Tire pressure

[Rweb]

Hey everyone, need a little bit of help. I just put new tires on the trailer that I purchase at Kal Tire. They are 10 ply tires. Now the sticker on the side of our trailer say to keep them at 65 PSI. Kal tire only put them to 60. I phoned over this morning to find out what to put in and they said there rated for 80 psi.... I am so confused. I ran 65 in the old ones, that's what our dealer had told us at the time. Could anyone offer some advice?


Thanks.

On a side note, thanks to everyone on this great forum, I have learned a lot of great tips, ideas, and valuable information.

[SAABDOCTOR]

I WOULD RUN THEM @ 80PSI. That presure will give the the max load. they will run cooler too. did you have them balanced too? if not go back and have it done. Your tires wheel bearing shocks and axles plus everything inside will thank you:D enjoy them.

[chuckster57]

I usually run trailer tires about 5 psi UNDER the molded max on the sidewall.

[Desert185]

Since SAABDOCTOR mentioned balancing...

The owner of the company that manufactured my car hauler told me to not balance trailer tires. Seems like bad advice, but then he's in the business. Opinions?

[CWtheMan]

Hey everyone, need a little bit of help. I just put new tires on the trailer that I purchase at Kal Tire. They are 10 ply tires. Now the sticker on the side of our trailer say to keep them at 65 PSI. Kal tire only put them to 60. I phoned over this morning to find out what to put in and they said there rated for 80 psi.... I am so confused. I ran 65 in the old ones, that's what our dealer had told us at the time. Could anyone offer some advice?


Thanks.

On a side note, thanks to everyone on this great forum, I have learned a lot of great tips, ideas, and valuable information.

The correct air pressure for the replacement tires depends on their design. Replacement tires need to provide - at the minimum - the load capacity the Original Equipment (OE) tires provided at 65 psi. (That's not my standard. That's the tire industry standard. Others may, and often do, dispute it. I do not).

Replacement tires for RV trailers become complicated when they are not the same size and design as the OE tires.

When replacement tires are of the same size but have a higher load range they will provide the same load capacity as the lower load range at the same psi. Here is where it gets complicated. Special Trailer (ST) tire manufacturer's always - maybe a little less than 100% - want that tire design to be operated at full sidewall pressures. Some may agree to a lower air pressure if it's recommended by the vehicle manufacturer. Another tooth puller situation.

Bottom line; Use the air pressure depicted on the ST tire's sidewall as correct when using that design as replacement for the OE tires. Use the air pressure necessary to equal the load capacity of the OE ties when the replacement tires are LT.

Always check wheelwell clearances. Always check the distance between tires - 1" minimum. Make sure the new tires do not exceed the load capacity of the rims. Make sure the replacement tires correctly fit the rim dimensions.

CW

[gearhead]

Sounds like you had 8 ply tires originally, now you have 10 ply. The max air pressure is molded onto the sidewall of the tire. Usually fairly small print. It most likely is 80 PSI cold. Try to find on the back side of the wheel if it is rated for 80 PSI. If the wheel is good for it, I would run max air pressure, 80 PSI.
I can't imagine any mechanical reason to not balance tires on any trailer.

CWtheMan is all over it. Good info.

[Bob Landry]

The armchair engineers usually turn these tire pressure threads into discussions bordering on the rocket science level, but that isn't needed. Some people are constantly adjusting tire pressure to meet some published load/pressure table. I don't. I have gotten and still get the best longevity from running tires on all of my vehicles at the maximum rated pressure stamped on the tire simply because there is less rubber touching the road and they are going to run cooler.. There's no need, IMHO, to fill it with less to compensate for heat and higher pressures because th tire manufacturers have already factored that into the design. it works for me, YMMV.

[W.E.BGood]

Desert185 said, "The owner of the company that manufactured my car hauler told me to not balance trailer tires. Seems like bad advice, but then he's in the business. Opinions?"

The guy who owns the company that built my house told me not to change the filter in my furnace...now there's an "expert's" opinion if I ever heard one. :iws: .

Per my friendly local/been-in-successful-business-for-many-years chief tech, they recommend balancing any wheel operated at highway speeds, particularly if any weight point is over 1/2 ounce...like my TST507 sensors with brass high-pressure stems.

[TomHaycraft]

Since SAABDOCTOR mentioned balancing...

The owner of the company that manufactured my car hauler told me to not balance trailer tires. Seems like bad advice, but then he's in the business. Opinions?

This gets debated from time to time. For those who have been dogmatic about not balancing trailer tires, I have asked the question about how the physics of trailer tires are different than your TV tires. No one has been able to give me an answer. There has been isolated talk about centering the wheel on the balancer, that trailer wheels are not built centered on the center hole, but rather the studs? I can't quite wrap my head around that.

Regardless, we balance the wheels/tires on our TV because if we don't, we'd feel the vibration and be worried about integrity of the tires and suspension. Back to my question about physics. Same action is going on with the trailer tires, we just don't feel it going down the road.

Next question ... how much might an unbalanced trailer tire, lead to the self-destruction and blow outs so commonly discussed on these boards?

[Desert185]

I agree. Trailer tires should be balanced, but I didn't argue the point with him. Sometimes it just isn't worth the effort. :banghead:

[CWtheMan]

The current Keystone Owner’s Manual does not address tire balancing. This is a quote from the owner’s manual, “Keystone RV does not administer the warranty for tires.” And it then gives all the phone numbers for their OEM tire suppliers.

So I checked out two of the references. The TowMax trailer tire warranty does not mention tire balancing. On the other hand, the Uniroyal Laredo - used as OEM by Keystone in the past - does mention balancing.

Those are two completely different designed tires and the LT has to perform well on steer and drive axles.

CW

[Rweb]

Thanks everyone for the replies. I will put 80 PSI in the tires.

I did check the sidewall of the tire, and it does also show 80 PSI. I attached the picture as well.

http://www.keystoneforums.com/attachments/photobucket/img_137986_0_51e68c2cb844cae63154f13ada53dff2.jpg

[gearhead]

I have worked with rotating equipment for 35+ years. Very expensive critical compressors, gearboxes, turbines, and pumps. There is none of that equipment that doesn't get balanced, whether it is a 1750RPM ANSI pump, 13,000RPM hydrogen compressor, or a 80,000HP GE steam turbine. Anyone that recommends to not balance trailers tires for $10 each would lose my business.

[Rweb]

Great information from everyone thanks. So How often should a person get the tires balanced and should they be rotated as well?

[CWtheMan]

The best illustration I can find for the new dot tire balancing technology is in the reference below. We have Bridgestone tires on our SUV and they have the dots in the correct positions.

I’ve seen new ST tires from various manufacturers with the dots on them but cannot find anything that describes their use from their manufacturers. Maybe some of you have them and have some answers.

http://www.bridgestonetrucktires.com/publications/ra_v13_i1/PDF/ra_v13i1%20ask%20doc.pdf.

CW

[gearhead]

My new Maxxis tires (bought and installed yesterday) have a red dot and a green circle. The folks at Discount Tire said the red dot is supposed to be mounted at the valve stem. The green circle is something that is read on the conveyor belt at the factory.

[LarryL]

Just put new set of tires on,tire dealer only put 70psi not 80psi in i will be on the road tomorrow morning early.
want to air tires to 80psi,it is 95 degrees out is ok to air tires up to 80psi,or should I just put 75psi in?
I was camping and had them do two tires at a time,didn't check pressure
until al tires were back on trailer.

[chuckster57]

Tire pressures are best checked "cold" meaning not driven on. If you took them to the tire dealer OFF the trailer, and then put them back on the trailer your fine to add air now.

[CWtheMan]

The subject of tire pressure always seems to be a controversial subject with many opinions.

There is a single source for the correct air pressure to be put into your tires. That’s the vehicle manufacturer. That’s right, the vehicle manufacturer. They built the trailer and by federal regulations they are directed to set the correct air pressure for the Original Equipment (OE) tires and put that information in the vehicle owner’s manual and on the federal certification label/tire placard.

Tire manufacturers provide load inflation charts to assist vehicle manufacturers with tire selection and load inflation. They often recommend increasing tire pressures beyond the vehicle manufacturers’ recommendations for load conditions but they never recommend tire pressures below a vehicle manufacturers recommendations.

The vehicle manufacturers’ recommended tire pressures are the minimum standard for all subsequent tire replacements, even plus sizing with like designs or other designs. The amount of air pressure recommend for the OE tires equates to the amount of load capacity the tire will provide with that air pressure. That load capacity is what the vehicle manufacturer has set as a minimum safety factor for the OE tires. The tire industry will not knowingly recommend replacement tires unable to provide that minimum load capacity.

Here is a current generic reference (4/2014) for Keystone trailers. Tire info starts on page 18.

http://www.keystonerv.com/media/894590/krv_owner_s_manual_-_2015_-_3-19_-_1545.pdf

Here are a few references that support the statement about minimum load capacity.

http://www.tirerack.com/images/pdf/warranty/GY0513.pdf

http://us.coopertire.com/Tire-Safety/Replacement-Tire-Guide/Load-Capacity.aspx

http://www.maxxis.com/sponsorship/automotive/automotive-tire-safety

CW

[Festus2]

CW

While Keystone is federally regulated to set the pressure on OE tires and that pressure may be found in the manual or on labels and stickers attached to the RV, once the owner removes the OE tires and replaces them with something different, then Keystone is out of the picture. I can't see anyone checking with Keystone when setting tire pressure.

When I replaced ours with Maxxis, I referred to their data and recommendations as well as the wheel manufacturer not Keystone.

[CWtheMan]

CW

While Keystone is federally regulated to set the pressure on OE tires and that pressure may be found in the manual or on labels and stickers attached to the RV, once the owner removes the OE tires and replaces them with something different, then Keystone is out of the picture. I can't see anyone checking with Keystone when setting tire pressure.

When I replaced ours with Maxxis, I referred to their data and recommendations as well as the wheel manufacturer not Keystone.

The vehicle manufacturers’ recommended tire pressures are the minimum standard for all subsequent tire replacements, even plus sizing with like designs or other designs. The amount of air pressure recommend for the OE tires equates to the amount of load capacity the tire will provide with that air pressure. That load capacity is what the vehicle manufacturer has set as a minimum safety factor for the OE tires. The tire industry will not knowingly recommend replacement tires unable to provide that minimum load capacity.

That is a snip from my previous post. There are not many references on the WWW to support the industry standard for plus sizing tires. I do have one. I can post it but it requires in-depth reading and selections of the sections/portions of the pdf that fit the circumstances.

CW

On edit: This reference from Toyo may say it best.

http://www.toyotraining.com/toyo_fund_8.php

[CWtheMan]

I probably dig a little deeper into reference materials than most other tire researchers. To the best of my ability my posts about tire regulations and industry standards are factual. In other words, I don’t adlib my posts.

During the 2007 tire rules committee discussions prior to making the most recent changes to the manufacturers regulations (2007), it was determined that the federal certification label must reflect the actual tire size installed on the trailer at the time of first sale. By insuring that particular element of the regulation is consistent insures the buyer and all subsequent owners of the vehicle are aware of the vehicle manufacturers’ original tire selection.

Many first and second owners change tire sizes without regard for tire industry standards and use inferior replacements in size and load capacity. There are always tires that will meet the minimum requirements the trailer builder set with the OE tires. There are many reasons why owners will not play it safe and stay within the industry standards with replacement tires. I could describe many of them but it would just light a fire under those that have strong convictions about their own tire selections.


BA

p.s. When researching such documents as FMVSS 571.120 it will lead you to a chain of other FMVSS topics. Chief among them is vehicle certification. The reader of FMVSS regulations pertaining to RV trailer manufacturers must remember that those regulations were written for the vehicle manufacturer to abide to. Not the end user.

[Festus2]

CW -
I'm not disagreeing with your research or what the "Rules Committee", Federal Certification Labels, FMVSS 571.120 documents, industry standards and other tire "regulations" have mandated. I suspect that almost everyone on here who has switched out their OE tires, all of which are manufactured in China, for either Maxxis or some other more reputable tire, doesn't really care what Keystone has said about doing that. Keystone's tire pressure recommendations are based on the tire that they have put on the rim. Once that tire is removed and replaced with some other tire, usually an upgrade, then Keystone's recommended tire pressure is ignored. Most look at the cold pressure on the new tire and inflate it accordingly. No one looks at the inflation sticker placed there by Keystone any longer.

I would also suspect that most of us have relied on data and other information that comes from the replacement tire manufacturer - whoever that may be. If the manufacturer of the tire says 80 psi then that is what most of us follow.

Most of us are not all that interested in reading what the government "rules and regulations" are about their tires. Perhaps we should be but the reality is that it is neither practical or something that happens in the "real world".

My remarks may be adlibbed and not based on any factual data or backed up by research. I put on Maxxis because they are good tires and inflate them to the pressure that Maxxis recommends. As an "end user" I may not be compliant with all of the various departmental regulations but I do have confidence in both the tires and the pressure that is in them.

[kellydog98]

Simply put...Balanced and @80psi cold in the morning. "bouncey:

[CWtheMan]

Let me back-up a bit here.


“The National Highway Traffic Safety Administration (NHTSA) has a legislative mandate under Title 49 of the United States Code, Chapter 301, Motor Vehicle Safety, to issue Federal Motor Vehicle Safety Standards (FMVSS) and Regulations to which manufacturers of motor vehicle and equipment items must conform and certify compliance.”

The federal government cannot - without a national law - force individuals to conform to the safety standards they require vehicle manufacturers to conform to. Only individual state vehicle inspection laws can enforce such standards. The following statement is from the PA vehicle safety inspection. Are the tires smaller than the manufacturer’s recommended minimum size or below the manufacturer’s recommended load rating?

When backed-up to the wall I’ve always said that individual RV trailer owners are fully responsible for their selection of replacement tires. However, I’ll not back off from safety. Posting how it’s supposed to be done is a challenge.

Here is an abbreviated - by me - scenario of how to apply the vehicle manufacturers’ OE tire information when installing replacements of a different size, design or load capacity.

The first and most important steps are to ensure the trailer has enough wheel well clearance for the plus sized tire and the rims are of the correct size and capable of sustaining the new load capacity and tire pressure. Next is to insure the distance between tires on dual or triple axle trailers are acceptable. Now it’s time to look for tires. The replacement tires need to be able to provide as much load capacity (with air pressure) as the OE tires do/did. Once the desirable tires have been selected, correctly mounted, balanced and installed on the trailer a new recommended tire pressure must be determined. Using a load inflation chart for the replacement tires find the amount of tire pressure needed to equal the load capacity of the OE tires. That is your minimum acceptable tire pressure. After all that is done a notation should be made in the vehicle owner’s manual as to the new tire size and recommended tire pressure. It is also recommended to make up an auxiliary tire placard with the new tire size and recommended tire pressures and place it adjacent to the OE placard.

BA

[Festus2]

Here is an abbreviated - by me - scenario of how to apply the vehicle manufacturers’ OE tire information when installing replacements of a different size, design or load capacity.

Once the desirable tires have been selected, correctly mounted, balanced and installed on the trailer a new recommended tire pressure must be determined. Using a load inflation chart for the replacement tires find the amount of tire pressure needed to equal the load capacity of the OE tires. That is your minimum acceptable tire pressure.

BA

CW -
Your scenario makes good sense in that you have removed all of red tape surrounding certification, regulations, and all of the other compliances out of the equation and what is left seems to be more realistic and practical - something we can and should all strive for.

Having said that, the load inflation chart that you refer to comes from, I assume, the tire manufacturer not from the vehicle manufacturer. And the last step of making a new placard to replace that provided by Keystone? The information on that decal would come from the tire manufacturer, not Keystone would it not?

As you have experienced, the tire topic is always "interesting" and not without controversy. Enough for one day.

[gearhead]

Not to beat a dead horse but:

"The replacement tires need to be able to provide as much load capacity (with air pressure) as the OE tires do/did."

I guess I need to take my Maxxis off and put my Towmax back on. Per both companies websites, the Towmax has 100 pounds more capacity than the Maxxis.
No. I don't think so.

[ocbms]

As most of you have found, Each RV seems to have axles and tires that nearly matches the maximum gross of the RV. That being said I carry the max pressure, 80 psig at about 60 degrees. When the morning temperature is 80 degree, I have over 80 psig. I also use a tire pressure monitoring system, don't drive other 65 mph and slow down if the tire pressure approaches 100 psi.
So Far so good for 3500 Trailer miles.

[Desert185]

I'm attending a gathering with a number of trailers and motorhomes in attendance. Since I've been on this forum I've been more aware of tire brands and air pressures and I am surprised at the number of aging and obviously under inflated tires I see. One trailer looked like one of the tires was down to 25 PSI. I asked a friend about his Maxxis tires on his 5er and he mentioned they were the original tires on the eight year old trailer.

To read some of these tire threads one could become seriously motivated to rid themselves of the "china bombs", buy a TPMS and religiously maintain 80 PSI. Seeing how many don't pay attention to their tires and are obviously complacent due to not having issues could counter that motivation, but I still can't take the chance on my Power Kings. Right now, Maxxis 235/80-16's are in the future before the next big trip. Even at 100# less per tire I'll still have tires capable of the 326's GVW.

[GMcKenzie]

Not wanting to argue tire pressure, but I still think the best way to be sure is to find an nice, open parking lot, make a chalk line across the tread of the tire and drive forward a few feet. Check how the chalk line is wearing off. If the center is wearing off, let some air out, if the outsides are wearing off, add air. It should wear off evenly.

Same goes for the truck tires.

[JRTJH]

Not wanting to argue tire pressure, but I still think the best way to be sure is to find an nice, open parking lot, make a chalk line across the tread of the tire and drive forward a few feet. Check how the chalk line is wearing off. If the center is wearing off, let some air out, if the outsides are wearing off, add air. It should wear off evenly.

Same goes for the truck tires.

Unless there's a significant misalignment issue, I'd guess that less than 10% of RV owners will wear their trailer tires before their "time out" occurs at 5 years from DOM. Even if they are "overinflated" and riding on the center, most owners won't see enough wear to need replacement tires before they "time out".

It might seem like a "feel good" issue to compare chalk marks on the blacktop, but honestly, I'd think that balancing the tires and keeping maximum recommended inflation pressure will reduce heat buildup (tire enemy #1) by reducing sidewall flexing. Since the tires won't "wear out" for almost all of us, trying to keep the tread in even contact with the pavement isn't really that critical. Keeping the tire at maximum pressure seems ( IMHO) to be much more important.

Now, if you can accomplish "even tread wear" and "minimum heat buildup" you're on the right track.

[CWtheMan]

CW -
Your scenario makes good sense in that you have removed all of red tape surrounding certification, regulations, and all of the other compliances out of the equation and what is left seems to be more realistic and practical - something we can and should all strive for.

Having said that, the load inflation chart that you refer to comes from, I assume, the tire manufacturer not from the vehicle manufacturer. And the last step of making a new placard to replace that provided by Keystone? The information on that decal would come from the tire manufacturer, not Keystone would it not?

As you have experienced, the tire topic is always "interesting" and not without controversy. Enough for one day.

Actually tire inflation charts are all approved by the TRA. Tire manufacturers distribute them under their own name brand. In other words, the chart for any Michelin LT235/85R16E or Goodyear of the same size will both have the same chart figures. Likewise for any Goodyear ST225/75R15E or Maxxis of the same size.

Sometimes there is a disparity when a tire of the same size, such as the ST235/80R16E, is manufactured with three distinct load capacities, 3420#, 3500# and 3520#. When reading the certification label for any of those tires you will not find its load capacity there. Without any load capacity description all of those load capacities default to the lowest load capacity. That is one of the primary reason many 7000# axles are derated to GAWRs of around 6750#. I’ll post a picture below.

The auxiliary tire placard is approved to be filled-out by the tire installer and placed adjacent to the Original tire placard. It’s described in the Bridgestone/Firestone plus sizing SOP.

http://www.irv2.com/photopost/showfull.php?photo=22027

CW

[CWtheMan]

Not to beat a dead horse but:

"The replacement tires need to be able to provide as much load capacity (with air pressure) as the OE tires do/did."

I guess I need to take my Maxxis off and put my Towmax back on. Per both companies websites, the Towmax has 100 pounds more capacity than the Maxxis.
No. I don't think so.

Sometimes there is a disparity when a tire of the same size, such as the ST235/80R16E, is manufactured with three distinct load capacities, 3420#, 3500# and 3520#. When reading the certification label for any of those tires you will not find its load capacity there. Without any load capacity description all of those load capacities default to the lowest load capacity.

CW

[CWtheMan]

If you’re using ST tires - and almost every RV trailer with 6000# axles and below have them - you have to stop thinking car/truck tires and start thinking trailer tires. One of the most prolific builders of ST tires says 1/3 of their load capacity can be gone in three years. Why would the tire builder say that? To counter that they also say that ST tires are designed to run all day, every day at full sidewall air pressure. The trailer manufacturers almost always set recommended tire pressures for the ST tire at full sidewall pressures. None of the ST tires have mileage ratings. The are just going to normally age out unless you’re traveling a lot, then your mileage expectations should never exceed 20,000 miles with any of them. Abnormal tread wear is normally caused by something other than the tire manufacturer.

On one hand an owner says their trailer is too heavy for the axles and tires and on the other they are fooling around with tire pressures for tread wear of a smoother ride or because someone else uses such and such air pressure. I recommend getting a load inflation chart for your tires and see what a loss of 5 psi is costing you in load capacity.

Type, tire tread separation, into your computers search engine. There will be lots of references. You may be surprised to find how consistent the answers for the causes are.

BA

[bsmith0404]

Seems like I have read all of this before....maybe 3 or 4 times. Every time someone asks about tire pressures we go through it all over again. Everyone has their own opinions, some have done significant research to educate themselves. I have read more crap on tire pressures, load indexes, etc than I ever thought I would care about. I have checked websites of multiple tire manufacturers to the point of obsession. In the end, I think many of us are saying the same thing, just in a different way.

Tire installers are required by law to install tires that meet or exceed OE specs. The lawyers will get them if they don't and there is an accident that can be attributed to tire failure.

That said, here is what I take away from everything that we as consumers need to worry about. Your tires load capacity MUST meet or exceed the GAWR of your vehicle. Example if your GAWR is 6500 lbs (most likely a 7000 lb axle reduced to match tires) your tires must have a minimum load capacity of 3250. MINIMUM being the key word! Installing tires with greater capacities is not a problem as long as you have clearance and the wheels will support. If you read the tire pressure charts for your tires, they will indicate different load capacities at different pressures. Again, the MINIMUM air pressure required is what will match the capacity of the tire to the GAWR. Using the same numbers as the above example, if your tires require 65 psi to give 3250 lbs of load capacity, then that is the MINIMUM psi required. If your tires have max air pressure rating of 80 psi on the sidewall for a greater max load, nothing stops you from going to the max. Increasing the tire pressure to max (recommended by most manufacturers for ST tires) increases their load carrying capacity and reduces heat and tire fatigue. Bottom line, make sure you are hitting all of the MINIMUMS, but it's okay (and many will agree it's best) to exceed them.

[TomHaycraft]

Tire installers are required by law to install tires that meet or exceed OE specs. The lawyers will get them if they don't and there is an accident that can be attributed to tire failure.

I had to chuckle when reading that and reflecting back on my tire purchase for the trailer earlier this year. I bumped up from the OEM Load Range C to Load Range Ds. Same physical dimensions of the tire. Discount Tire Company, where I purchased and had them mounted (and balanced with TPMS sending units attached!), made it very clear that I was altering the OEM specs for the vehicle. I'm sure a requirement from corporate based on whatever laws, but they made it very clear that I had changed from OEM specs.

The sales person at DTC and I had a good laugh, he knew I was stepping up for a larger margin of safety and thanked me for being patient as he went through what was required of him.

[bsmith0404]

The sales person at DTC and I had a good laugh, he knew I was stepping up for a larger margin of safety and thanked me for being patient as he went through what was required of him.

Gotta love what the lawyers have turned this industry into. I understand if someone is downgrading, but when we have to be warned about the "dangers" of buying a tire that exceeds OE specs it has become ridiculous!

[CWtheMan]

Gotta love what the lawyers have turned this industry into. I understand if someone is downgrading, but when we have to be warned about the "dangers" of buying a tire that exceeds OE specs it has become ridiculous!

OK, here goes - once the mods get bored with my dialog in this thread just say so and I’ll quit.

Tire fitments for RV trailers get super complicated when it becomes time for replacements. RV trailer axles are fitted with Special Trailer (ST) tires 90% (+/-) of the time. Most first time trailer owners are not familiar with the ST tire design.

The replacement tire fitments for our normal everyday motorized vehicles differ tremendously from RV trailer tire fitments. That’s mostly because the tire industry, in collaboration with the automotive industry, develop lists of replacement tire options for our automotive vehicles. You drive into a tire retailer’s business, the tire sales person gets the information about your vehicle and offers you a selection from the list of tires available for your vehicle. Unless you’re going way out in left field there will also be a list of approved plus sized tire selections. That is not going to happen with your trailer tires. There are no lists. The primary recommendation for replacement tires will come from the trailer’s manufacturer. Here is a verbatim paragraph from the Keystone generic owner’s manual dated 4/14.

“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.”

Unless there are tire options in your individual owner’s manual that statement rules, so to speak. That statement help’s a little in explaining Discount Tires’ explanation of going up in load capacity. The logic is that the tire size on the certification label may say something like ST225/75R15D, that is then the official size of the OE tires. To replace them with a ST225/75R15E is a physical change. The most significant part of the change is the ability of the replacement tire to hold 80 psi vice 65 psi for the OE tires.

The bottom line about replacement tires is the tire industry standards. The DOT, via its subordinate divisions have given the sole responsibility of tire selection and fitment to the vehicle manufacturers. The tire industry standards are written to support that decision by the DOT and also to avoid outrageous law suits.

CW

[Festus2]

OK, here goes - once the mods get bored with my dialog in this thread just say so and I’ll quit.

CW

CWtheMan -

The last word belongs to you.

[Desert185]

CWtheMan:

Given your experience, give me a replacement tire recommendation for my signature 5er (235/80-16).

Curious...

[bsmith0404]

CWtheMan:

Given your experience, give me a replacement tire recommendation for my signature 5er (235/80-16).

Curious...

I know I'd go with a 235/85/16F, (my wheels can't take the pressures of a G). Curious to hear what his recommendation is.

[CWtheMan]

CWtheMan:

Given your experience, give me a replacement tire recommendation for my signature 5er (235/80-16).

Curious...

What's wrong with the ones you have on there? According to Keystone specs you probably have 5200# axles. If so you have lots of extra load capacity reserves. The only draw-back is the 65 MPH speed limit.

CW

[CWtheMan]

I know I'd go with a 235/85/16F, (my wheels can't take the pressures of a G). Curious to hear what his recommendation is.

If you're worried about having to change rims you need to verify what their load capacity is. (It's that value that counts). Then see what the physical differences in size between the ST235/80R16E and the ST235/85R16E are. Maybe even asking Keystone what they think about going to the larger ST tire. Lots of ST manufacturers are now building the ST235/85R16E which is rated at 3640# at 80 psi and goes on a 16x6 rim.

CW

[bsmith0404]

If you're worried about having to change rims you need to verify what their load capacity is. (It's that value that counts). Then see what the physical differences in size between the ST235/80R16E and the ST235/85R16E are. Maybe even asking Keystone what they think about going to the larger ST tire. Lots of ST manufacturers are now building the ST235/85R16E which is rated at 3640# at 80 psi and goes on a 16x6 rim.

CW

My rims are rated for 100 psi which is good for the Carlisle 235/85R16F rated for 3960 at 95 psi. Many people are going with a G rated tire, which usually require 110 psi and 6.5" wide rims. I feel the F load range tire gives me plenty of extra load range at more 3000 lbs over the total weight loaded on them (15,840 vs 13,150 fully loaded, 17% difference). IMO, there is no need to change wheels in order to go with a G tire when I can get that kind of breathing room. I have also had very good experiences with the Carlisle Radial Trail RH in the past. Additionally, there is only 1" diameter difference between the 80 and 85 tire so 1/2" on the top side. I have plenty of clearance for these tires. I was just making a point that a person can step up to an F rated tire without changing wheels (in most cases), but to go to a G rated tire usually requires different wheels.

[Desert185]

What's wrong with the ones you have on there? According to Keystone specs you probably have 5200# axles. If so you have lots of extra load capacity reserves. The only draw-back is the 65 MPH speed limit.

CW

I hope they aren't 5200# axles. My 326SRX GVW is 12,600#.

What's wrong with the current tires? I don't have confidence in the Chinese tires.

[bsmith0404]

It's very possible that they are 5200 lb axles. Take that times 2 and you have 10400., subtract your pin weight, probably somewhere around 2500-3000 lbs and the axles are "sufficient " for the weight. Most companies will not spend the money for excessive axle weight ratings.

[JRTJH]

I hope they aren't 5200# axles. My 326SRX GVW is 12,600#.

What's wrong with the current tires? I don't have confidence in the Chinese tires.

There is a "sticker" on the front driver's side of your trailer (just above the tire pressure sticker) that gives the trailer GVWR and GAWR. Check that sticker and you'll know exactly what your axle ratings are.

[Desert185]

5200# axles they are. Didn't think of the pin weight relieving the tires of some of the duty, which is somewhat comforting.

(tx)

[JRTJH]

On my 27RKS, the axles are 5000 lb axles rated at 4400 lbs with a GVW of 10,000. While I'd like to think that the axles are rated to "carry the trailer." the fact remains that in my situation, 1200 lbs of the GVW is intended to be carried by the truck.

Years ago, trailers were "self sufficient" in that the axles were rated at the GVW, but with the "engineering sleight of hand" (magic), now the GVW can be significantly greater than the gross axle capacity. Somewhat "un-nerving" to think about, especially on a "bouncy" road with a full trailer.....

[CWtheMan]

What's wrong with the current tires? I don't have confidence in the Chinese tires.

A lot of people that participate in RV trailer forums feel that way. But, there just isn’t enough official information to support the negative side of all the anecdotal reports we read in tire threads.

IMO once we learn to stay within the normal operating envelope of the ST tire as described by their builders we can expect at least three years trouble free service from them, unless we are high mileage users.

CW

[bsmith0404]

I tend to agree with you. My biggest problem with trailer tires is that the manufacturers put tires on that are already near max capability. Then if our tire pressures get low or road conditions are bad people see premature failures. I personally prefer to have a little breathing room in the tire capacities versus weight they are carrying. My current tires are the original China bombs, but they are nearly two and a half years old so it's time to upgrade

[TDF5G]

I've never had a blowout in 20 years of RVing.

I had two separations exactly one year ago at the same time on my 2009 Cougar 5W, original tires dated July 2008. Took it easy about 50 miles to campground on 3 good tires and the best of the two that were separating, without a blowout. That was a blessing indeed!

I think a tire, any brand will provide proper service if it is used properly by maintaining the maximum recommended pressure,not overloading the tire beyond recommended load rating, and not driving faster than recommended speed rating. Seems to be 65 MPH for all ST tires. I also visually inspect tires during trips at fuel and rest stops and check for excessive heat.

That's my 2 cents.

Thanks