that (throwing cut logs for firewood into a 16' trailer not paying attention or worrying) I almost went over a 200' cliff because the load in the trailer pulled the front of my truck up enough I couldn't steer into the curve. I had been stupid, in a hurry and never paid a second's notice that we had overloaded the front of the trailer. Looked pretty good....but, nope. That was the worst incident I've ever experienced that I wasn't knocked unconscious and thankfully woke up......in a hospital, pool of blood etc......you get the drift.

So, now, although it is more fun to just "throw it in" and go without a care in the world, I care (not meaning that anyone else doesn't)....and I worry leaving me with no option but to look at weight limits and weight that I add to most anything. A phobia I guess:banghead:

[notanlines]

What ever happened to just throwing some stuff in the camper and taking off and enjoying yourself.if you have to pack that much crap to go camping that you are over loading the truck and the trailer and the tires .it's to much work stay home or load less and enjoy your self. Life is to short to sweat all this small crap .Good night and lighting up.

I gave serious thought to picking up the stick and poking it through the fence, but I didn't think the dog would be sharp enough to even get upset.....:facepalm:

[CWtheMan]

Tire load and inflation standards are developed by three different organizations. North American, European, and Japanese.

Here I’m just going to be mentioning those from the North American Tire & Rim Association (TRA).

The charts are standardized. All tires of the same size and construction can use a chart from any manufacturer of that tire. For this discussion I’m just mentioning Special Trailer (ST) tires, Light Truck (LT) tires and Passenger (P) tires. All of those are highway tires and approved by the governing body (NHTSA) for trailer axle service, when approved for that fitment by the vehicle manufacturer. An approved tire size is like this; ST225/75R15 or LT235/85R16 or P175/50R15. A load range, load index, or speed letter in a tires suffix are not part of the basic size.

For our vehicles built under the guidance of the Federal Motor Vehicle Safety Standards (FMVSS), the need to use any of the charts is minimal. The FMVSS instructs the vehicle manufacturers to set an appropriate recommended cold inflation pressure for all vehicles they build and certify. Those recommendations are the minimum standard and none in the tire industry will recommend using less than what the vehicle manufacturer has set and certified on the individual vehicle’s placards for the Original Equipment (OE) tires.

Tires on our motorized vehicles provide a percentage of load capacity reserves and their recommended cold inflation pressures are almost always less than what is required for the tires maximum load. In those conditions the difference in recommended inflation pressure and tire maximum load pressure is an optional area. Some vehicles, such as pick-up trucks may even have vehicle manufacturer recommendations for the use of higher inflation pressures when the vehicle is being used for towing another vehicle.

We often see forum posters recommending tire inflation for the load being carried. The major fault with that is two fold. It’s a no-no to use less inflation pressure than what has been recommended by the vehicle manufacturer. And, inflation to the load carried may need to be adjusted every time you use the vehicle. One PSI inflation pressure below the load carried is a loss of about 1.6% of its load capacity. Heat generation for being under inflated comes to mind.

In these forums, everyone posting about replacement tires seems to have a different idea of how it’s supposed to be done. The tire industry wide rule is to always use replacement tires that are the same size as the tires that came on the vehicle. It’s a very complex explanation as to why it’s a misapplication to use tires that do not match the design of the Original Equipment tires and I’m not going to try and explain it here. This is about tire inflation charts.

Plus sizing is a very popular option many seek when replacing their RV trailer tires. It’s where the tire inflation charts are most needed and part of their basic design is to assist the installer of plus sized tires. Here again, is another tire industry standard that applies to plus sizing your tires. They MUST provide a load capacity equal to the load capacity provided by the OE tires at the vehicle manufacturer’s recommended cold inflation pressure. What that means, when looking at your tire placard you will find the OE tires size and their recommended cold inflation pressure. Now it’s time to find a tire inflation chart for that particular tire. From the chart you can find the load capacity the tire is providing at the trailer manufacturer’s recommended PSI. Let’s say the tire size is ST205/75R14 and had a load range letter of D with a recommended 65 PSI. So, from the chart we find that it’s providing 2040# of load capacity. There is not a LRE in that tire size so you’ll have to ask the vehicle manufacturer about a larger tire for replacement. We all know their answer. If the larger tire was never offered as an option for that trailer they are going to tell you to use another tire just like the ones that came on the trailer. They fitted the OE tires and said they were an appropriate fitment for that trailer and are going to stand with that original decision. To do otherwise would put them in a situation of decision reversal, they’re not going to do that.

So, now you’re going to have to do some decision making. Normally a smallish tire dimensional size change can work on RV trailer axles. Even those closely spaced. A 10% increase in tire load capacity is a ballpark figure to look for. The ST215/75R14 is the best fit. It will fit the OE wheels. It’s just .6” taller & .5” wider. The owner would have to make sure there is sufficient wheel well clearances. At 65 PSI the 215 will provide 2200# of load capacity. Looking at the tire inflation chart for the 215 tire shows a load capacity of 2120# @ 60 PSI.

A normal step for the installer to perform, is to identify the different sized replacement tire. For that purpose, NHTSA approves the use of an auxiliary tire placard. On it, the installer can put the new tire size and from a tire inflation chart for that tire size, a recommended cold inflation pressure that insures the tire will provide as much load capacity as the OE tire did at the vehicle manufacturer’s recommendation. The AUX placard can then be placed adjacent to the original tire placard. Then a notation should be made in the vehicle owner’s manual.

There really is no need to fool around with RV trailer tire inflation pressures. Only a very few owners travel enough to ever see their trailer tires wear out. They are age-out tires.

Our RV trailers have a very different center of gravity than our motorized vehicles. Trailers tend to fish-tail, bob and weave and travel in an unbalance condition most of the time. All tires are designed to safely operate at their maximum load capacity.

What many trailer owners do not consider is the load on their tires. (Probably the most damaging thing a new trailer owner does to their tires is over load them. Fill-up the water tank, get all the stuff in the basement and other storage areas and hit the road. POP - BANG). Trailers are built to minimum standards for their maximum allowed loads. The tires are not required to have any load capacity reserves. Even when you load your automotive vehicle to it’s limit it still has tire load capacity reserves. It’s part of the fitment differences between automotive and trailer tires.

You want full life expectancy from your trailer tires? Give them 10% - 15% in load capacity reserves.

[CWtheMan]

What seems like a long time ago, Probably about 15 years, I started researching ST tires. At that time there were very few tire manufacturers building the ST tires. The largest and most well known was Carlisle. They saturated the industry with information about their ST tires and were probably the most prolific OEM provider for at least 5 years. (There was also a new and upcoming ST tire builder, Goodyear. They, for a time, overtook Carlisle as leading OEM provider. Then, there was/is CHINA).

When large tire retailing chain stores started stocking Carlisle ST tires, Carlisle provided them with oodles of information about their tires and how they differed from other highway tires.

Carlisle said ST tires could degrade by as much as 10% a year. They had and still have one of the shortest warranty periods of all ST tires. Carlisle recommended their tires be used at 60 MPH or less (TRA sets unmarked ST tires at 65 MPH). Carlisle recommended their tires to be operated at the inflation pressure molded into the tire’s sidewall (that’s for MAX load capacity). Carlisle was very stern about their ST tires life expectance saying 3-5 years was the maximum regardless of mileage.

In interviews with information outlets line Modern Tire Dealer, Carlisle spokespersons would spout out their recommendations and ST sellers/users took notes. Almost everything you read about ST tires in Discount Tire’s on-line publications are excerpts from Carlisle PDFs. So, their recommendations became the norm.

ST tires on today’s market have come a long way from where they started. But, don’t get me wrong. I’m not against max pressure for ST tires. It’s almost always recommended by the vehicle manufacturer’s and when that’s the case the max is also the min. But, that’s not so for replacement tires with excess load capacity. The canned answer from the replacement tire rep will be to use what is recommended by the vehicle manufacturer. So use as much extra load capacity as you are comfortable with. Most of the time it’s not going to be the 110 PSI the tire needs for max load. 90 or 100 PSI may provide the extra load capacity you need for excess load protection and a better ride.

Just about every ST tire now purchased has a speed rating of 75 MPH or higher. Every MPH you travel under the tires speed rating provides a little more protection from overheating a tire when it’s close to its maximum load. Before the higher speed ratings all we had was 100% inflation protection at 65 MPH.

Back to the Carlisle thing. If you did not archive any of their old PDF forms you’re out of luck. Their new ST tires are up-to-date and in line with all other ST manufacturer’s and with speed letters in the 81 MPH range. At a recent BASS fishing show the only tires close to outnumbering the Carlisle’s were Passenger tires. A lot of the large dual axle rigs really liked the low profile passenger tires. (RV trailers and boat trailers are built to the same FMVSS standards, the vehicle manufacturer decides what fitment is appropriate).

[CWtheMan]

One thing the China tire manufacturers have shown us is their ability to rapidly enter new tire designs and sizes into the market places.

Here are the specs for the all steel Carlisle trailer tire.

ST235/85R16 Carlisle CSL 16 Radial Trailer Tire (14 Ply)
The CSL 16 from Carlisle is an all steel radial trailer tire. The CSL 16 was specially built with heavy duty carrying ability for large equipment and heavy loads. With a heavy duty all steel casing, the CSL 16 offers larger carrying capacity than you typical trailer tire. CSL 16 tires are designed to provide long service life and dependable performance.

Manufacturer: Carlisle Tire
Manufacturers Part Number: 6H08111
Load Range: G
Ply Rating: 14 Ply
Mounted Diameter: 31.7 inches
Mounted Width: 9.3 inches
Recommended Rim Width: 6.50 inches
Alternate Rim Width:
Max Load Capacity Single: 4400 lbs
Max Load Capacity Dual: 3850 lbs
Max Pressure: 110 psi
Tread Depth: 11.6 (32nds)
Speed Rating: M
Max Speed: 81 mph
Tire Weight: 50 lbs


I'll post more brands and sizes whenever I find they are available in the USA market places.

Because I post information like this does not mean I'm supporting brands. Other manufacturers are building these tires and have been for some time. There are also some 15" all steel tires being built with a LRF that have a 3195# load capacity @ 95 PSI. Greenball has them in their line-up in size ST225/75R15 and is touting them in their Towmaster brand.

[FlyingAroundRV]

Quote CWtheman
"CSL 16 tires are designed to provide long service lifeand dependable performance. "
This appears to be an interesting concept in the realm of trailer tires. From all that I read, trailer tires perish before they wear out. So what is the definition of "long sevice life"? I don't know what the average yearly mileage a trailer tire would do, but it seems by all accounts that the rubber hardens, cracks and decays long before the tread is worn out, on most "average use" RVs.
Currently, my TT has the "China bombs" that came with it. I expect that next year, when I return to use the trailer after 9-odd months storage, I may have to put a new set of tires on the trailer. Even at $150/ tire, we're not talking a lot of money.
Are we over-thinking this?

[sourdough]

Quote CWtheman
"CSL 16 tires are designed to provide long service lifeand dependable performance. "
This appears to be an interesting concept in the realm of trailer tires. From all that I read, trailer tires perish before they wear out. So what is the definition of "long sevice life"? I don't know what the average yearly mileage a trailer tire would do, but it seems by all accounts that the rubber hardens, cracks and decays long before the tread is worn out, on most "average use" RVs.
Currently, my TT has the "China bombs" that came with it. I expect that next year, when I return to use the trailer after 9-odd months storage, I may have to put a new set of tires on the trailer. Even at $150/ tire, we're not talking a lot of money.
Are we over-thinking this?

I agree. I think the term "long service life" from the manufacturer is relative to their concept of trailer tires. "Long service life"? 3 years instead of 2 or ??? Trailer tires being what they are I don't think any ST tire manufacturer has put out a tire that shatters the norm for the type tires they are. Now, if we're talking about tires from Shandong province, yes, most anything can shatter their record (china bombs).

[CWtheMan]

To view the entire document you can put; 49 CFR Part 567, in your search engine.

I mention the vehicle certification label in many of my tire posts. Lot’s of owner’s view the label as just another meaningless bit of information and others never even take the time to find it’s location on their trailer.

When the trailer manufacturer completes the building process, the final step before shipment to an owner or dealer is to verify and certify that the vehicle meets ALL federal motor vehicle standards. That’s a bold statement and not only did they make it to you, the owner, they did likewise to the DOT.

Below I have used logic to form the opinion.

On the certification label your will find the tire size and recommended cold inflation pressures to assure those tires meet the requirements of the trailer’s GAWRs. Because FMVSS are written to insure minimum standards are met, those tires and inflation pressures are the minimum requirement for that trailer. To use anything less would be a safety violation. Now, I’m just a tire researcher, what do I know, right? Well If I can figure that out, how long do you think it would take an experienced litigator to do so?

[CWtheMan]

“The RV Industry Association is the national trade association representing RV manufacturers and their component parts suppliers who together build more than 98 percent of all RVs produced in the U.S., and approximately 60 percent of RVs produced worldwide.”

RVIA has mandated changes in Original Equipment (OE) tire load capacity recommendations and design upgrades that are probably already showing-up on all new RV trailer models that display their RVIA membership placard.

IMO, any RV trailer manufacturer member that wants to remain a member is going to comply with RVIAs recommendations.

The basics are very simple. All RV trailer tires larger than 13” in OD must be radial designed tires.

RVIA recommends RV trailer manufacturer’s provide a 10% load capacity reserve, above the certified GAWRs for all OE tires. That means, a RV trailer with 3500# GAWR axles must have tires that that can provide 1925# of load capacity when inflated to the trailer manufacturer’s recommended cold inflation pressures found on the vehicle certification label.

I hope anyone that has a 2018 or later model RV trailer with a RVIA placard, will challenge the validity of their OE tires, if they do not meet the new RVIA standard.

There are a lot of bias ply tires still available from wholesalers. The RVIA bias ply tire recommendations do not include replacement tires. The recommendation is not legally binding in any way. Therefore, they can still be used as replacements for any tire fitments above 13” OD. They are much less expensive than radials. For those that only travel locally and only a couple times a year, they are the most economical solution.

Remember, RVIAs recommendations are in no way binding on the RV trailer industry. There is nothing to prevent the vehicle manufacturer from just leaving the RVIA seal of approval off the trailers they manufacturer. The vehicle manufacturer is still free to use the FMVSS without any government repercussions.

[sourdough]

“The RV Industry Association is the national trade association representing RV manufacturers and their component parts suppliers who together build more than 98 percent of all RVs produced in the U.S., and approximately 60 percent of RVs produced worldwide.”

RVIA has mandated changes in Original Equipment (OE) tire load capacity recommendations and design upgrades that are probably already showing-up on all new RV trailer models that display their RVIA membership placard.

IMO, any RV trailer manufacturer member that wants to remain a member is going to comply with RVIAs recommendations.

The basics are very simple. All RV trailer tires larger than 13” in OD must be radial designed tires.

RVIA recommends RV trailer manufacturer’s provide a 10% load capacity reserve, above the certified GAWRs for all OE tires. That means, a RV trailer with 3500# GAWR axles must have tires that that can provide 1925# of load capacity when inflated to the trailer manufacturer’s recommended cold inflation pressures found on the vehicle certification label.

I hope anyone that has a 2018 or later model RV trailer with a RVIA placard, will challenge the validity of their OE tires, if they do not meet the new RVIA standard.

There are a lot of bias ply tires still available from wholesalers. The RVIA bias ply tire recommendations do not include replacement tires. The recommendation is not legally binding in any way. Therefore, they can still be used as replacements for any tire fitments above 13” OD. They are much less expensive than radials. For those that only travel locally and only a couple times a year, they are the most economical solution.

Remember, RVIAs recommendations are in no way binding on the RV trailer industry. There is nothing to prevent the vehicle manufacturer from just leaving the RVIA seal of approval off the trailers they manufacturer. The vehicle manufacturer is still free to use the FMVSS without any government repercussions.

Thanks CW!! Very useful information. I would encourage every prospective buyer/owner to read the information in red and double check that on any trailer you are thinking about buying. There seems to be a line at the upper end of travel trailers and the smaller/mid size 5vrs where tires are really skimped on. I don't recall seeing any trailer I've looked at that didn't have the RVIA sticker on it so chances are that whatever you are looking at (new) will have it. If so, the above would come into play and could certainly be useful.

[CWtheMan]

There seems to be a bit of misunderstanding here. The Federal Motor Vehicle Safety Standards (FMVSS) are a mandatory safety net, written by the National Highway Traffic Safety Administration (NHTSA) to insure all vehicles - including all RV trailers - are built in compliance with minimum safety standards.

The final step a RV trailer manufacturer must do before it leaves the factory is certify that all those standards have been met.

Minimums and maximums are confusing to many owners. Especially with tire fitments.

First I’m going to establish a couple of facts.

The axles on your trailer may have two GAWR values. The axle manufacturer builds and certifies their axles to a weight value. It is defined as its Gross Axle Weight Rating (GAWR). The axle manufacturer is required to display that weight rating on each individual axle and the do so with a tag attached to each axle. Here’s the catch. Vehicle manufacturers have the authority from NHTSA to set GAWR values below the axle manufacturer’s values. Therefore, the official GAWR values for any RV trailer can only be found on its federal certification label. A common setting found on many older Keystone RV trailers was for axles manufactured with a 5200# rating from their manufacturer to be de-rated by Keystone to 5080#. They did that so they could mount tires rated at 2540# on those axles. That’s just one example. Numerous 7000# axles were also de-rated to accommodate Marathon tires that were rated at 3420#. That’s just some of the minimums Keystone complied with.

The standard for determining a RV trailer’s GAWRs has always been determined by the maximum weight it has been designed to carry, as determined by the vehicle manufacturer, in accordance with minimum standards set by FMVSS. Remember, the build target is the GVWR. To establish a trailer’s GAWRs the vehicle manufacturer does this simple math, which is a mandatory step in vehicle certification. They must set a recommended tongue/hitch weight. When that hitch weight is added to the total vehicle certified GAWR values they must not be less than GVWR. It’s the only time that tongue weight will be used unless an owner can perform the magic needed to duplicate it with a balanced load in their trailer. The weight difference between GVW and GVWR is cargo. Again, you must remember, the trailer GVW is not sitting on the tires. A percentage is always setting on the tongue/hitch of the tow vehicle or its landing gear.

Original Equipment (OE) tire selection for your RV trailer is driven by FMVSS and is the sole responsibility of the vehicle manufacturer. First and foremost is the absolute minimum standard, to provide a load capacity that will support the maximum load capacity of the vehicle certified GAWR axles. The bottom line is a provision in the FMVSS that reads - in part like this; The size designation and the recommended cold inflation pressure for those tires such that the sum of the load ratings of the tires on each axle is appropriate. The word appropriate at the end of that statement establishes the fact that the OE tires are the minimum requirement for that fitment and all subsequent replacements must have a load capacity equal to that fitment.

Recently, The Recreational Vehicle Industry Association (RVIA) has made a recommendation for all RV trailer tires to have, at the least, a 10% load capacity reserve above the trailer’s GAWR. IMO most RV trailer manufacturer’s will do just that and add the increased cost to them to the consumers.

Something to consider when researching tire safety is your trailer’s owner manual. Everything about tire safety found in those manuals are there in accordance with NHTSA mandates.

When linking standards and regulations to form a conclusion, don’t forget to add CFR 49 part 567 (Certification) to your list of references.

Here is a sample of a research topic. They all say it a little differently but the bottom line is the same. It’s a tire industry standard driven by a FMVSS minimum standard.

Goodyear: Never fit tires to a vehicle that have less load carrying capacity than required by the Original Equipment Manufacturer.

Michelin: Never choose a tire that is smaller in size or has less load-carrying capacity than the tire that came with the vehicle.

Cooper: The new tires must have a load carrying capacity equal to or greater than the maximum load carrying capacity specified on the tire placard on the vehicle.

Toyo: Any replacement tire must be of a size and load range that will offer equal or higher load carrying capacity compared to the original equipment (OE) tire on the vehicle.

This is another reference from the USTMA that is useful when discussing tire inflation pressures.

“Inflation pressure recommendations may be determined
based on the tire manufacturer’s specifications, which define
the amount of inflation pressure necessary to carry a given
load. These inflation pressures may differ from those found
on the vehicle tire placard or certification label.”

“However, never use inflation pressure lower than specified by
the vehicle tire placard, certification label or owner’s manual.
Nor should inflation pressure exceed the maximum pressure
molded on the tire sidewall.”

[CWtheMan]

Very good link by a tire industry writer.

https://www.moderntiredealer.com/article/410842/guilty-until-proven-innocent

[Tufelhunden]

“The RV Industry Association is the national trade association representing RV manufacturers and their component parts suppliers who together build more than 98 percent of all RVs produced in the U.S., and approximately 60 percent of RVs produced worldwide.”

RVIA has mandated changes in Original Equipment (OE) tire load capacity recommendations and design upgrades that are probably already showing-up on all new RV trailer models that display their RVIA membership placard.

IMO, any RV trailer manufacturer member that wants to remain a member is going to comply with RVIAs recommendations.

The basics are very simple. All RV trailer tires larger than 13” in OD must be radial designed tires.

RVIA recommends RV trailer manufacturer’s provide a 10% load capacity reserve, above the certified GAWRs for all OE tires. That means, a RV trailer with 3500# GAWR axles must have tires that that can provide 1925# of load capacity when inflated to the trailer manufacturer’s recommended cold inflation pressures found on the vehicle certification label.

I hope anyone that has a 2018 or later model RV trailer with a RVIA placard, will challenge the validity of their OE tires, if they do not meet the new RVIA standard.

There are a lot of bias ply tires still available from wholesalers. The RVIA bias ply tire recommendations do not include replacement tires. The recommendation is not legally binding in any way. Therefore, they can still be used as replacements for any tire fitments above 13” OD. They are much less expensive than radials. For those that only travel locally and only a couple times a year, they are the most economical solution.

Remember, RVIAs recommendations are in no way binding on the RV trailer industry. There is nothing to prevent the vehicle manufacturer from just leaving the RVIA seal of approval off the trailers they manufacturer. The vehicle manufacturer is still free to use the FMVSS without any government repercussions.
That explains why my tires, 2018 Cougar with an 8800 GVWR had the ST225/75R15 trailer king ii radials, #2830 rating.

[CWtheMan]

Just some info. Triangle is building a complete line-up of ST tires in a NC plant. Here is a link. Lots of info in each tab.

http://triangletireus.com/truck-tires/tr653/

[CWtheMan]

I’m not supporting GY one way or another with this post. I’m just going to present some information I’ve observed, first hand, and with some personal researching habits. All can be misconstrued as anecdotal except my actual experiences.

When we started full time RV travels in 2003 we purchased a 2003 Everest. It had 6000# axles and they were fitted with Goodyear Marathon trailer tires manufactured in a USA plant. They were ST235/80R16 LRD. At recommended cold inflation pressures Keystone set for them, 65 PSI, they provided 3000# of load capacity. In the beginning our trailer’s axles were carrying very close to their maximum load capacities with at least one tire being overloaded all the time. Before the scales became our friend we suffered 7 tire failures. All Marathons. After that, we went to the next higher load capacity for that sized tire, which provided us with more than 500# of load capacity reserves, per tire position, which were never above 3000# per axle end again.

I got so involved with RV trailer tire problems I got hooked on researching them. It became a sort of hobby. I got some analytical training and experiences while in the Navy. I was directly involved with the verification and validation of the maintenance manuals for the A7 Corsair II aircraft. I was formally trained and received certification as a Navy Manpower Management Analyst and worked on the staff of the Commander in Chief US Atlantic Fleet for three years. The team I was assigned to provided field support to all Atlantic Fleet Aviation Intermediate Maintenance activities. We worked in three person teams - one 05/04 one GS11/GS9 and one E9/E8 - and were on the road half of the year. The other half of the year we worked at the home office ironing out our reports.

I’m pretty sure the governing body, the Department of Transportation (DOT), got duped into a wrong assessment about how to determine the load capacity for Special Trailer (ST) tires. I’m pretty convinced that they should have followed the path taken with automotive tires and established some load capacity reserves for the ST tires. Very early on, the Rubber Manufacturers Association (RMA) - know known as the US Tire Manufacturing Association (USTMA) pushed hard for a 15% load capacity reserve above GAWR. It has never been adopted by the National Highway Traffic Safety Association (NHTSA). Without such requirements, RV trailer owners have been without any load capacity reserves for their tires from just about all trailer builders. The first to give us any clue was Carlisle. Many years ago they said their ST tires might degrade as much as 10% per year. Without any load capacity reserves, degrading guarantees tread separations on, otherwise, perfectly maintained tires.

Speed ratings were never discussed in the vehicle owner manual and even today in Keystone’s generic 2019 manual there is still no mention. What percentage of RV trailer owners knew their tires were limited to 65 MPH? Early on Carlisle recommended a maximum of 60 MPH in their PDF files for their ST tires. Today their bias ply tires have a speed letter “J” = 62 MPH.

The GY Marathon production was moved to China plants. Some thing happened, they continued to fail, back to the USA, still failing. Why they kept them in the Original Equipment Manufacturer (OEM) loop is beyond me. Trailer manufacturer’s (IMO) were screwing them. Trailer manufacturer’s get to manipulate Gross Vehicle Weight Rating (GAWR) values for any trailer they build. I’ve found Keystone trailers with GAWRs set at 5080# so they could put tires rated at 2540# on them. Travel heavy and above 65 MPH and pop in two years or less. The heavier the trailer the faster degrading happens. So they derate 7000# axles to 6850# so they can put the GY 3420# tires on them. All legal. Who pays? GY pays big time with the bad tire rep. Got a trailer with 3500# axles? Watch out for those 1760# tires, they wont last very long if you’re traveling close to axle max.

Then all of a sudden you see a China tire doing good in the ratings. No wonder, it’s not an OEM tire and is often used as a replacement with a load range increase above the OE tires. DAH!

Then you have the posters of failures that have done some homework. Everything was properly maintained but they had tread separations. Without a weight slip it’s just another anecdotal and the tire brand is at fault for sure.

If you’re going to travel heavy or think your traveling heavy or have never made a trip to some scales you’ve got to insure your tires have 100% of the inflation pressure listed on their sidewalls for maximum load capacity. You need to make it a habit to insure your tires are inflated before every trailer movement. The ballpark figure is a 1.6% loss of available load capacity for every 1 PSI loss of inflation. Any tire found to be inflated 20% below cold recommendation is considered to be in a “run flat condition”.

Class Action, Blah! There has been one collecting information for years on the Tow Max tires and it’s got nowhere. Their another high OEM usage tire getting hammered. IMO Class action is doomed without forensic support.

NHTSA needs to get hammered on this subject. RVIA has taken action. 10% is a big step over nothing. Maybe in a few years we’ll see a nice drop in ST tire failures. If not, we’ll have to get a bigger hammer.

Bottom line; I'd prefer a recall action over a proposed class action every time.

[busterbrown]

Got a trailer with 3500# axles? Watch out for those 1760# tires, they wont last very long if you’re traveling close to axle max.

Exactly the case with my coach. Factory fitments included 3,500 lb axles and 14" LRC 1760 lb tires on a 7,600 lb GVWR trailer. Only took me a few months to realize the inadequencies of the components most likely to fail. As of 2019, the tire size remains the same but Keystone is abiding by the new RVIA recommendations of 10% reserve capacity with LRD fitments on the same coach. 2040 lbs of load capacity vs 1760 lbs. Definitely a step in the right direction.

I wish these guidelines included changes to axle and suspension components too. A failed leaf spring last week on my 2 year old trailer is reason for concern. They are only rated for 1750 lbs and now become the weakest link in the underpinnings on the chassis. The axles are a close second.

[mazboy]

HERE YOU GO....the answer to all.

always go up one rating level. If an 'E' rated, go up to a 'F' or better, a 'G' rated tire.

And, inflate to the level the tire states! 'G' rated tires are 110psi.

[Javi]

HERE YOU GO....the answer to all.

always go up one rating level. If an 'E' rated, go up to a 'F' or better, a 'G' rated tire.

And, inflate to the level the tire states! 'G' rated tires are 110psi.

And that only works if your wheels are rated for the higher pressure... And in many cases the only way to do that is to swap axles or axle components to accommodate higher rated wheels..

For instance my 5200 pound axles have 16" wheels with 6 x 5.5 studs which are 80 lb. / 3200 lb. rated.. there are no 110 lb. wheels for that configuration or for that matter there are no 95 lb. wheels either. ...
Solution... Change to 7K axle components and buy new wheels for the "G" tires..

Not many folks going to do that... :D

My axles are rated 10,400 lbs. combined... My wheels are rated 12,800 lbs. and my tires are rated 13,680....

Now... where's the weak link for a trailer with 12,350 GVWR :whistling:

[Snoking]

And that only works if your wheels are rated for the higher pressure... And in many cases the only way to do that is to swap axles or axle components to accommodate higher rated wheels..

For instance my 5200 pound axles have 16" wheels with 6 x 5.5 studs which are 80 lb. / 3200 lb. rated.. there are no 110 lb. wheels for that configuration or for that matter there are no 95 lb. wheels either. ...
Solution... Change to 7K axle components and buy new wheels for the "G" tires..

Not many folks going to do that... :D

My axles are rated 10,400 lbs. combined... My wheels are rated 12,800 lbs. and my tires are rated 13,680....

Now... where's the weak link for a trailer with 12,350 GVWR :whistling:

There was a much easier solution in Michelin XPS Ribs or Bridgestone Duravis R250s. I ran RIBs in that configuration for 6.5 years, then a set of R250s for 4.5 years until the trailer was sold. Never a problem, seldom need tire added and I never looked back! Chris

[Javi]

There was a much easier solution in Michelin XPS Ribs or Bridgestone Duravis R250s. I ran RIBs in that configuration for 6.5 years, then a set of R250s for 4.5 years until the trailer was sold. Never a problem, seldom need tire added and I never looked back! Chris

Which have a rating of 12,168 lbs. combined... Once again... even if I were so inclined, what would that actually accomplish... The axles are still the weak link by almost 1800 pounds and in fact what you suggest would make the rims the strongest element.. Mounting tires which have a lesser load rating solves nothing...

[Snoking]

Which have a rating of 12,168 lbs. combined... Once again... even if I were so inclined, what would that actually accomplish... The axles are still the weak link by almost 1800 pounds and in fact what you suggest would make the rims the strongest element.. Mounting tires which have a lesser load rating solves nothing...


Because one puts tires problems behind you with either of these two tires. Lower rolling resistance, and longer thread and tire life. Chris

[CWtheMan]

Because one puts tires problems behind you with either of these two tires. Lower rolling resistance, and longer thread and tire life. Chris

I should not have to remind you of this.

https://www.michelinman.com/US/en/help/how-to-choose-tires.html#tab-4

Remember, the prefix in this designated tire size, ST235/80R16, is part of its size.

[Snoking]

I should not have to remind you of this.

https://www.michelinman.com/US/en/help/how-to-choose-tires.html#tab-4

Remember, the prefix in this designated tire size, ST235/80R16, is part of its size.

All these years later and you are still lobbying for the ST tire manufacturers.

[notanlines]

Not that CW needs any backup from me. He is, after all, "the Man." But in following his tire posts for quite some time, it seems to me that he usually just writes what the facts are as he sees them and lets the reader make their own decision. YMMV

[Javi]

Because one puts tires problems behind you with either of these two tires. Lower rolling resistance, and longer thread and tire life. Chris

See, that's the thing... I ain't got no tire problems.. underweight axles... maybe... But doing it my way and replacing my tires every two years, I got no tire problems :whistling:

[Snoking]

Not that CW needs any backup from me. He is, after all, "the Man." But in following his tire posts for quite some time, it seems to me that he usually just writes what the facts are as he sees them and lets the reader make their own decision. YMMV

Fact is most ST tires did not get the title blowmax, maypop, china bomb and/or willpop because people did not know how to use them. They have been an inferior product for years. In the last couple years is has began to change to the better with Carlisle working hard to produce a decent ST tire, Maxxis that were made in Thailand(some swear by them) and now (drum roll) the new Goodyear Endurance.

It has been a long weight with a lot of rubber left along side the road and trailers damaged.

[flybouy]

Fact is most ST tires did not get the title blowmax, maypop, china bomb and/or willpop because people did not know how to use them. They have been an inferior product for years. In the last couple years is has began to change to the better with Carlisle working hard to produce a decent ST tire, Maxxis that were made in Thailand(some swear by them) and now (drum roll) the new Goodyear Endurance.

It has been a long weight with a lot of rubber left along side the road and trailers damaged.

I think it's a result of consumer demand. The rv industry buys the junk, then over the life of the unit the consumer will typically by a better set several times. I think it may have been Maxxis that first offered a better alternative and once their market share increased Carlisle and others followed. Good old competitive Capitalism at work!

[Snoking]

I think it's a result of consumer demand. The rv industry buys the junk, then over the life of the unit the consumer will typically by a better set several times. I think it may have been Maxxis that first offered a better alternative and once their market share increased Carlisle and others followed. Good old competitive Capitalism at work!

Maxxis is still a 3 maybe 4 year tire. They dry rot and fail from time to time. Maxxis share never grew that large because they had to be special ordered in most cases.

Availability if the GY Endurance is pretty much universal across the county. Discount tire had them in stock when I junked my brand new Goodrides and sold them on CL.

[rhagfo]

“The RV Industry Association is the national trade association representing RV manufacturers and their component parts suppliers who together build more than 98 percent of all RVs produced in the U.S., and approximately 60 percent of RVs produced worldwide.”

RVIA has mandated changes in Original Equipment (OE) tire load capacity recommendations and design upgrades that are probably already showing-up on all new RV trailer models that display their RVIA membership placard.

IMO, any RV trailer manufacturer member that wants to remain a member is going to comply with RVIAs recommendations.

The basics are very simple. All RV trailer tires larger than 13” in OD must be radial designed tires.

RVIA recommends RV trailer manufacturer’s provide a 10% load capacity reserve, above the certified GAWRs for all OE tires. That means, a RV trailer with 3500# GAWR axles must have tires that that can provide 1925# of load capacity when inflated to the trailer manufacturer’s recommended cold inflation pressures found on the vehicle certification label.

I hope anyone that has a 2018 or later model RV trailer with a RVIA placard, will challenge the validity of their OE tires, if they do not meet the new RVIA standard.

There are a lot of bias ply tires still available from wholesalers. The RVIA bias ply tire recommendations do not include replacement tires. The recommendation is not legally binding in any way. Therefore, they can still be used as replacements for any tire fitments above 13” OD. They are much less expensive than radials. For those that only travel locally and only a couple times a year, they are the most economical solution.

Remember, RVIAs recommendations are in no way binding on the RV trailer industry. There is nothing to prevent the vehicle manufacturer from just leaving the RVIA seal of approval off the trailers they manufacturer. The vehicle manufacturer is still free to use the FMVSS without any government repercussions.

There was a much easier solution in Michelin XPS Ribs or Bridgestone Duravis R250s. I ran RIBs in that configuration for 6.5 years, then a set of R250s for 4.5 years until the trailer was sold. Never a problem, seldom need tire added and I never looked back! Chris

Which have a rating of 12,168 lbs. combined... Once again... even if I were so inclined, what would that actually accomplish... The axles are still the weak link by almost 1800 pounds and in fact what you suggest would make the rims the strongest element.. Mounting tires which have a lesser load rating solves nothing...

Because one puts tires problems behind you with either of these two tires. Lower rolling resistance, and longer thread and tire life. Chris

I agree with Chris, I believe you don'e need XPS or 250's, just a quality LT tire of the correct size.

My current 5er has Yokohama LT 235/85-16 E's 3,042# ea. the number that Javi pointed out. Now I have 5,200# axles for an axle capacity of 10,400# that is 1,768# over axle capacity or 17%.

I just finished a rough scaling of the 5er. I weighed the TV the day before and unfortunately I did toss some extra stuff into the TV after, Maybe 50 to 100#. This gave me a pin of about 2,600# and 10,125# on the axles. Giving me a 12,725# or 365# over the listed GVWR (may need to loose some T shirts). Even at the weight I have 2,043# of unused tire capacity or 16.8% not bad at all. This on an LT tire with a built in weight reserve, I expect to get at least six years of service from these tires without worry.

[sourdough]

I agree with Chris, I believe you don'e need XPS or 250's, just a quality LT tire of the correct size.

My current 5er has Yokohama LT 235/85-16 E's 3,042# ea. the number that Javi pointed out. Now I have 5,200# axles for an axle capacity of 10,400# that is 1,768# over axle capacity or 17%.

I just finished a rough scaling of the 5er. I weighed the TV the day before and unfortunately I did toss some extra stuff into the TV after, Maybe 50 to 100#. This gave me a pin of about 2,600# and 10,125# on the axles. Giving me a 12,725# or 365# over the listed GVWR (may need to loose some T shirts). Even at the weight I have 2,043# of unused tire capacity or 16.8% not bad at all. This on an LT tire with a built in weight reserve, I expect to get at least six years of service from these tires without worry.

Russ, you are, and have been, a prolific voice for 1) LT tires vs ST tires and 2) disregarding gvw etc. I think, personally, that you mislead those that have no idea what LT, ST, gvw, gvwr mean. You tow overweight based on your perceived beliefs on whatever it is that you think is "the truth" even if it is outside the beliefs of most folks. By your measures, everything you do has performed better than anyone else that has ever towed an RV. That's spectacular , but, that isn't the case for everyone; and I, nor many other RV owners, buy into your thoughts. Your belief (I think it is you) that because you buy a tire with a higher speed rating LT tire (106 mph?) and then drive slower gives you MORE weight rating is just.....questionable at best. Please show the specs.

[rhagfo]

“The RV Industry Association is the national trade association representing RV manufacturers and their component parts suppliers who together build more than 98 percent of all RVs produced in the U.S., and approximately 60 percent of RVs produced worldwide.”

RVIA has mandated changes in Original Equipment (OE) tire load capacity recommendations and design upgrades that are probably already showing-up on all new RV trailer models that display their RVIA membership placard.

IMO, any RV trailer manufacturer member that wants to remain a member is going to comply with RVIAs recommendations.

The basics are very simple. All RV trailer tires larger than 13” in OD must be radial designed tires.

RVIA recommends RV trailer manufacturer’s provide a 10% load capacity reserve, above the certified GAWRs for all OE tires. That means, a RV trailer with 3500# GAWR axles must have tires that that can provide 1925# of load capacity when inflated to the trailer manufacturer’s recommended cold inflation pressures found on the vehicle certification label.

I hope anyone that has a 2018 or later model RV trailer with a RVIA placard, will challenge the validity of their OE tires, if they do not meet the new RVIA standard.

There are a lot of bias ply tires still available from wholesalers. The RVIA bias ply tire recommendations do not include replacement tires. The recommendation is not legally binding in any way. Therefore, they can still be used as replacements for any tire fitments above 13” OD. They are much less expensive than radials. For those that only travel locally and only a couple times a year, they are the most economical solution.

Remember, RVIAs recommendations are in no way binding on the RV trailer industry. There is nothing to prevent the vehicle manufacturer from just leaving the RVIA seal of approval off the trailers they manufacturer. The vehicle manufacturer is still free to use the FMVSS without any government repercussions.

There was a much easier solution in Michelin XPS Ribs or Bridgestone Duravis R250s. I ran RIBs in that configuration for 6.5 years, then a set of R250s for 4.5 years until the trailer was sold. Never a problem, seldom need tire added and I never looked back! Chris

Which have a rating of 12,168 lbs. combined... Once again... even if I were so inclined, what would that actually accomplish... The axles are still the weak link by almost 1800 pounds and in fact what you suggest would make the rims the strongest element.. Mounting tires which have a lesser load rating solves nothing...

Because one puts tires problems behind you with either of these two tires. Lower rolling resistance, and longer thread and tire life. Chris

Russ, you are, and have been, a prolific voice for 1) LT tires vs ST tires and 2) disregarding gvw etc. I think, personally, that you mislead those that have no idea what LT, ST, gvw, gvwr mean. You tow overweight based on your perceived beliefs on whatever it is that you think is "the truth" even if it is outside the beliefs of most folks. By your measures, everything you do has performed better than anyone else that has ever towed an RV. That's spectacular , but, that isn't the case for everyone; and I, nor many other RV owners, buy into your thoughts. Your belief (I think it is you) that because you buy a tire with a higher speed rating LT tire (106 mph?) and then drive slower gives you MORE weight rating is just.....questionable at best. Please show the specs.

I have said that because the tire is rated for 3,042# at 106, that it has a higher reserve capacity at 60 to 70 mph. I will not exceed the tire weight rating.
I will say that a tire rated for 106 mph has better heat dissipation than a tire speed rated to 65 mph.

As to towing over the GVWR of my Ram, it tows, handles, brakes well. Yes, it has a PacBrake and optional from factory 265/75-16E tires at 3,415#. It is tough to get rid of a TV that tows so well. I don't encourage others to do it, if you look back I do encourage others to tow within ratings.
I will say that I seldom encourage moving from a 2500 to a 3500 SRW, basically the same truck. I usually encourage to go with a DRW.

I just convinced my DD to buy a 2004 Ram 3500 DRW to tow a four horse with small living quarters. This is the same trailer we towed home empty 250 mile with dads 2500, it still had a 2,600# pin empty.
We are currently looking at 2003 to 2007 Ram DRW to get away from our GVWR issue.

[srvnt]

Just some info. Triangle is building a complete line-up of ST tires in a NC plant. Here is a link. Lots of info in each tab.

http://triangletireus.com/truck-tires/tr653/

Didn't see where they manufacture that tire. The specs seem pretty weak too.

[SummitPond]

Didn't see where they manufacture that tire. ...

Triangle Group is a Chinese tire company that manufactures a range of tires for vehicles from passenger cars to construction equipment and tires fit for special purposes. [Wikipedia]

[JRTJH]

Check this "news flash" about Triangle Tire. Dec 17, 2017 (barely 10 months ago) they announced that they are building a "US plant". I can't tell you whether they have the plant "up and running and building ST tires at the facility yet or not"......

http://triangletireus.com/triangle-tire-to-build-plant-in-north-carolina/

My guess would be that current, "in store" ST tires are probably not "built in the new NC facility"...... (but I can't say they aren't, so check the "plant code" on each tire for the actual location)

[Snoking]

Your belief (I think it is you) that because you buy a tire with a higher speed rating LT tire (106 mph?) and then drive slower gives you MORE weight rating is just.....questionable at best. Please show the specs.

Heat kills tires! In the follow quote it is noted that a high speed rated tire can handle extra heat.

"The speed rating tells you the speed the tire can safely maintain over time. A higher speed rating usually means you will have better control and handling at higher speeds — and that the tire can take the extra heat. As a general rule, tires with higher speed ratings also handle better at slower speeds."

People posting heat numberd from maypops in the SW heat were always 20-30 higher than what my Ribs and R250s ran at.

Going back to the origin of ST tires, they got their higher speed ratings based on the 65 MPH speed restriction. Carlisle blew past the restriction to satisfy the bass boat crowd, and others have followed. There is magic in play here somewhere. You get a higher speed rating based on a speed restriction and then up the speed rating and do not lower the weight rating. ST tires have their own lesser testing standards!

The truth in the whole matter is people have been experiencing failures of ST tires for years. Hopefully there are now tire manufactures working to produce better trailer tires. I have long said that the All Season like tread on most ST tires was part of the issue, as they have to much grip on the payment in tight turns, thus rip themselves apart.

A few years ago at the Circus Circus RV in LV I took these two pictures of a semi trailer parked in the site next to me and of my R250s on our 5th wheel at the time. Tread is very similar with no breaks in the outer ribs. Nothing to bit into the payment in tight turns. Chris

[Javi]

Ya'll are aware, that just because a tire; or anything else for that matter, is manufactured in the U.S.A. is not a guarantee that the quality is any better than one made anywhere else in the world.

I design and manufacture a variety of things and I can assure you that the quality of the product is not related to WHERE the plant is... but rather WHO controls the process..

[Snoking]

Ya'll are aware, that just because a tire; or anything else for that matter, is manufactured in the U.S.A. is not a guarantee that the quality is any better than one made anywhere else in the world.

I design and manufacturer a variety of things and I can assure you that the quality of the product is not related to WHERE the plant is... but rather WHO controls the process..

The china made Sailun tires are an example of that, they meet ISO testing standards. Problem is not everyone one is willing to pay for a higher quality product. Bean counters at trailer manufacturers are a prim example. I talked with the owner of NuWa about tires and why he did now use XPS Ribs on their smaller trailers vs the Uniroyal Laredo's they put on them. His answer was his bean counters! This conversion occurred after he picked up my post on Understanding Tire Types and reposted it on the NuWa forum. Chris

[captcolour]

Ya'll are aware, that just because a tire; or anything else for that matter, is manufactured in the U.S.A. is not a guarantee that the quality is any better than one made anywhere else in the world.

I design and manufacturer a variety of things and I can assure you that the quality of the product is not related to WHERE the plant is... but rather WHO controls the process..


Keystones are made in the US which proves the point :rofl:
(sorry, couldn't resist)

[Javi]

Keystones are made in the US which proves the point :rofl:
(sorry, couldn't resist)

No need to apologize, that is actually a good example... but not limited to Keystone.. it is a product of many things but primarily a couple of generations which failed on a large scale to instill personal responsibility and pride in one's self...

It is a rare thing today to hire an individual who actually cares whether his/her work is correct.. They've been taught to just do enough to get by and to blame the next guy for their own faults. "yes I made those parts incorrectly, but it was Javi's fault they're bad, because he didn't check them before he assembled them". :D

[Snoking]

Keystones are made in the US which proves the point :rofl:
(sorry, couldn't resist)

And I am setting here in a Bighorn made by one of Keystones sister companies and have no issue with the quality. We bought it in May of 2016 as an early 2017 model. It has been to Arizona and back twice, and we lived in it full time for more than a year. It is now going to be our NW Summer home and the Laredo is are commuter trailer to our park model in Arizona.

I am new to Keystone, however I can tell you that Thor lets Heartland run their own show more or less! The Heartland factory people are very willing to work with owners directly to resolve issues and/or put pressure on dealers, and will allow you to use mobile repair service if you pay the travel.

Chris

[Javi]

Okay... back to tires...

Somewhere back in this or another thread I seem to remember that tires lose an average of 10% of their load capacity per year of use..

Assuming that this is correct and it is true for both LT tires and ST tires regardless of bias ply or radial ply construction.. if this is so...

Then one considers that the passenger LT tires are required to have a safety margin built into their rating... What would that margin be??? 10%, 20% ????

But the ST tire is not limited to a safety margin and can claim the maximum allowance from the get go... so "0" safety margin... ????

Am I following this correctly??

[rhagfo]

Okay... back to tires...

Somewhere back in this or another thread I seem to remember that tires lose an average of 10% of their load capacity per year of use..

Assuming that this is correct and it is true for both LT tires and ST tires regardless of bias ply or radial ply construction.. if this is so...

Then one considers that the passenger LT tires are required to have a safety margin built into their rating... What would that margin be??? 10%, 20% ????

But the ST tire is not limited to a safety margin and can claim the maximum allowance from the get go... so "0" safety margin... ????

Am I following this correctly??

I believe that is for ST tires, not for LT or passenger tires. If that were true LT couldn't be rated for a life of ten years. That and the 12 year old LT's I took off my 5er last year were still doing very well.
If the 10% rule were in effect for the LT's and it is assumed it is 10% of the current capaciy, after 12 year the tires would only have 773# of capacity left from 3,042. If it is 10% of the original capacity then by the tenth year the capacity would be zero.

[Snoking]

Okay... back to tires...

Somewhere back in this or another thread I seem to remember that tires lose an average of 10% of their load capacity per year of use..

Assuming that this is correct and it is true for both LT tires and ST tires regardless of bias ply or radial ply construction.. if this is so...

Then one considers that the passenger LT tires are required to have a safety margin built into their rating... What would that margin be??? 10%, 20% ????

But the ST tire is not limited to a safety margin and can claim the maximum allowance from the get go... so "0" safety margin... ????

Am I following this correctly??

I have only heard that 10% loss in relation to ST trailer tires. Ran Michelin OEM tire on wives Buick Rainier for 10 years or so, lot of tread left and should have not been able to hold up the SUV with zero capacity left. The RIBs on out 29' Cardinal would have only had 35 percent capacity left on 3 and 25% of the forth when I removed them and sold them for 200 bucks on CL with around 60% percent tread left after around 44K miles on them.

10 years seems to be the long service recommendation for passenger and LT truck tires. Again ST have been in a category of their own for years.

Here is a write up on testing standards.

forums.goodsamclub.com/index.cfm/fuseaction/thread/tid/23225970/srt/pa/pging/1/page/1.cfm

BTW CWtheMAN is FastEagle in this tread, which is one of the many userid's he uses across the interweb. "Chris" was my original userid on RV.net.

[Javi]

Just a note... http://www.tiresafetygroup.com/tires-expire-in-six-years/

[wiredgeorge]

Any of you guys bikers? Let's talk OIL... dino or synthetic? Or if you ain't a biker, perhaps we could talk religion or politics? TWELVE PAGES (so far) of "more taste/less filling" type "discussion". No ones mind was changed. It has been fairly civil but the horse may be dead...

[Javi]

Any of you guys bikers? Let's talk OIL... dino or synthetic? Or if you ain't a biker, perhaps we could talk religion or politics? TWELVE PAGES (so far) of "more taste/less filling" type "discussion". No ones mind was changed. It has been fairly civil but the horse may be dead...

Was a biker, rode a hardtail... not since it hurt to lay one down at highway speeds.. :D

I'm a mechanical engineer... I could talk oil..

Bottom line... don't read it, if it bores you... :D

[Javi]

I have only heard that 10% loss in relation to ST trailer tires. Ran Michelin OEM tire on wives Buick Rainier for 10 years or so, lot of tread left and should have not been able to hold up the SUV with zero capacity left. The RIBs on out 29' Cardinal would have only had 35 percent capacity left on 3 and 25% of the forth when I removed them and sold them for 200 bucks on CL with around 60% percent tread left after around 44K miles on them.

10 years seems to be the long service recommendation for passenger and LT truck tires. Again ST have been in a category of their own for years.

Here is a write up on testing standards.

forums.goodsamclub.com/index.cfm/fuseaction/thread/tid/23225970/srt/pa/pging/1/page/1.cfm (http://forums.goodsamclub.com/index.cfm/fuseaction/thread/tid/23225970/srt/pa/pging/1/page/1.cfm)

BTW CWtheMAN is FastEagle in this tread, which is one of the many userid's he uses across the interweb. "Chris" was my original userid on RV.net.

So, you're assuming or maybe advocating that LT tires don't degrade at all or at some much reduced rate than do ST tires...

I'd like to see documentation on that and on the much touted "SAFETY MARGIN" built into the LT tire..

It is my consideration that any mandated safety margin would most likely be in fitment, rather than in the tire capacity rating..

Can you show documentation to the contrary?

[JRTJH]

:horse: Ain't dead yet.....

This is in my Ford Owner's Manual:

Age
WARNING
Tires degrade over time depending on many factors such as weather, storage
conditions, and conditions of use (load, speed, inflation pressure) the tires experience throughout their lives. In general, tires should be replaced after six years regardless of tread wear. However, heat caused by hot climates or frequent high loading conditions can accelerate the aging process and may require tires to be replaced more frequently.

You should replace your spare tire when you replace the road tires or after six years due to aging even if it has not been used.

Where did the 10 years come from? Ford says 6 years (and even sooner in Texas, Louisiana, Mississippi, Florida, or other "hot" states)...:popcorn:

[travelin texans]

Lately have seen heavy equipment with an open cel. plastic/foam/rubber type material with no air in them, maybe they'll have them on rvs in the future.

[Snoking]

So, you're assuming or maybe advocating that LT tires don't degrade at all or at some much reduced rate than do ST tires...

I'd like to see documentation on that and on the much touted "SAFETY MARGIN" built into the LT tire..

It is my consideration that any mandated safety margin would most likely be in fitment, rather than in the tire capacity rating..

Can you show documentation to the contrary?

Google is your friend.

How Long Do Tires Last?
The average life of a tire is determined by the conditions a tire is exposed to throughout its life - not measured in calendar years. Temperature changes, sun exposure, storage conditions, usage, and maintenance schedules all contribute to the rate at which a tire ages.

It is impossible to determine a tire’s exact life expectancy, because there is no way to account for the level of influence any one of these factors may have on a tire. However, you can defer to the vehicle and tire manufacturers replacement recommendations:

Vehicle manufacturers recommend tire replacement at 6 years

Tire manufacturers' warranties expire at 6 years

Tire manufacturers recommend replacement at 10 years, regardless of tread depth

https://www.discounttire.com/learn/tire-aging

https://www.michelinman.com/US/en/help/do-I-need-new-tires.html

BRMA members include manufacturers of tires, tire related products, and other rubber and polymer based products in the United Kingdom. The BRMA “strongly recommends” that previously unused tires not be used if they are more than 6 years old and that all tires be replaced 10 years from the date of their manufacture.

https://abcnews.go.com/Blotter/tire-industry-fighting-legislation-aged-tires-off-road/story?id=23686666

Remember I said "10 years seems to be the LONG service recommendation for passenger and LT truck tires."

[Javi]

Google is your friend.

How Long Do Tires Last?
The average life of a tire is determined by the conditions a tire is exposed to throughout its life - not measured in calendar years. Temperature changes, sun exposure, storage conditions, usage, and maintenance schedules all contribute to the rate at which a tire ages.

It is impossible to determine a tire’s exact life expectancy, because there is no way to account for the level of influence any one of these factors may have on a tire. However, you can defer to the vehicle and tire manufacturers replacement recommendations:

Vehicle manufacturers recommend tire replacement at 6 years

Tire manufacturers' warranties expire at 6 years

Tire manufacturers recommend replacement at 10 years, regardless of tread depth

https://www.discounttire.com/learn/tire-aging

https://www.michelinman.com/US/en/help/do-I-need-new-tires.html

BRMA members include manufacturers of tires, tire related products, and other rubber and polymer based products in the United Kingdom. The BRMA “strongly recommends” that previously unused tires not be used if they are more than 6 years old and that all tires be replaced 10 years from the date of their manufacture.

https://abcnews.go.com/Blotter/tire-industry-fighting-legislation-aged-tires-off-road/story?id=23686666

Remember I said "10 years seems to be the LONG service recommendation for passenger and LT truck tires."

Actually, I've read much of that already as well as several papers on testing including but not limited to oven testing..

That still doesn't answer my main question of.....

So, you're assuming or maybe advocating that LT tires don't degrade at all or at some much reduced rate than do ST tires...

I'd like to see documentation on that and on the much touted "SAFETY MARGIN" built into the LT tire..

It is my consideration that any mandated safety margin would most likely be in fitment, rather than in the tire capacity rating..

Can you show documentation to the contrary? :whistling:

[mazboy]

Has anyone noticed that this thread is nearly 10 months old?????

Someone may want to start a new thread regarding tires.

[JRTJH]

Has anyone noticed that this thread is nearly 10 months old?????

Someone may want to start a new thread regarding tires.

Age discrimination???? An "elderly thread is just as welcome as a newborn thread" That said, the vast majority of the posts are continuations of the OP, so with the exception of the blinker fluid detour, it's still relevant and on target.... Why start something new? Continuity with us old farts (no I didn't say constipation) and old threads makes life easier.....

Now, back to our regular scheduled programming......

[travelin texans]

Another couple months of this discussion & some of us will have worn out a set of rv tires, can anyone recommend a good brand??? LOL!

[chuckster57]

Well mine have “aged out”, less than 5,000 miles on them in 6 years. No blowouts, should I chance the same brand?

[sourdough]

Age discrimination???? An "elderly thread is just as welcome as a newborn thread" That said, the vast majority of the posts are continuations of the OP, so with the exception of the blinker fluid detour, it's still relevant and on target.... Why start something new? Continuity with us old farts (no I didn't say constipation) and old threads makes life easier.....

Now, back to our regular scheduled programming......

Whew!! When I read this post on the first pass I thought you had addressed "continence" for old folks......a very "slippery" road to go down:D Now constipation and blinker fluid....seems "normal". :lol:

[Old Mustanger]

Has anyone noticed that this thread is nearly 10 months old?????

Someone may want to start a new thread regarding tires.

We need to keep this thread going until we get the name of that dead horse that's being beaten! :D:hide:

[sourdough]

Google is your friend.

How Long Do Tires Last?
The average life of a tire is determined by the conditions a tire is exposed to throughout its life - not measured in calendar years. Temperature changes, sun exposure, storage conditions, usage, and maintenance schedules all contribute to the rate at which a tire ages.

It is impossible to determine a tire’s exact life expectancy, because there is no way to account for the level of influence any one of these factors may have on a tire. However, you can defer to the vehicle and tire manufacturers replacement recommendations:

Vehicle manufacturers recommend tire replacement at 6 years

Tire manufacturers' warranties expire at 6 years

Tire manufacturers recommend replacement at 10 years, regardless of tread depth

https://www.discounttire.com/learn/tire-aging

https://www.michelinman.com/US/en/help/do-I-need-new-tires.html

BRMA members include manufacturers of tires, tire related products, and other rubber and polymer based products in the United Kingdom. The BRMA “strongly recommends” that previously unused tires not be used if they are more than 6 years old and that all tires be replaced 10 years from the date of their manufacture.

https://abcnews.go.com/Blotter/tire-industry-fighting-legislation-aged-tires-off-road/story?id=23686666

Remember I said "10 years seems to be the LONG service recommendation for passenger and LT truck tires."


Snoking, out of curiousity I'm wondering; what do you have against ST tires across the board; what is your fascination with LT tires; why do you try to goad CW who has tried to provide so much information and insight to this forum; why do you seem to troll CW across forums; what is the detailed validation for your seeming "expertise" on tires? CW has provided that. And here's a thought on your response to one of my posts: having a 106 mph rating on a tire, when driven at a slower speed (65mph?), then raises the tires weight rating (my question). Your response is that heat is a tire killer and reducing the speed then reduces the heat.....maybe. But, what happened to the weight carrying ability of the tire originally questioned? HOW does slowing down then increase a tires built in, certified, "weight carrying ability"? It doesn't. Just curious.

[Badbart56]

Just a question: Why do the ST tires not come with a warranty?

[Javi]

Just a question: Why do the ST tires not come with a warranty?They do.. at least all the ones I've met..

[Snoking]

Just a question: Why do the ST tires not come with a warranty?

https://www.goodyearrvtires.com/pdfs/rv_warranty_610.pdf

[rhagfo]

Snoking, out of curiousity I'm wondering; what do you have against ST tires across the board; what is your fascination with LT tires; why do you try to goad CW who has tried to provide so much information and insight to this forum; why do you seem to troll CW across forums; what is the detailed validation for your seeming "expertise" on tires? CW has provided that. And here's a thought on your response to one of my posts: having a 106 mph rating on a tire, when driven at a slower speed (65mph?), then raises the tires weight rating (my question). Your response is that heat is a tire killer and reducing the speed then reduces the heat.....maybe. But, what happened to the weight carrying ability of the tire originally questioned? HOW does slowing down then increase a tires built in, certified, "weight carrying ability"? It doesn't. Just curious.

Sourdough, you got lost in the post it was I that stated because my LT’s are speed rated for 3,042# at 106 mph with the heat created at that speed, then they can easily carry 3,042# at 70!
I think with Chris and I why you guys stick with ST Maypops, China Bombs , Blow Kong’s.

[Local150]

I recently bought a different 5er and immediately took it to my tire dealer and got 4 new tires. My 1st 5er I had a total of 3 blowouts ,and as you all know they cause some damage. Anyway told him I wanted some very good tires,, he recommended a tire by the name of Trailer King, and proposed we use nitrogen rather than air. He said not a lot of advantage with nitrogen but there was some. All 3 blowouts I had was when air temperature was around 100. The new trailer ki g tires were made in china,, ugh. Has anyone heard of these ? Would like your opinions on the tires and the nitrogen

[JRTJH]

.... The new trailer ki g tires were made in china,, ugh. Has anyone heard of these ? Would like your opinions on the tires and the nitrogen

Check the name on the tires I've been posting for the last year. These are the Trailer King tires that were on my Cougar. No way to inspect them without dismounting them from the rim. The tread is separating from the tire carcass and there's no way to know it until it goes BOOM !!!!!

As for nitrogen, the air you breathe, same as the air in your compressor is 78% nitrogen. Unless you're going to tow at 200 MPH or at 30,000', there's not a lot of "extra protection" by adding the other 22% nitrogen. Some will argue, most don't think it's beneficial. My new flatbed aluminum trailer came with nitrogen filled tires. The valve stems have green caps. Although they are supposed to hold pressure better than "normal air filled tires" in the 6 months I've owned it, I've added "real air" to the tires 4 times. That's both tires, so I don't suspect a slow leak in one tire, although I suppose anything is possible...

Anyway, here's a few photos of those "trailer king tires" your dealer is telling you are so great..... Yeah, Right !!!!!

[Snoking]

I recently bought a different 5er and immediately took it to my tire dealer and got 4 new tires. My 1st 5er I had a total of 3 blowouts ,and as you all know they cause some damage. Anyway told him I wanted some very good tires,, he recommended a tire by the name of Trailer King, and proposed we use nitrogen rather than air. He said not a lot of advantage with nitrogen but there was some. All 3 blowouts I had was when air temperature was around 100. The new trailer ki g tires were made in china,, ugh. Has anyone heard of these ? Would like your opinions on the tires and the nitrogen

You did not provide info on the trailer and tire rating, what tire you had and what size and load range of old and new tires. However if you traded one china bomb ST for another then, you would have been much better off with GY Endurance's, Provider's or Maxxis. Your tire dealer sold you what he had in stock, because you are doing your research after the fact instead of ahead of the purchase. Standard operating procedure for a lot of tire dealers. I can bet he said we do not have problems with these tires. Chris

https://tirereviewsandmore.com/trailer-king-st-radial-reviews/

[Local150]

You are correct on all counts

[Local150]

How many miles and how old were these tires that went bad 4 you

[Local150]

Just curious how old and or how many miles did you have on these until you had a rolling bomb. I appreciate the honesty, but am now feeling somewhat I'll. I usually run about 70,, so when one explodes by the time you get her stopped,, damage damage !

[Snoking]

You are correct on all counts

Take the trailer back to him and ask him to replace them with Goodyear Endurance tires. Chris

[Snoking]

Just curious how old and or how many miles did you have on these until you had a rolling bomb. I appreciate the honesty, but am now feeling somewhat I'll. I usually run about 70,, so when one explodes by the time you get her stopped,, damage damage !

Again providing more info would be helpful or fill out a signature that shows trailer info. Trailer King does make LRF and LRG tires. What size and load range are the new Trailer King tires?

Chris

[Laredo Tugger]

A simple dose of of common sense here.
Yesterday I talked to the owner of a big rig tractor that is sometimes parked where I store my 5er. He does long haul deliveries all over the eastern U.S. He said that on the road he see's a lot of RVs on the roadside with tire problems.
That got my attention and pretty much backs everything written here so far.
Happy trails............
RMc

[SummitPond]

Well mine have “aged out”, less than 5,000 miles on them in 6 years. ...

Chuckster

Either you take a lot of close-in trips or need to get out more often!

[flybouy]

I recently bought a different 5er and immediately took it to my tire dealer and got 4 new tires. My 1st 5er I had a total of 3 blowouts ,and as you all know they cause some damage. Anyway told him I wanted some very good tires,, he recommended a tire by the name of Trailer King, and proposed we use nitrogen rather than air. He said not a lot of advantage with nitrogen but there was some. All 3 blowouts I had was when air temperature was around 100. The new trailer ki g tires were made in china,, ugh. Has anyone heard of these ? Would like your opinions on the tires and the nitrogen

Well looking on the "positive side" of this, at least you have lots of experience changing out blown tires. That skill will most likely be used again.

[JRTJH]

How many miles and how old were these tires that went bad 4 you

If you're asking about the tires I posted photos of, they were less than 3 years old (about 28 months if I remember correctly) and less than 5,000 miles. They were on a 8800 pound Cougar fifth wheel with a GVW of 10,000 pounds and a pin weight ranging from 1700 to 1900 pounds, and carrying less than 7500 pounds every time I towed. That's roughly 1875 pounds on each tire (assuming the trailer is equally loaded on all 4 tire positions) with a 2540 pound load capacity, so definitely not overloaded. And, no, they weren't abused, never towed over 65MPH and always checked for proper pressure before every leg of every tow.

[Javi]

So, what happened... I asked a fair question, especially amid the discussion and proselytizing on LT tires and their miraculous lack of deterioration, built in safety margins concerning load capacities, life expectancies, etc.

I am an engineer, I need more than... I researched it, I believe, I personally ran... etc. I need proof, documentation, results which can be quantified..

I repeat...

So, you're assuming or maybe advocating that LT tires don't degrade at all or at some much reduced rate than do ST tires...

I'd like to see documentation on that and on the much touted "SAFETY MARGIN" built into the LT tire..

It is my consideration that any mandated safety margin would most likely be in fitment, rather than in the tire capacity rating..

Can you show documentation to the contrary? :whistling:

So far I have not seen irrefutable evidence to support the assertion that I break the law/rules or policies in the tire industry by mounting tires which have less load capacity than the O.E.M. fitment...


I'm waiting...

[Snoking]

So, what happened... I asked a fair question, especially amid the discussion and proselytizing on LT tires and their miraculous lack of deterioration, built in safety margins concerning load capacities, life expectancies, etc.

I am an engineer, I need more than... I researched it, I believe, I personally ran... etc. I need proof, documentation, results which can be quantified..

I repeat...

So, you're assuming or maybe advocating that LT tires don't degrade at all or at some much reduced rate than do ST tires...

I'd like to see documentation on that and on the much touted "SAFETY MARGIN" built into the LT tire..

It is my consideration that any mandated safety margin would most likely be in fitment, rather than in the tire capacity rating..

Can you show documentation to the contrary? :whistling:

I can only give you documented facts from my personal experience if you fail to want to do your own research or read what I posted earlier.

In June of 2004 we purchased a new 205 29WBLX Cardinal which came with Kenda Klever LT235/85R16E tires. These china bombs were noted on many forums for early failure. I contacted Kenda and presented a case to remove them before failure, as I was going to retire and travel a lot with the trailer. They gave me 110 dollars each to remove the 5 tires and have them destroyed by the tire dealer. Note: I was given a choice of replacement Kenda ST235/80R16E tires, many that took that route paid a price of failure of those replacements.

I went to a Michelin Commercial tire shop and had LT235/85R16E XPS Ribs installed include the spare. I ran these tires for 6.5 years and around 44K miles, and removed them with around 60 percent tread remaining and sold them on CL for 200 bucks to a guy tickled pink to get them for an old Ford pickup he used for garbage dump runs. I installed Bridgestone Duravis R250s and they where still going strong 4 and a half years later when I sold that trailer.

Both the Ribs and R250 are rated as recapable tire do to their steel ply carcass. There is only one other LT LRE tire that I have routinely endorsed for trailer use in the Bridgestone Duravis R500HD with has a two ply poly carcass. The R500HD is a commercial rated LT. This tire has a rib style tread without breaks in the outer ribs.

https://www.bridgestonetire.com/content/dam/bridgestone/consumer/bst/tires/models/duravis-r500-hd/tilted.jpg/_jcr_content/renditions/cq5dam.web.1280.1280.jpeg

Of the three I think the R250 is the best choice for a 16" LT trailer tire for a 5200 or 6K axle.

[Javi]

I can only give you documented facts from my personal experience if you fail to want to do your own research or read what I posted earlier.

In June of 2004 we purchased a new 205 29WBLX Cardinal which came with Kenda Klever LT235/85R16E tires. These china bombs were noted on many forums for early failure. I contacted Kenda and presented a case to remove them before failure, as I was going to retire and travel a lot with the trailer. They gave me 110 dollars each to remove the 5 tires and have them destroyed by the tire dealer. Note: I was given a choice of replacement Kenda ST235/80R16E tires, many that took that route paid a price of failure of those replacements.

I went to a Michelin Commercial tire shop and had LT235/85R16E XPS Ribs installed include the spare. I ran these tires for 6.5 years and around 44K miles, and removed them with around 60 percent tread remaining and sold them on CL for 200 bucks to a guy tickled pink to get them for an old Ford pickup he used for garbage dump runs. I installed Bridgestone Duravis R250s and they where still going strong 4 and a half years later when I sold that trailer.

Both the Ribs and R250 are rated as recapable tire do to their steel ply carcass. There is only one other LT LRE tire that I have routinely endorsed for trailer use in the Bridgestone Duravis R500HD with has a two ply poly carcass. The R500HD is a commercial rated LT. This tire has a rib style tread without breaks in the outer ribs.

https://www.bridgestonetire.com/content/dam/bridgestone/consumer/bst/tires/models/duravis-r500-hd/tilted.jpg/_jcr_content/renditions/cq5dam.web.1280.1280.jpeg

Of the three I think the R250 is the best choice for a 16" LT trailer tire for a 5200 or 6K axle.


That's fine and also your choice.. and your trailer was fitted with LT tires to start with.. It is understandable that you replaced them with same or better.

However you have continually recommended for fitment of your choice of tire onto trailers which were not O.E.M. fitted with LT tires; regardless of that nagging little rule/law or policy of never mounting tires with less load capacity than O.E.M fitment...

Ya'll want to know why I continue to mount ST tires on my trailer.... it's because that's what came on it... Yes I look for something better than the China Bombs that were fitted... But I'm not going to de-rate my tires in doing so..

I've asked you to provide me with documentation to support the claims of hidden safety margins in load capacities, longevity, etc. in the LT tires but to no avail.. So... Adios :facepalm:

[rhagfo]

So, what happened... I asked a fair question, especially amid the discussion and proselytizing on LT tires and their miraculous lack of deterioration, built in safety margins concerning load capacities, life expectancies, etc.

I am an engineer, I need more than... I researched it, I believe, I personally ran... etc. I need proof, documentation, results which can be quantified..

I repeat...

So, you're assuming or maybe advocating that LT tires don't degrade at all or at some much reduced rate than do ST tires...

I'd like to see documentation on that and on the much touted "SAFETY MARGIN" built into the LT tire..

It is my consideration that any mandated safety margin would most likely be in fitment, rather than in the tire capacity rating..

Can you show documentation to the contrary? :whistling:

So far I have not seen irrefutable evidence to support the assertion that I break the law/rules or policies in the tire industry by mounting tires which have less load capacity than the O.E.M. fitment...


I'm waiting...

I have included sections of this post below.

http://forums.goodsamclub.com/index.cfm/fuseaction/thread/tid/23225970/srt/pa/pging/1/page/1.cfm

The testing for (3) endurance was found to be significantly different between the ST and LT tires.

Both the ST and LT are put through the same initial pressure, time and load profile. The total profile lasts 34 hours of continuous run time starting at 85% of rated load and ending at 100% of rated load. To further stress the tires, a load range E tire (nominal 80 psi rating) is tested at a reduced pressure of 60 psi to induce additional load on the tire during testing. (This is reasonable that testing should be conservative.)

But now the endurance testing diverges significantly.

The ST tire is tested at this pressure, time and load profile at 50 mph. After that, the ST test is over.

The LT tire is tested at this pressure, time and load profile at 75 mph. This is a 50% increase over the ST and will induce significant additional load and heating on the tire during testing. After that, the LT test is not complete. Next a “Low Inflation Pressure Performance” test is performed for the LT tire only. The tire pressure is decreased to 46 psi and the tire is immediately run for an additional 2 hours at 75 mph and 100% of rated load.

Thus, the LT tire endurance test is drastically more intense than the ST endurance test.

The testing for (4) high speed performance.

The difference in high speed performance testing between a ST and LT tire is significant. Both tires are tested through a 90 minute speed/time profile.

The ST tire is tested 88% of rated load while the LT tire is tested at 85% of rated load. Thus, the loading is 3% higher based on rated load and this slight advantage goes to the ST tire.

However, the LT tire is tested at significantly higher velocities when compared to a ST tire (99 vs. 85 mph maximum speed). This is a 16% advantage to the LT tire.

Thus, again the overall test for the LT is more rigorous than the ST test.

[Javi]

I have included sections of this post below.

http://forums.goodsamclub.com/index.cfm/fuseaction/thread/tid/23225970/srt/pa/pging/1/page/1.cfm



Like I said, I read all that some time before this discussion started.. However, it also stands to reason that the ST tire would be tested at lower speeds as the standard MPH rating is lower than the LT tire.. that in itself supports the testing parameters. But it does not imply that within the standard fitment and documented MPH restrictions that the ST tire is somehow weaker or less desirable.

From your posts I believe that your trailer was originally fitted with LT tires and by using them you are doing correctly... Where we differ is that you are implying that because you have them that everyone else should too...

The industry rule/law or policy is to never mount tires with less capacity or size than O.E.M. fitment.. By implying that it is okay to mount tires with a documented load capacity of 500 pounds per tire less, is in my opinion irresponsible..

I am not recommending that you switch to ST tires for your trailers, in fact I support your use of the LT tire of your choice as long as its load capacity is equal to or greater than the O.E.M. fitment..

Give me an LT tire in a 235/85/16 that provides 3500 lbs. or more of documented load capacity at my wheel limit of 80 pounds and I'm all over it.. or for that matter find me a 16" x6 rime with a 6 on 5.5" pattern and I'm all over that too... I just don't want to spend several thousands of dollars to replace axles and equipment to do it.. I'd rather just wait and buy a trailer equipped with 7K axles... :D

[rhagfo]

Like I said, I read all that some time before this discussion started.. However, it also stands to reason that the ST tire would be tested at lower speeds as the standard MPH rating is lower than the LT tire.. that in itself supports the testing parameters. But it does not imply that within the standard fitment and documented MPH restrictions that the ST tire is somehow weaker or less desirable.

From your posts I believe that your trailer was originally fitted with LT tires and by using them you are doing correctly... Where we differ is that you are implying that because you have them that everyone else should too...

The industry rule/law or policy is to never mount tires with less capacity or size than O.E.M. fitment.. By implying that it is okay to mount tires with a documented load capacity of 500 pounds per tire less, is in my opinion irresponsible..

I am not recommending that you switch to ST tires for your trailers, in fact I support your use of the LT tire of your choice as long as its load capacity is equal to or greater than the O.E.M. fitment..

Give me an LT tire in a 235/85/16 that provides 3500 lbs. or more of documented load capacity at my wheel limit of 80 pounds and I'm all over it.. or for that matter find me a 16" x6 rime with a 6 on 5.5" pattern and I'm all over that too... I just don't want to spend several thousands of dollars to replace axles and equipment to do it.. I'd rather just wait and buy a trailer equipped with 7K axles... :D

Javi, did you just blow past this statement.

The LT tire is tested at this pressure, time and load profile at 75 mph. This is a 50% increase over the ST and will induce significant additional load and heating on the tire during testing. After that, the LT test is not complete. Next a “Low Inflation Pressure Performance” test is performed for the LT tire only. The tire pressure is decreased to 46 psi and the tire is immediately run for an additional 2 hours at 75 mph and 100% of rated load.

Thus, the LT tire endurance test is drastically more intense than the ST endurance test.


So you feel that with an ST tire rated at 3,500# you need to replace every two years to avoid failure.
Do you replace the LT tires on your F350 every two years?

Then there is your 5er 2015 Cougar 333MKS

Dry 10,330#
Payload 1,760#
GVWR 12,090#

So LT tires in a 235/85-16E with 3,042# capacity would cover the entire GVWR, even though likely supporting less than 10,000#, more like 9,300# based on your stated pin of 2,800# (that is what I remember).
I know most likely your capacity sticker states tire size of ST 235/80-16E so can't legally go to an LT.

Our 2005 Copper Canyon came with LT 235/85-16Es even though my GVWR is 12,360. Being a 2005 I don't have the yellow sticker, just the VIN weight statement inside a cabinet door near the sink, where it holds up a lot better!
I do have an email from Keystone with the build information that states LT 235/85-16s were installed at the factory.

Just saying.
Russ

[ChuckS]

Well I’ll run my LT 14 ply tires for a few more years. Wrapping up fourth year on them. They are Chinese. I am not going to replace a tire because it may have aged.

And yes... I ride motorcycles and the rear tire on both my gold wing and VTX 1300 are car tires. Called “ the dark side”. They last much longer and with a gold wing the rear tire takes a beating.

[Javi]

Javi, did you just blow past this statement.

The LT tire is tested at this pressure, time and load profile at 75 mph. This is a 50% increase over the ST and will induce significant additional load and heating on the tire during testing. After that, the LT test is not complete. Next a “Low Inflation Pressure Performance” test is performed for the LT tire only. The tire pressure is decreased to 46 psi and the tire is immediately run for an additional 2 hours at 75 mph and 100% of rated load.

Thus, the LT tire endurance test is drastically more intense than the ST endurance test.


So you feel that with an ST tire rated at 3,500# you need to replace every two years to avoid failure.
Do you replace the LT tires on your F350 every two years?

Then there is your 5er 2015 Cougar 333MKS

Dry 10,330#
Payload 1,760#
GVWR 12,090#

So LT tires in a 235/85-16E with 3,042# capacity would cover the entire GVWR, even though likely supporting less than 10,000#, more like 9,300# based on your stated pin of 2,800# (that is what I remember).
I know most likely your capacity sticker states tire size of ST 235/80-16E so can't legally go to an LT.

Our 2005 Copper Canyon came with LT 235/85-16Es even though my GVWR is 12,360. Being a 2005 I don't have the yellow sticker, just the VIN weight statement inside a cabinet door near the sink, where it holds up a lot better!
I do have an email from Keystone with the build information that states LT 235/85-16s were installed at the factory.

Just saying.
Russ

Russ...

Not that it really matters but the stickered GVWR of my trailer is 12,350... :D 2 A/C's

No I didn't blow past any part of the report, I simply maintain that standard testing principles dictate that the LT tire be tested to different limits than the ST tire... Testing the ST to the limits of the LT tire would result in higher failure rates... that is a logical conclusion..

I'm also aware of the assembled limitations of my trailer and that the axle is the weak point as it is rated for 5200 lbs. This however does not change the rule/law or policy of not mounting tires of lesser load capacity than the O.E.M.

I could make a good case for using the 3042 lbs. load limited tires in my case; but as you stated, I'd have to circumnavigate the /rule/law or policy of any legitimate tire store such as Discount Tire in order to mount the LT tires on my trailer.. It is painfully evident that the O.E.M. fitment was the ST 235/80R-16E

And I replace my ST tires every two years as relatively cheap insurance... Could I go longer? Yes definitely.. but since I can sell the used tires for $30 - $50 dollars each, and buy new ones from DT with no interest for 6 months, plus free balancing on request, I see no reason to push the odds.

My LT tires on my dually don't set for extended periods of time with any where the percentage of load capacity on them... Perhaps if they did I'd adopt the same curriculum for them..

On average my truck tires are replaced at 3 to 4 years as it is also my daily driver and the tread wears out before they age out. But again they aren't sitting with 14K on them 24/7

[Javi]

Understand my disagreement isn't with the use of the LT tire where it is the O.E.M. fitment...

My disagreement is with the misrepresentation of hidden safety margins, undocumented longevities, and degradation rates; implying that somehow these hidden attributes makes the LT tire far superior for trailer fitment over the ST tire.. Which suggests that in our own interest we should circumnavigate the rules and use the LT tire no matter the consequences or we are somehow less than smart..

[rhagfo]

Javi, Interesting that they increase the GVWR 260# for the second AC. The numbers I posted were off of Keystones web site. I guess so not eat into the 1,760# Payload.

[Javi]

Javi, Interesting that they increase the GVWR 260# for the second AC. The numbers I posted were off of Keystones web site. I guess so not eat into the 1,760# Payload.

Most likely... 'cause full tanks would require me to unload everything from the trailer.. :D

[CWtheMan]

Maxxis is still a 3 maybe 4 year tire. They dry rot and fail from time to time. Maxxis share never grew that large because they had to be special ordered in most cases.

Availability if the GY Endurance is pretty much universal across the county. Discount tire had them in stock when I junked my brand new Goodrides and sold them on CL.

We as tire users are not privy to the materials used by any particular manufacturer. Cording sizes, basic compounds, tread material densities or even the amount of recycled tire materials used in our “new” tires are all confidential.

When brand “A” says one of their tires is good for 60K miles and brand “B” has one that looks identical to brand “A” but its manufacturer will only say it’s good for 40K miles, there is something different, but both tires list the same construction materials on their sidewalls. (?).

My prediction is the GY Endurance will have a better track record than the GY Marathon. It’s not because I have any means of knowing it’s going to be better because of it’s construction or materials. GY has had super good timing when introducing the Endurance brand. The are going to provide OEM tires to an industry that is making a dramatic change in tire fitments for RV trailers by providing a minimum of 10% load capacities for all Original Equipment tires. The GY Marathons were used when RV trailer manufacturers made it a habit of requiring the OE tires to carry the entire load of an axle’s GAWR.

Sure, the Endurance has higher speed ratings. You’re a stickler about tire testing. You may be shocked when you read the requirements ST tire manufacturer’s used to boost the speed ratings above 65 MPH.

(NOTE: Maxxis ST tires are still at 65 MPH. There is no amount of lobbying they can do to change that short of putting speed letters on the ST tires sidewalls. The government made the China ST manufacturers do that. They cannot do less for that other China.)

[CWtheMan]

Okay... back to tires...

Somewhere back in this or another thread I seem to remember that tires lose an average of 10% of their load capacity per year of use..

That 10% is from a Carlisle Tire pdf. It was written about 15 years ago. Lots of industry changes since then. But, the term most used now is fatigue.

Assuming that this is correct and it is true for both LT tires and ST tires regardless of bias ply or radial ply construction.. if this is so...

Then one considers that the passenger LT tires are required to have a safety margin built into their rating... What would that margin be??? 10%, 20% ????
Just about all tire manufacturers, any design, mention that their tire testing exceeds the NHTSA requirements. By how much is immaterial.

But the ST tire is not limited to a safety margin and can claim the maximum allowance from the get go... so "0" safety margin... ????

Am I following this correctly??

You may be confused by the fitment standards as described in FMVSS. Because the LT tires is designed exclusively for light trucks and multi passenger vehicles. When fitted to those vehicles, they are required to provide a percentage of load capacity reserves via recommended inflation pressures. Light truck manufacturers will most times fit tires to the truck's GAWR factors. Those factors will be above the vehicle GVWR, thus the tires cannot be overloaded without the axles being overloaded.

[CWtheMan]

I have only heard that 10% loss in relation to ST trailer tires. Ran Michelin OEM tire on wives Buick Rainier for 10 years or so, lot of tread left and should have not been able to hold up the SUV with zero capacity left. The RIBs on out 29' Cardinal would have only had 35 percent capacity left on 3 and 25% of the forth when I removed them and sold them for 200 bucks on CL with around 60% percent tread left after around 44K miles on them.

10 years seems to be the long service recommendation for passenger and LT truck tires. Again ST have been in a category of their own for years.

Here is a write up on testing standards.

forums.goodsamclub.com/index.cfm/fuseaction/thread/tid/23225970/srt/pa/pging/1/page/1.cfm

BTW CWtheMAN is FastEagle in this tread, which is one of the many userid's he uses across the interweb. "Chris" was my original userid on RV.net.

When I joined this forum I was playing a lot of internet cribbage. CWtheMan is still well known in that venue.

While in the Navy I spent two tours with Fighter Squadron 41. Three years with F4 Phantom II aircraft and three years F14 Tomcat aircraft. While with the F14s I worked an entire cruise on the flight deck as their flight deck maintenance coordinator. My call sign for all those on the flight deck network was FastEagle.

[Javi]

You may be confused by the fitment standards as described in FMVSS. Because the LT tires is designed exclusively for light trucks and multi passenger vehicles. When fitted to those vehicles, they are required to provide a percentage of load capacity reserves via recommended inflation pressures. Light truck manufacturers will most times fit tires to the truck's GAWR factors. Those factors will be above the vehicle GVWR, thus the tires cannot be overloaded without the axles being overloaded.

Actually I was paraphrasing your buddy... I'm not confused.

I was asking him for clarification on his statements concerning the superiority of LT tires for trailer fitment..

[CWtheMan]

Just a note... http://www.tiresafetygroup.com/tires-expire-in-six-years/

No one in the tire industry or even the governing body has a grip on tire aging. Some even ponder the "don't use after 10 year mark".

IMO the best ballpark figures will come from the manufacturer of the tires you're using. Each seem to have different variations.

In my research I found that Carlisle Tire, way back when, were the sort of spokesperson for the ST tire design. Others were soon to follow and the 3-5 year useage became a sort of standard for those tires.

[CWtheMan]

Just a question: Why do the ST tires not come with a warranty?

Example: http://www.towmaxtires.com/content/towmax/docs/2015TBCBWarrantyTowmaxSTRLimitedWarrantyUpdate.pdf

[Javi]

No one in the tire industry or even the governing body has a grip on tire aging. Some even ponder the "don't use after 10 year mark".

IMO the best ballpark figures will come from the manufacturer of the tires you're using. Each seem to have different variations.

In my research I found that Carlisle Tire, way back when, were the sort of spokesperson for the ST tire design. Others were soon to follow and the 3-5 year useage became a sort of standard for those tires.

I understand that.. again, I was rebutting your buddy's claim that LT tires last longer than 10 years when used in RV trailer fitments...

Personally, I'm not going to use my ST tires past 2 years and the LT tires longevity past 3 or 4 years is moot to me for my application, because I wear the tread to minimum before that..

I did enjoy the way he melded the two different test results to provide backup to his contention that LT tires should replace ST tires regardless of rule/law or policy... it was inventive.. :D

[CWtheMan]

So far I have not seen irrefutable evidence to support the assertion that I break the law/rules or policies in the tire industry by mounting tires which have less load capacity than the O.E.M. fitment... [/COLOR]


I'm waiting...

I often write about that subject. Most will not take the time to do a complete research. Out of context info will become overbearing and vary misleading without a complete knowledge of how all the factors, when tired together, cause the entire tire industry to determining the vehicle manufacturer’s selection of the original equipment tires sets the minimum standard for your vehicle, car, truck or trailer.

NHTSA and the tire industry are in complete agreement that the following statement is the standard to be met when selecting replacement tires.

“Replacement tires must be the same size designation as the Original Equipment tires or others recommended by the vehicle manufacturer. They must provide a load capacity equal to or greater than the OE tires provided at the vehicle manufacturer recommended cold inflation pressures.”

This may already be in this thread but I’ll post it again here. It’s a sample of how some of the major tire manufacturers say it.

Goodyear: Never fit tires to a vehicle that have less load carrying capacity than required by the Original Equipment Manufacturer.

Michelin: Never choose a tire that is smaller in size or has less load-carrying capacity than the tire that came with the vehicle.

Cooper: The new tires must have a load carrying capacity equal to or greater than the maximum load carrying capacity specified on the tire placard on the vehicle.

Toyo: Any replacement tire must be of a size and load range that will offer equal or higher load carrying capacity compared to the original equipment (OE) tire on the vehicle.

[CWtheMan]

Give me an LT tire in a 235/85/16 that provides 3500 lbs. or more of documented load capacity at my wheel limit of 80 pounds and I'm all over it.. or for that matter find me a 16" x6 rime with a 6 on 5.5" pattern and I'm all over that too... I just don't want to spend several thousands of dollars to replace axles and equipment to do it.. I'd rather just wait and buy a trailer equipped with 7K axles... :D

In the evolution of tires it has become necessary to better describe the tires in use. Before the internet became saturated with tire information, people in the industry knew what a tire size was without complete instructions. About 5-7 years ago a more formal tire description was introduced. When reading newer information that includes tires size descriptions you will find them identified as "designated size". A tire's designated size is like these two examples. ST225/75R15 or LT235/85R16 are designated sizes. The prefix is part of that size designation thus, it includes a design. Those two designs have their load capacities described by the load range lettering system.

The size designation becomes a factor when complying with the replacement tire selection recommendations to use tires like the OE tires. A well trained tire installer is not going to replace a ST tire with a LT tire, even of the same physical size.

[Badbart56]

Example: http://www.towmaxtires.com/content/towmax/docs/2015TBCBWarrantyTowmaxSTRLimitedWarrantyUpdate.pdf

I should have elaborated. All the tires I buy for my trucks and cars are available with a road hazard warranty. But not ST tires or even LT's if you are installing them on an RV or trailer. I was told this at the Firestone store and at Walmart.

[Snoking]

I use to feel sorry for people forced into ST tires by the overt market of the product. HOWEVER with the effort Goodyear put into the new Endurance and it's record to date, maybe all is not lost. Ever I purchased a set to replace the china bombs that came on the new Laredo.

This does not however make up for all those that suffer damage, loss of use and cost associated with all the ST failures over so many years.

Chris

[CWtheMan]

Our 2005 Copper Canyon came with LT 235/85-16Es even though my GVWR is 12,360. Being a 2005 I don't have the yellow sticker, just the VIN weight statement inside a cabinet door near the sink, where it holds up a lot better!
I do have an email from Keystone with the build information that states LT 235/85-16s were installed at the factory.

Just saying.
Russ


If you're referring to the vehicle certification label, I can assure you there was supposed to be one. The manufacturer’s certification label for trailers must be affixed to a location on the forward half of the left side, such that it is easily readable from outside the vehicle without moving any part of the vehicle.

On our 2003 Everest it was located on the left side forward basement door.


It was a clear violation for Keystone to sell your trailer without the certification label. There is no provision to place it anywhere other than directed by NHTSA.


My research files are quite extensive. More information about vehicle certification and equipment certifications can be found in the following PDF.

I can't get the PDF file to a place to copy. You'll have to put this information in your search engine....REQUIREMENTS FOR MANUFACTURERS OF MOTOR VEHICLES AND MOTOR VEHICLE EQUIPMENT

[cookinwitdiesel]

Just finished reading this entire thread. Lot of good information. I recently got the truck and trailer in my sig both new (2018 GMC 2500HD Denali Diesel and 2018 Hideout 28RKS). Haven't taken it out yet.

For my trailer, it has the following stats:
GVWR: 9660#
Hitch Weight (minimum?): 860#
Max Cargo Payload: 2650#

There are 2x 4400# Axles on it, which is why the hitch must be 860 to satisfy the regulatory stuff (2x4400+860=9660). I have not taken anything onto a scale yet to verify what the actual hitch weight is but I currently have a 1000# WDH on the truck (what Camping World provided with the trailer - think it is a rebranded Curt) and the truck can take up to a 1500# tongue weight (Class V hitch receiver).

The factory installed tires are ST225/75R15 LRD rated at 2540# each @ 65 PSI (which is also what is on the sticker). Combined that gives me 10160# on the tires but only 8800# on the axles. I believe the trailer was around 7000# empty so when I load it up my understanding is I need to keep it closer to the front/hitch and not have any weight added over the axles if I can avoid it. Pretty much once the kitchen is stocked stick to the pass-through storage under the front. Fortunately, I can put a bunch of stuff in the truck bed to help offload the trailer while on the highway. The tires are LoadStar Karrier KR35 which looks like they are made by Kenda and have no speed rating stamped on them. Should I assume they are only rated for 65 mph then? These are definitely "Made in China" tires but based on the vast experience of everyone here, should I start looking for new tires or get a couple years use out of these before starting to worry?

Everything else was background, the bolded stuff is my most pressing concern. Ideally I would have tires rated up to ~80 mph for the trailer - is that realistic/reasonable? In my daily driver (just a Mazda CX-9) I regularly drive up to 10 over the speed limit and never more than 78-79 (got enough speeding tickets as a youth to have gotten that out of my system). I know I wont be going as fast in the truck pulling the trailer but would think that 70-75 is not outside of the realm of possibility especially in good conditions with low traffic.

And I do not know if this would be considered off topic or not...my truck has Goodyear Wrangler SR-A LT265/60R20ES tires installed from the factory. The GMC sticker calls for 60 PSI on the fronts, and 75 PSI on the rears. Goodyear specs the tires at 3195# load @ 80 PSI. My rear GAWR on the truck is 6200#. The front GAWR is 5200#. I have been unable to find an inflation/load chart for these tires - should I be good sticking to the sticker spec'd inflation pressures?

Thanks in advance for the help!

[FlyingAroundRV]

...I can put a bunch of stuff in the truck bed to help offload the trailer while on the highway.


Whoops! Hold on a minute.


Remember that a WDH means weight distribution? That hitch doesn't just re-distribute the weight only one way. It also re-distributes the weight in the back of the truck back onto the trailer too. Have a look at this video. Dave talks about single axle trailers, but weight distribution is weight distribution no matter how many axles you have.
https://www.youtube.com/watch?v=lVg8QgIFJoU

[Snoking]

The factory installed tires are ST225/75R15 LRD rated at 2540# each @ 65 PSI (which is also what is on the sticker). Combined that gives me 10160# on the tires but only 8800# on the axles. I believe the trailer was around 7000# empty so when I load it up my understanding is I need to keep it closer to the front/hitch and not have any weight added over the axles if I can avoid it. Pretty much once the kitchen is stocked stick to the pass-through storage under the front. Fortunately, I can put a bunch of stuff in the truck bed to help offload the trailer while on the highway. The tires are LoadStar Karrier KR35 which looks like they are made by Kenda and have no speed rating stamped on them. Should I assume they are only rated for 65 mph then? These are definitely "Made in China" tires but based on the vast experience of everyone here, should I start looking for new tires or get a couple years use out of these before starting to worry?


Thanks in advance for the help!

This is what I did!

I took our brand new 2019 Laredo 225MK (8K GVWR) to Discount Tire and replaced the Goodride ST225/75R15D's with Goodyear Endurance ST225/75R15E's and never looked back. Our trailer has the same 4400 lb axles. My wheels are rated to 80 PSI and I chose to inflate the LRE tires to 71 PSI.

I sold the 4 OEM tires on CL for 200 bucks in one day.

Chris

[Canonman]

Should I assume they are only rated for 65 mph then? These are definitely "Made in China" tires but based on the vast experience of everyone here, should I start looking for new tires or get a couple years use out of these before starting to worry?

I believe inexpensive tires will have been made inexpensively. They may last a season or even two. Or, they may come apart on your first trip out. The quality control just isn't there for the majority of these cheapo tires. All Keystone is worried about is meeting the minimum federal specs and whether the unit makes it to the dealer's lot. After that it's your problem. Most blowouts are the result of poor inflation, speed and tire age. A good tire will offer a little more forgiveness where a cheap tire may fail more easily and often. If you realize you are on borrowed time with the original tires and monitor the pressures "religiously" keeping the speed down, you might get through a season allowing the checkbook to heal up after such an initial major purchase.
That said, you have made a huge investment in your RV combo. For another few hundred dollars you can protect that investment by installing a set of "quality" tires. You can look on line at the results of having a trailer tire blowout at high speed. It ain't pretty and it sure as heck ain't cheap. Also, invest in a Tire Pressure Monitoring System (TPMS). Well worth the cost in peace of mind and repair expense since you'll be able to know if a tire is in trouble before it blows. Our TPMS saved our vacation and I'd never tow without it.

As for towing speed, I cruise at around 65 mph. If I need to pass, I'm perfectly comfortable bumping up to 75 to safely get around slower traffic.
Just an example of speed vs time on the road, Let's say I limit my cross country driving day to around 8 hours. And, I get about 300 miles per tank of fuel. At this rate I'm stopping at least twice. At 65mph it takes about 4.5 hours to cover the 300 miles. At 75 mph it's 4 hours. 30 minutes difference doesn't mean that much to me. Arriving safely and less stressed does. Let's face it you've got 5 tons of trailer chasing that Duramax. It's a whole different set of driving dynamics compared to driving a passenger car.
Further, I find with the Cougar, I'm using more 2 lane highways than freeways any way. Our motto :When there's a choice, always take the scenic route"!

[cookinwitdiesel]

Thanks for the info, very informative video, I had not considered the weight going back on the trailer at all! Making me completely rethink the use of the WDH system (can just use the hitch without round spring bars obviously). I will have to much more critically look at the trailer next time I hitch it up and go spend a couple hours at some scales assessing all of the different scenarios.

My current to-do list is looking like Goodyear Endurance tires to gain both load and speed ratings (on paper I do not need the additional load but my tires are also of questionable quality) as well as a TPMS system. I figure it makes sense to do them both at the same time since you will have tires off the rims. Any recommendations for TPMS?

I have been reading about Tireminder.

With the new tires, those are the same size, but rated higher load and PSI than my current ones that the sticker on the trailer reflects. Does that mean I would be covered from a legal liability standard and not running my trailer in an "unsafe" condition?

Thanks!

Update: Ordered the tires :) I came up with the 3 following scale weights I should get measured at a CAT scale (since they have the 3 separate pads). Does this make sense to you guys and get me all the needed info to make informed load decisions?

[CWtheMan]

cookinwitdiesel

The tires are LoadStar Karrier KR35 which looks like they are made by Kenda and have no speed rating stamped on them.
################################################## #######
Your tires have a speed rating. Just about every ST tire manufactured in China in the past 2-3 were required to have speed letters. That’s right. The speed lettering system uses alfa lettters to identify different speed restrictions. For instance “J” = 62 MPH –-- “K” = 68 MPH --- “L” = 75 MPH and “M” = 81MPH. There is no speed letter for 65 MPH. ST tires without a speed letter on their sidewalls have a 65 MPH speed limit.

Some ST tire manufacturers mold “Speed Letter” “L” like that on the tire sidewall and it may be followed by the actual speed limit of 75 MPH. The more sophisticated manufacturers will use the a load index number followed by the speed letter that may look like this; 123 L or 123/119 L, the L being the speed letter. Your Keystone owner’s manual has pictures.

[sourdough]

Thanks for the info, very informative video, I had not considered the weight going back on the trailer at all! Making me completely rethink the use of the WDH system (can just use the hitch without round spring bars obviously). I will have to much more critically look at the trailer next time I hitch it up and go spend a couple hours at some scales assessing all of the different scenarios.

My current to-do list is looking like Goodyear Endurance tires to gain both load and speed ratings (on paper I do not need the additional load but my tires are also of questionable quality) as well as a TPMS system. I figure it makes sense to do them both at the same time since you will have tires off the rims. Any recommendations for TPMS?

I have been reading about Tireminder.

With the new tires, those are the same size, but rated higher load and PSI than my current ones that the sticker on the trailer reflects. Does that mean I would be covered from a legal liability standard and not running my trailer in an "unsafe" condition?

Thanks!

Update: Ordered the tires :) I came up with the 3 following scale weights I should get measured at a CAT scale (since they have the 3 separate pads). Does this make sense to you guys and get me all the needed info to make informed load decisions?


Some thoughts: You need to get the WDH with sway and use it. With a huge sail behind your truck weighing almost 10k you will need the sway control. You will also need the WD part. Something not mentioned; the payload of the truck. Should be on the white/yellow sticker inside the driver's door.

Depending on your payload, the part about throwing things in the bed to offset loading them in the trailer may not be possible, although preferable to me and is what I do but my payload is 3190 and I have capacity to do it.

You did the right thing buying the new tires and a load range higher (E). Run them at 80psi. My trailer gvw is 10k and the LRD China bombs self destructed the start of my 2nd season. Your trailer is almost 10k. The LRD tires were not sufficient for that weight IMO. The LRE tires are better but still marginal to me. I figure the full weight of the trailer plus some is on those tires from time to time depending on the terrain, road and orientation of the truck and trailer to each other. I also run my truck LT tires at 80psi when towing.

I use the TST 507 TPMS and have been pleased. Have them put metal valve stems in when you have the new tires mounted.

[cookinwitdiesel]

Thanks for the help guys. Current Karrier KR35s show 113/108M on them.

The Goodyears are getting installed Thursday, and yes, I am having steel stems put in as well. I already got a TireMinder A1A ready to go on the new stems. I was planning to run the Goodyears at 70-75 PSI, didn't think I would need to max them out at 80? Keep in mind, the axles they are attached to max out at a combined 8800#. The Dexstar rims are rated up to 2860# of load. Here is my spreadsheet I made to track everything (all info pulled either from the tires, the manual, or sticker on the vehicle).

As noted, I will be running a relatively low margin on truck payload. Need to hit a scale once loaded for a realistic camp outing to see what the trailer hitch weight actually is. My stuff in the truck is myself and family (about 350#) and then will likely have:

Generator
5 Gallon Gas Can
Spare 20# Propane Tank
Small compliment of tools (wrenches, tire irons, etc)
My "Tech" bag
Backpack for baby stuff (daughter is 14 months old)

I can't imagine that I will possibly have more than 600# of non-human cargo, plus 350# of us coming out to 950# plus hitch plus trailer tongue weight all needing to be under 2200#. I would think I should be ok but down the road a heavier trailer will change the math.

I have to say, comparing the sticker payload for my VIN to the "specs" online - 300# disappeared that I would rather have available!

Was not going to just abandon the WDH, but curious to see how the weights distribute around. I cannot imagine my trailer getting close to the GVWR which means there should be some room on the trailer axles to carry some more load from the WDH.

[sourdough]

You seem to dodge/ignore the payload question so I assume you will be over that number and rely on the gvwr. What about gawr? When someone determines that is the way they want to tow there's not a lot that folks that want to help and keep you out of trouble can do - nor any reason to ask.

[CWtheMan]

Thanks for the help guys. Current Karrier KR35s show 113/108M on them.

The Goodyears are getting installed Thursday, and yes, I am having steel stems put in as well. I already got a TireMinder A1A ready to go on the new stems. I was planning to run the Goodyears at 70-75 PSI, didn't think I would need to max them out at 80? Keep in mind, the axles they are attached to max out at a combined 8800#. The Dexstar rims are rated up to 2860# of load. Here is my spreadsheet I made to track everything (all info pulled either from the tires, the manual, or sticker on the vehicle).

As noted, I will be running a relatively low margin on truck payload. Need to hit a scale once loaded for a realistic camp outing to see what the trailer hitch weight actually is. My stuff in the truck is myself and family (about 350#) and then will likely have:

Generator
5 Gallon Gas Can
Spare 20# Propane Tank
Small compliment of tools (wrenches, tire irons, etc)
My "Tech" bag
Backpack for baby stuff (daughter is 14 months old)

I can't imagine that I will possibly have more than 600# of non-human cargo, plus 350# of us coming out to 950# plus hitch plus trailer tongue weight all needing to be under 2200#. I would think I should be ok but down the road a heavier trailer will change the math.

I have to say, comparing the sticker payload for my VIN to the "specs" online - 300# disappeared that I would rather have available!

Was not going to just abandon the WDH, but curious to see how the weights distribute around. I cannot imagine my trailer getting close to the GVWR which means there should be some room on the trailer axles to carry some more load from the WDH.


As listed in your post, the Karrier KR35s (113/108M) have a 75 MPH speed rating.

Spread sheet correction recommendations;

In accordance with newer 2010 regulations, all propane weight became part of the trailer’s GVW (7010#). The battery weight will not officially be a cause to change the CCC label because it's under 100#. If dealer installed with other options that would bring the total above 100#, it would require the dealer to change the CCC label. (All official CCC info can be found in paragraph S10 of FMVSS 571.120).

Because your Endurance tires are LRE the vehicle manufacturer’s recommended inflation pressures for the Original Equipment tires (LRD) are still valid. The tire size did not change. The new tires just have the ability to produce more load capacity via increased inflation and use the same load inflation charts, so the LRD & LRE both provide identical load capacities at 65 PSI and below.

Just an observation: Your OE tires provided right at 15% in load capacity reserves at 65 PSI. That’s well above the RVIA 10% recommendation and in the ballpark with tire industry recommendations of 12-15% in load capacity reserves. I mention this because it’s nice to see that the RVIA recommendations have been taken seriously by trailer manufacturers.

[cookinwitdiesel]

Thanks for the info on the propane and battery weights, you are much more honed in to that stuff than I am and that is why this thread has been so informative to me :)

And yes, I was pleasantly surprised once I started putting everything together in the spreadsheet when I realized that on paper I have decent tires (didn't realize they had a better than 65 mph speed rating at the time either). The idea of putting something a little more reputable on my rims is still comforting though. Should be able to hopefully sell the KR35s for a decent amount to recover some cost. I am replacing all 5 (including the spare). I should buy a tire cover to keep that spare out of the sun too I guess.

I am no expert on tires. You think running them at 65 PSI (for LRD status) is sufficient and a good idea? My main concern is longevity and safety - I do not want them to run hotter than needed or wear out quicker than is necessary. I have weight capacity to spare which gives me some wiggle room.

[CWtheMan]

I am no expert on tires. You think running them at 65 PSI (for LRD status) is sufficient and a good idea? My main concern is longevity and safety - I do not want them to run hotter than needed or wear out quicker than is necessary. I have weight capacity to spare which gives me some wiggle room.


There are a lot of "old school" posters in here when it comes to ST tires and they are going to say, all ST tires need 100% inflation pressures. Your New tires are also "new school" tires.


The best reason to increase their inflation above the recommended 65 PSI is for their protection. The best recommendation you're going to get will be from an Endurance trailer tire expert.


RV trailers are notorious for having unbalanced load capacities on their axles. Some times a single wheel position will be so misbalanced it will be over loaded at the recommended inflation pressure. Without having a weight slip that includes individual wheel position weights, it's always going to be safe to consider maximum inflation for tire protection against overloads.

[cookinwitdiesel]

So just run them at 80 PSI? I will not be going over 70 very often at all so still have some headroom in speed - which should help keep them in a healthy temperature range I would think. Will the trailer tire PSI make much of a difference in ride quality for us up in the truck?

[flybouy]

So just run them at 80 PSI? I will not be going over 70 very often at all so still have some headroom in speed - which should help keep them in a healthy temperature range I would think. Will the trailer tire PSI make much of a difference in ride quality for us up in the truck?

If ride is the concern I don't think it will be a factor but try it out if you feel lucky. Inflate to one pressure, drive over a section of road, inflate to another pressure and drive over the same road, same direction and speed, and see if there's a big difference. Lucky? I used that term because I'm one of those "old school guys". If your concern for ride is greater than safety then maybe you should buy a class A. Towing is nothing but compromise and I don't for a minute believe a word of the "don't know it's back there crowd" but I'll give them the benefit of doubt and say they must not be very observant.:)
:popcorn:

[JRTJH]

Ain't nobody (that's conscious) tows nothing bigger than a jet ski on a trailer without "knowing it's back there". If they do "forget it's back there" they are the ones that are cutting off traffic as they "fly by and cut back into the right lane"....

Any vehicle that is capable of towing a 5 ton "box" with no physical limits that can be noticed, is not the kind of tow vehicle any of us could or would want to pull, given the "anti-dually" sentiment because of the "extra width"....

If you're in the "I can't tell it's back there" crowd, please buy larger rear view mirrors and put a yellow flashing light on each side of your trailer so you can keep reminding yourself that, "Yes, Dorothy, this is Kansas"..... :hide:

[cookinwitdiesel]

A Class A is not happening due to multiple factors, primary among them is cost (both upfront and ongoing). Driving one is also a completely different game from having something that can bend in the middle :)

I have no illusions about whether I know the trailer is back there or not, IT IS.

And on the anti-dually sentiment - the second wheel does not stick out any further than the trailering mirrors do so that is all fear and feelings vs actual reality in my mind.

But back to tires :) I will try them out at 80 PSI and see how things feel. Thanks again for the help guys!

[CWtheMan]

This subject will normally be hotly debated when it comes-up in tire forum threads. In this presentation I’m going to provide information from numerous references. It’s the only way a reasonable explanation of misapplications can be described. Try to remember, when reading this, that I’m presenting this information from numerous regulating regulations and tire industry standards.

The reference to a tire being misapplied is most commonly found in individual tire manufacturer tire warranty information documents. In that context they just use the word without any explanations. That opens the door to all sorts of speculations. For this presentation the word misapplication means, to use something for the wrong purpose or in the wrong way.

For there to be an official wrong way there has to be a precedent somewhere that describes the wrong way. Sure enough, there is. It’s in an active federal regulation for tire inspections. Here is the verbiage; “A mismatch in size and construction between tires on the same axle, or a major deviation from the size recommended by the vehicle or tire manufacturer, is a cause for rejection.” The prefix in this tire size example, LT235/85R16 is officially part of the tire’s size. Therefore, LT describes a tire designed primarily for Light Truck applications. In this size, ST235/85R16, the ST describes a tire designed for Special Trailer service. One used in place of the other is a major deviation.

There are several ways to work around the misapplication. One is to use tires clearly marked with , “ for trailer service only”, on their sidewalls, to replace ST tires. The most common tire in that category is the Goodyear G614 RST. Another option is to ask the vehicle manufacturer to approve a replacement tire, of your choice, for replacing the OE tires they installed on your trailer. NHTSA approves the use of an axillary tire placard, adjacent to the original placard, when ‘plus sized” tires are approved and installed as replacements. It needs to show the replacement tire size, maximum load capacity and recommended cold inflation pressures. I’d also want a signed endorsement from the vehicle manufacturer supporting their approved use of such replacements.

[flybouy]

...."Another option is to ask the vehicle manufacturer to approve a replacement tire, of your choice, for replacing the OE tires they installed on your trailer. NHTSA approves the use of an axillary tire placard, adjacent to the original placard, when ‘plus sized” tires are approved and installed as replacements. It needs to show the replacement tire size, maximum load capacity and recommended cold inflation pressures. I’d also want a signed endorsement from the vehicle manufacturer supporting their approved use of such replacements."

Good luck with that. Have you EVER heard of this being done? My guess would be IF you received a response it would be a canned statement in legalese.

[CWtheMan]

When I write things like that I’m almost always getting the information from established industry references. So, lets look at some of them.

The following quote is verbatim from the 2019 Keystone generic owner’s manual. It’s a standard answer that is placed in all RV trailer owner’s manuals as mandated by NHTSA. “The” tire dealer they refer to is the one selling that size and brand.

“To maintain tire safety, purchase new tires that are the same size as the vehicle’s original tires or another size recommended by the manufacturer. Look at the Tire and Loading Information label, or the sidewall of the tire you are replacing to find this information. If you have any doubt about the correct size to choose, consult with the tire dealer.”

The following information is about replacement tires and is the tire industry standard, as written in the RV section of the USTMA PDF.

“When tires need to be replaced, do not guess what tire is right for the vehicle. For the answer, refer to the vehicle tire placard, certification label, or in the vehicle owner’s manual for any additional tire replacement recommendations. The vehicle tire placard identifies the size of the tires, including the spare, that were installed on the vehicle as original equipment (OE). The placard also specifies the recommended cold inflation pressures for the tires on all axles and for the spare. If the vehicle does not have a vehicle tire placard or certification label, consult the vehicle owner’s manual, vehicle manufacturer, or tire manufacturer. A tire dealer should also be familiar with these requirements and is an excellent resource.”

All replacement tire fitments have a set of standards to follow. The USTMA establishes replacement tire standards. Each tire manufacturer may say it a little differently, but the result will be the same. Here is how Michelin says it.

For maximum safety, Michelin recommends to only replace your tires with the same size recommended by the vehicle manufacturer.

Some advice; Never choose a tire that is smaller in size or has less load-carrying capacity than the tire that came with the vehicle.

Tires should always be replaced with the same size designation — or approved options — as recommended by the vehicle manufacturer.

The correct tire size designated for your vehicle should always be verified with the information in your vehicle owner’s manual or on the tire information sticker/certification label.

Note: It’s common for me to list Michelin references even though they don’t manufacturer ST tires. I live 10 miles from Michelin of North America.

Note: A tire size designation does not include the tire's load range/service description.

[Local150]

Very interesting

[Snoking]

When I write things like that I’m almost always getting the information from established industry references. So, lets look at some of them.

The following quote is verbatim from the 2019 Keystone generic owner’s manual. It’s a standard answer that is placed in all RV trailer owner’s manuals as mandated by NHTSA. “The” tire dealer they refer to is the one selling that size and brand.

“To maintain tire safety, purchase new tires that are the same size as the vehicle’s original tires or another size recommended by the manufacturer. Look at the Tire and Loading Information label, or the sidewall of the tire you are replacing to find this information. If you have any doubt about the correct size to choose, consult with the tire dealer.”

The following information is about replacement tires and is the tire industry standard, as written in the RV section of the USTMA PDF.

“When tires need to be replaced, do not guess what tire is right for the vehicle. For the answer, refer to the vehicle tire placard, certification label, or in the vehicle owner’s manual for any additional tire replacement recommendations. The vehicle tire placard identifies the size of the tires, including the spare, that were installed on the vehicle as original equipment (OE). The placard also specifies the recommended cold inflation pressures for the tires on all axles and for the spare. If the vehicle does not have a vehicle tire placard or certification label, consult the vehicle owner’s manual, vehicle manufacturer, or tire manufacturer. A tire dealer should also be familiar with these requirements and is an excellent resource.”

All replacement tire fitments have a set of standards to follow. The USTMA establishes replacement tire standards. Each tire manufacturer may say it a little differently, but the result will be the same. Here is how Michelin says it.

For maximum safety, Michelin recommends to only replace your tires with the same size recommended by the vehicle manufacturer.

Some advice; Never choose a tire that is smaller in size or has less load-carrying capacity than the tire that came with the vehicle.

Tires should always be replaced with the same size designation — or approved options — as recommended by the vehicle manufacturer.
The correct tire size designated for your vehicle should always be verified with the information in your vehicle owner’s manual or on the tire information sticker/certification label.

Note: It’s common for me to list Michelin references even though they don’t manufacturer ST tires. I live 10 miles from Michelin of North America.

Note: A tire size designation does not include the tire's load range/service description.

So CAL, when your Everest came with LRD ST 16", did not continue to install the same thing for years, or did you realize the manufacturer sent it out with tires not up to the job. Even when you upgraded to LRE tires did you not continue to experience tire failures? I little background on your personal tire experience might be a debate equalizer.

Over the years I have seen you continue to post the goodness of ST tires for trailers despite many personal failures. During a similar time frame I ran LT XPS Ribs and R250's without a single failure. How do you explain that?

Without Goodyear's newer Endurance ST, I would have most likely looked to the Goodyear Cargo regional service van/truck tire or the Maxxis Bravo for our new bumper pull this summer.

[CWtheMan]

Sorry, unsat response.

[Snoking]

Those are not trailer tires. They are European designed commercial tires for light vehicles. Much of your Keystone warranty may have been voided with their use. I can show you why that action would have been a misapplication but I know from past experiences that would not be fruitful.



Couldn't be any worst than this.

http://www.doityourselfrv.com/wp-content/uploads/2015/10/20150810w_blowout07.jpg

[sourdough]

So CAL, when your Everest came with LRD ST 16", did not continue to install the same thing for years, or did you realize the manufacturer sent it out with tires not up to the job. Even when you upgraded to LRE tires did you not continue to experience tire failures? I little background on your personal tire experience might be a debate equalizer.

Over the years I have seen you continue to post the goodness of ST tires for trailers despite many personal failures. During a similar time frame I ran LT XPS Ribs and R250's without a single failure. How do you explain that?

Without Goodyear's newer Endurance ST, I would have most likely looked to the Goodyear Cargo regional service van/truck tire or the Maxxis Bravo for our new bumper pull this summer.

I'm wondering if your intention is to post information beneficial to members or just troll CW and continuously rap ST tires that most folks use....as the manufacturers recommend??

[Snoking]

I'm wondering if your intention is to post information beneficial to members or just troll CW and continuously rap ST tires that most folks use....as the manufacturers recommend??

If you knew what the manufacturers paid Tredit and Tireco for a RV wheel and chinese ST tire you might change you feeling on the issue. If you see a china bomb ST235/80R16E at retail for 60 or 70 dollars, what do you think a train car load of them cost the trailer manufactures.

Lucky there are slowly becoming some better quality ST available, however it has been a long and bumpy road getting to this point. Cal's record speaks for it's self. He is all over the inter with many different user names promoting ST tires as if his is on the manufacturers payroll.

Enough said. Chris

[notanlines]

Snoking, "Enough said. Chris" If there is a god, and there certainly is, you will be telling the truth.

[CWtheMan]

Tire industry news has reported that Triangle Tires will soon be manufactured at a NC plant. The attached reference depicts their tire line-up.

They have added a ST235/80R16 LRF.

http://triangletireus.com/truck-tires/tr653/

[ctbruce]

If you knew what the manufacturers paid Tredit and Tireco for a RV wheel and chinese ST tire you might change you feeling on the issue. If you see a china bomb ST235/80R16E at retail for 60 or 70 dollars, what do you think a train car load of them cost the trailer manufactures.

Lucky there are slowly becoming some better quality ST available, however it has been a long and bumpy road getting to this point. Cal's record speaks for it's self. He is all over the inter with many different user names promoting ST tires as if his is on the manufacturers payroll.

Enough said. ChrisChris, enough. This isn't the Duramax forum. Here, we all have to play nice and be courteous to each other.

[Tireman9]

Our 2005 Copper Canyon came with LT 235/85-16Es even though my GVWR is 12,360. Being a 2005 I don't have the yellow sticker, just the VIN weight statement inside a cabinet door near the sink, where it holds up a lot better!
I do have an email from Keystone with the build information that states LT 235/85-16s were installed at the factory.

Just saying.
Russ


Russ. If your vehicle did not have the requires Vehicle certification label (GAWR, VIN, Tire Size and inflation plus other information) you need to file a complaint with NHTSA as your RV is not in compliance with DOT regulations and Coper Canyouis required to fix the situation. maybe all they will do is mail you a tticker. I don't know what they will do but theyMUST have the placard on the outside driver side toward the front. That's the law.

[CWtheMan]

For the last couple of weeks I’ve been updating my vast library of tire references. In doing so I’ve determined that in many instances, I’ve been as negligent in writing about tire sizes, as many of the writers of official documents have been.

All of the references that I’ve updated have been more concise with tire descriptions. In the past, tire size was just a couple of words (tire size) put together to inform the reader what a topic might be about. The industry using that short two word phrase was being lackadaisical in their presentation. So was I. Tire size, in itself, does not actually describe a tire’s intended use. Its intended use is only evident when a vehicle manufacturer selects it for use on a specific vehicle. That is done in the vehicle’s final certification process. The governing body document, for RV trailer tires, is the Federal Motor Vehicle Safety Standards (FMVSS). So, here’s a list of designated tire sizes you may find on your trailer’s axles.

ST225/75R15
LT225/75R15
P225/75R15
215/75R17.5

The significance of the prefix in a tire’s designated size is to distinguish its basic design from other designs

The Rubber Manufactures Association (RMA) has recently renamed itself, US Tire manufacturers Association (USTMA). This is a quote from their current document of industry standards;

(“Replacement tires should be the same as the OE size designation, or approved options, as recommended by the vehicle or tire manufacturer. Never choose a replacement tire of a smaller size or with less load-carrying capacity than the OE tire size at the specified vehicle tire placard pressure.”)

You see, they have done it again. At least they set the precedent (size designation) early in the paragraph so they could shorten it later.

[Javi]

For the last couple of weeks I’ve been updating my vast library of tire references. In doing so I’ve determined that in many instances, I’ve been as negligent in writing about tire sizes, as many of the writers of official documents have been.

All of the references that I’ve updated have been more concise with tire descriptions. In the past, tire size was just a couple of words (tire size) put together to inform the reader what a topic might be about. The industry using that short two word phrase was being lackadaisical in their presentation. So was I. Tire size, in itself, does not actually describe a tire’s intended use. Its intended use is only evident when a vehicle manufacturer selects it for use on a specific vehicle. That is done in the vehicle’s final certification process. The governing body document, for RV trailer tires, is the Federal Motor Vehicle Safety Standards (FMVSS). So, here’s a list of designated tire sizes you may find on your trailer’s axles.

ST225/75R15
LT225/75R15
P225/75R15
215/75R17.5

The significance of the prefix in a tire’s designated size is to distinguish its basic design from other designs

The Rubber Manufactures Association (RMA) has recently renamed itself, US Tire manufacturers Association (USTMA). This is a quote from their current document of industry standards;

(“Replacement tires should be the same as the OE size designation, or approved options, as recommended by the vehicle or tire manufacturer. Never choose a replacement tire of a smaller size or with less load-carrying capacity than the OE tire size at the specified vehicle tire placard pressure.”)

You see, they have done it again. At least they set the precedent (size designation) early in the paragraph so they could shorten it later.

So, then.... it would be acceptable to replace an ST235/80R/16 with an LT235/85R/16 because SIZE does matter and the ST vs LT debate is dead... ? ? ?

[CWtheMan]

So, then.... it would be acceptable to replace an ST235/80R/16 with an LT235/85R/16 because SIZE does matter and the ST vs LT debate is dead... ? ? ?

Sorry you got that impression.

The FMVSS describes a LT tire as being designed for Light Trucks. The ST tire is a Special Trailer tire. Therefore, interchangeability would require approval from the vehicle manufacturer as per USTMA standards.

[Snoking]

After years of trailer tire debates, we can all be thankful that there are now much better offerings available.

[Tireman9]

So, then.... it would be acceptable to replace an ST235/80R/16 with an LT235/85R/16 because SIZE does matter and the ST vs LT debate is dead... ? ? ?


I doubt that the debate is dead as long as some want to treat all customers/RV owners as an un-informed mass.


End users are not required to follow the regulations placed on Tire companies or RV assembly plants.


If you care about safety then you do need to follow the general guideline of ensuring that any replacement tire has equal or better specifications for Load and speed capacities. Some folks seem to have a difficulty in understanding the intent behind published standards and fall back on "Do exactly what the words say" nothing less and nothing more and certainly do not think for yourself.


Can you replace an ST235/80R16 with an LT235/85R16? It depends.


What is the load capacity of the ST tire? 2,600# @ 50psi or 3,000# @ 65 or 3420 @ 80 psi ? The example didn't identify the Load Range. Is the ST rated for 65 mph or 75 mph or greater? again incomplete information was provided in the question.



LT235/85R16 in a single application could be rated for 2,623# @ 65psi or 3,042#@80 or 3,415#@95 and the speed ratings could be anything from N ( 87mph) to I suppose H (130mph)


So if the original tire was an ST235/80R16 LR-E Speed L then an LT235/85R16 LR-F Speed N would not be recommended by any competent tire engineer. maybe a tire salesman would as he wants to make the sale.

[CWtheMan]

How it’s supposed to work.

Sure, there are those that set their own standards and are successful with them. You’ll read posts about all sorts of options others use. It’ll be mostly anecdotal in nature.

There isn’t much oversight on how you maintain the tires on anything you use them on, unless, you live in a state with an active vehicle inspection program.

Those of you that often read my posts probably already know I’m a real stickler for regulations and standards. That’s probably coming from my more than 10 years of having the authority to give a pilot a maintenance briefing about the aircraft he/she is going to launch in, from the flight deck of some aircraft carrier. My bottom line – with my signature – to them was, “THIS AIRCRAFT IS SAFE FOR FLIGHT. The aircraft I most often did that with was the F4 Phantom II – The F14 Tomcat – The A7 Corsair - The F/A18 Hornet.

This will be my last post in this thread. It’s going to be more explanatory. Over the years of posting about RV trailer tires I’ve stayed abreast, as best I could, with the changing regulations, standards and trailer manufacturer preferences. They intermingle, a lot, and that makes it confusing to those that have never paid much attention to tire maintenance.

How and why, are the questions most often asked? Where and when questions are close behind.

In the regulations, brands are not going to be mentioned. Tire designated sizes are standardized; brand “A” is statistically equal to brand “B”, on paper. Generally industry standards follow suit. It’s when you read brochures when brands are normally mentioned or when a brand and designated size and model are unique (one of a kind). Right now that distinction falls on the GY ST255/85R16.

OK, here we go. From the top. Federal Motor Vehicle Safety Standards. “These Federal safety standards are regulations written in terms of minimum safety performance requirements for motor vehicles or items of motor vehicle equipment. These requirements are specified in such a manner "that the public is protected against unreasonable risk of crashes occurring as a result of the design, construction, or performance of motor vehicles and is also protected against unreasonable risk of death or injury in the event crashes do occur." Here is a manufacturers guide document; https://www.nhtsa.gov/sites/nhtsa.dot.gov/files/fmvss-quickrefguide-hs811439.pdf

It’s important to always keep in mind that everything in FMVSS is strictly for dissemination and application by vehicle manufacturers. Many readers will pull - out of context - information from individual FMVSS numbers and use them in statements that are only partially correct. That’s often because, like almost all working documents such as FMVSS, the end result will contain links from other sections of the document. For instance, the FMVSS says the minimum tire requirement is for the tires to provide a load capacity equal to the vehicle’s certified GAWR. However, it doesn’t end there. Later in the document, the vehicle manufacturer is directed to use their judgment by determining what they consider an appropriate fitment is for that particular vehicle. It further directs them to then set a recommended cold inflation pressure for those tires that is also appropriate for that vehicle. It goes a step further and requires the vehicle manufacturer to certify that particular fitment for that particular vehicle and put that information on the vehicle federal certification label, in the vehicle owner’s manual and on any affixed tire/load placard. And finally it requires those tire size designations fitted during the build stage to be the same designated size depicted on the vehicle certification label at the time of first sale. Continuing on in this line of information, let’s not forget that those Original Equipment (OE) tires get registered. The listing of their serial numbers is required to be kept on file for five years. (Off topic; owners do a lot of complaining about tire failures but do little to help keep track of such failures. Every time you change tires, register the new ones.).

Just about all of the information I compile and add to my files about tire industry standards come from industry documents that are available on the WWW. Some tire manufacturers are more explanatory than others. Those that do not build Special Trailer (ST) tires will use broad terms that may not be specific enough to give a complete picture for proper tire management. Usually it’s with tire inflation. When I find them disagreeing I go to the US Tire Manufacturers Association USTMA (formally the Rubber Manufacturers Association) for their more defined answers.

The USTMA routinely publishes bulletins. Here are some that are often debated.

https://www.ustires.org/sites/default/files/TISB_44_USTMA.pdf
https://www.ustires.org/sites/default/files/TISB_23_USTMA.pdf
https://www.ustires.org/sites/default/files/TISB_21_USTMA.pdf

Some tire manufacturers have really good documents. Toyo is one of them.
https://www.toyotires.com/media/1489/tiresafety.pdf
https://www.toyotires.com/customer-care/service-bulletins


All tires have the same building processes. Here is a basic chart from Maxxis.

https://www.maxxis.com/technology/how-a-tire-is-made

Remember this; I bring it up in many of my posts. The vehicle manufacturer has the sole responsibility for OE tire selections. For RV trailers they can choose whatever design they deem appropriate. That selection is for that vehicle as it’s certified. Just because you have an older or newer, nearly identical model, with tires of a different basic design (size designation) does not give license to us either on your vehicle.

The vehicle manufacturer can use any highway tire with a DOT logo on it for an appropriate fitment on your trailer. Passenger, Light Truck, Special Trailer or other designated sizes, normally from the low platform of commercial tire markets.

The industry standards for replacement tires are identical for the automotive & RV Trailer industries. However, with years of corporation and collaboration with each other, the tire and automotive industries have developed listings of preapproved replacements for just about all common automotive fitments. Even down to replacing “P” with “LT” or vice versa. Those seeking replacements for their OE RV trailer tire s do not have that luxury. The standard industry and owner manual one liner for RV trailer tire replacements is; seek approval from the vehicle manufacturer. Throughout the industry the replacement tires are required to be of the same designated size as the OE tires or others recommended by the vehicle manufacturer. Never use replacement tires having less load capacity than the OE tires provided.

Like I said earlier, I’m bailing out of this thread with this post. I’ll also be throttling back on my responses to other tire related threads. I don’t use previously written (“canned”) responses and I’m just getting tired of writing the same things over and over again.

I’m also just getting tired of saying right up front “this is the way it’s supposed to be done” and getting responses with “this is the way I do it” and that way is on the other side of the ropes.

[busterbrown]

Like I said earlier, I’m bailing out of this thread with this post. I’ll also be throttling back on my responses to other tire related threads. I don’t use previously written (“canned”) responses and I’m just getting tired of writing the same things over and over again.

I’m also just getting tired of saying right up front “this is the way it’s supposed to be done” and getting responses with “this is the way I do it” and that way is on the other side of the ropes.

I enjoy reading your posts. I hope that you continue to enlighten the RV community with your knowledge base on tire fitments and such.

[sourdough]

I enjoy reading your posts. I hope that you continue to enlighten the RV community with your knowledge base on tire fitments and such.


CW, I want to chime in with Chris. I enjoy your posts. They are informative and helpful. I think we have so many new folks that would benefit from your knowledge. I do however understand writing the same thing again and again can get tiresome. Further, as of late we have had some that want to nitpick everything said about how we are supposed to do things tire related because they don't and want to argue their point which also get tedious. Just remember that the vast majority of the folks on this forum enjoy, appreciate and learn from your posts. And, I will again say that I think it is very important for new owners to get the "real scoop". Do what you feel fits but know your time and effort writing your posts isn't wasted.

[CWtheMan]

The following paragraph is a standard/accepted tire industry quite, for the condition in the quote.

“Speed ratings are the product of laboratory testing – with simulated speeds and loads. To receive any kind of rating, a tire must demonstrate that it’s capable of sustaining a particular speed. Industry standards govern the process of reaching and maintaining a given speed during a test.”

That one is from Bridgestone.

The following reference contains, in part, the reason why we now have speed letters on our ST tires.

https://enforcement.trade.gov/frn/summary/prc/2017-13287-1.pdf

The DOT symbol on the tire sidewall represents an affirmation by its manufacturer that it was tested for whatever speed letter is on the tire sidewall, if any is there. Testing is almost always done by an approved third party. Not ever tire is tested, just whatever is considered sufficient for the speed rating for that Designated Tire Size.

[Tireman9]

The following paragraph is a standard/accepted tire industry quite, for the condition in the quote.

“Speed ratings are the product of laboratory testing – with simulated speeds and loads. To receive any kind of rating, a tire must demonstrate that it’s capable of sustaining a particular speed. Industry standards govern the process of reaching and maintaining a given speed during a test.”

That one is from Bridgestone.

The following reference contains, in part, the reason why we now have speed letters on our ST tires.

https://enforcement.trade.gov/frn/summary/prc/2017-13287-1.pdf

The DOT symbol on the tire sidewall represents an affirmation by its manufacturer that it was tested for whatever speed letter is on the tire sidewall, if any is there. Testing is almost always done by an approved third party. Not ever tire is tested, just whatever is considered sufficient for the speed rating for that Designated Tire Size.




OK. Now all we need to do is find a tire company that makes ST type tires that will put something in writing that there is no time limit on the number of hours their tires can be run continuously at the max rated load & speed.



Looking forward to seeing those links.

[CWtheMan]

OK. Now all we need to do is find a tire company that makes ST type tires that will put something in writing that there is no time limit on the number of hours their tires can be run continuously at the max rated load & speed.



Looking forward to seeing those links.


You're not going to see a link. Not required any more than the specs for the tire cords physical size described on a tire sidewall.


I quoted from a Bridgestone link. Search other manufactures and you'll find the same information written almost word for word.

[Tireman9]

You're not going to see a link. Not required any more than the specs for the tire cords physical size described on a tire sidewall.


I quoted from a Bridgestone link. Search other manufactures and you'll find the same information written almost word for word.




Bridgestone not Michelin make ST tires. Does that tell you something about their opinion of the ST standards as pushed by Goodyear?


Is it your position that ST tires, when properly loaded and inflated should be able to run tens of thousands at highway speed limits till they wear out? If so you should open a store and you would be the most popular tire store in the country for ST tire sales.

[Snoking]

Bridgestone not Michelin make ST tires. Does that tell you something about their opinion of the ST standards as pushed by Goodyear?


Is it your position that ST tires, when properly loaded and inflated should be able to run tens of thousands at highway speed limits till they wear out? If so you should open a store and you would be the most popular tire store in the country for ST tire sales.

That goes back to what I have often said "the origin of ST tires was local service on utility type trailers" and they found their way to Americas freeways on large RV trailers.

[CWtheMan]

Speed ratings, tire testing, what’s the point in pondering them?

The DOT symbol on the tire represents approval. Factual physical findings that would lead to tire failures caused by ineffective testing would surely lead to NHTSA recalls.

A quote from 49 CFR 574.5 Tire identification requirements.

“The DOT symbol constitutes a certification that the marked tire conforms to an applicable Federal Motor Vehicle Safety Standard.”

[CWtheMan]

If the tire testing procedures for Passenger tires differs from the procedures used for testing Light Truck tires but is acceptable because they have different features to perform, than why question the testing procedures for Special Trailer tires? The are just followers.

If the end result of a test is a pass, than what's the beef?

[Tireman9]

If the tire testing procedures for Passenger tires differs from the procedures used for testing Light Truck tires but is acceptable because they have different features to perform, than why question the testing procedures for Special Trailer tires? The are just followers.

If the end result of a test is a pass, than what's the beef?


The "beef" is that the load formula used by US Tire & Rim Association is based on a stated 65 mph operating speed. For someone so enamored with published regulations I don't understand the confusion.
The reason ST tires carry 10 to 20% more load than LT tires of the same dimension at the same inflation is simply because of the stated speed restriction. Otherwise, there is no rational reason for two otherwise identical tires to have different load capacities.


If the difference was based on the tire construction then I would expect to see diferent loads for Polyester tires vs Steel body tires, but those differences simply do not exist.



Anyone can read and blindly follow a regulation but it takes an actual working knowledge of the product to understand the reasoning behind the regulation, to understand the new Science i.e. "Interply Shear" and the tools needed to evaluate the effects (Finite Element Analysis) and point out the problems with simply blindly following the decades old regs.
I bet that today's modern aircraft would not be allowed and maybe not even able to fly if they had to operate under 50-year-old "regulations".:banghead:



http://i63.tinypic.com/dhblp4.jpg

[CWtheMan]

The "beef" is that the load formula used by US Tire & Rim Association is based on a stated 65 mph operating speed. For someone so enamored with published regulations I don't understand the confusion.
The reason ST tires carry 10 to 20% more load than LT tires of the same dimension at the same inflation is simply because of the stated speed restriction. Otherwise, there is no rational reason for two otherwise identical tires to have different load capacities.


If the difference was based on the tire construction then I would expect to see diferent loads for Polyester tires vs Steel body tires, but those differences simply do not exist.






Anyone can read and blindly follow a regulation but it takes an actual working knowledge of the product to understand the reasoning behind the regulation, to understand the new Science i.e. "Interply Shear" and the tools needed to evaluate the effects (Finite Element Analysis) and point out the problems with simply blindly following the decades old regs.
I bet that today's modern aircraft would not be allowed and maybe not even able to fly if they had to operate under 50-year-old "regulations".:banghead:



http://i63.tinypic.com/dhblp4.jpg

So what? It's the approved method. Good luck with taking it to the next rules committee meeting and getting it on the docket.

[ctbruce]

All of this is way beyond the benefit of the forum members and has basically turned into a pi$$ing match between CW and Tireman. I'd like to suggest that if you want to play one upmanship with each other, a better place to do it would be through PMing each other. This is dragging on with no end in sight.

[hankpage]

Since the original post was a statement and not a question I see no reason to continue this thread beyond 213 posts. Everyone has had ample opportunity to give THEIR opinion and interpretation of the subject so I am closing this thread before it gets TOTALLY out of hand. Travel safely, Hank