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Old 12-18-2018, 05:51 PM   #81
Tireman9
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IMO Starting with tires that by their initial design intent were allowed to be rated to carry more load than same "size" tires but with the original 65 mph speed limit we end up with ST type tires.

It is the air pressure that supports the load. Else why are there Load Inflation tables in TRA, ETRTO, and JATMA?

The basic form of the Load Formula is Load = Air Pressure x Air Volume with some minor adjustment for type of service (car or truck or trailers that were not allowed to carry passengers) I have never seen or heard of a table that provides Load vs Construction features.

The use of cap ply material is normally the "go-to" when a tire engineer wants to improve the high-speed performance of a tire. I know this is what I did a number of times back in the early '80s when speed ratings became common for the US made tires.

We need to remember that ST tires became speed rated in a response to FTC anti-dumping regulations that "excluded" tires with Speed Ratings. If I, as a tire design engineer had been given the task of developing "new" ST tires that could carry a speed rating (something better than 65 mph) One of the first things I would have tried would be cap ply/strip.

The idea that the RV trailer company would select the smallest (lowest cost?) tire that would meed the MINIMUM DOT requirements is a concept that has been offered a number of times. While there have been a few RV sold with some reserve load I am sorry to observe that they were in the minority.

In an effort to help RV owners I have tried to offer methods and guidance to help owners to select tires that would not just meet the DOT minimums but to many times exceed the DOT requirements.
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Old 12-19-2018, 04:34 AM   #82
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I have chosen the Goodyear Endurance tires as my upgrade for my Premiere 26. Comes with ST205/75-14. Any reason I should/should not go with ST215/75-14? Almost 200# heavier rating and only .5" taller.

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Old 12-19-2018, 05:58 AM   #83
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I am also going to upgrade the tires and wheels on my 2017 Premier 26RBPR in the spring. It's hard for me to believe that a camper with UVW of 6000 lbs. and GVWR of 7500 lbs. (tandem axle setup) came with ST205/75R14 LRC tires on it. I intend to go with ST225/75R15 LRD tires and comparable rims (like the ones that "Gegrad" referenced in another thread). The current rims (5 lug) have a Max. Load of 1900 lbs. stamped on the back. We bought this camper new in September of 2016, really like the floorplan and the camper overall but was very disappointed in the tire size/rims selected for it. This thread (and the currently active thread about buying rims) are good reads and very informative-really appreciate reading what others have to say!
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Old 12-19-2018, 06:24 AM   #84
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Originally Posted by jeff57 View Post
I am also going to upgrade the tires and wheels on my 2017 Premier 26RBPR in the spring. It's hard for me to believe that a camper with UVW of 6000 lbs. and GVWR of 7500 lbs. (tandem axle setup) came with ST205/75R14 LRC tires on it. I intend to go with ST225/75R15 LRD tires and comparable rims (like the ones that "Gegrad" referenced in another thread). The current rims (5 lug) have a Max. Load of 1900 lbs. stamped on the back. We bought this camper new in September of 2016, really like the floorplan and the camper overall but was very disappointed in the tire size/rims selected for it. This thread (and the currently active thread about buying rims) are good reads and very informative-really appreciate reading what others have to say!
You might want to do some research on the axle/spring/wheel/tire issues that member busterbrown faced earlier this year when he broke a spring pack on his "single leaf springs".

Some of the issues he faced were not "tire/wheel" related, but after he upgraded his tires and wheels, the "next weakest link" came into play. While his issues could (probably were) a result of the entire suspension system being "rated at the bare minimum", after upgrading tires/wheels, he wound up with problems deeper under the trailer.

While I'm not suggesting a complete rebuild for you, it might be prudent to take a look (a very close look) at the springs, spring hangars, axle brackets and U-bolts before spending a "ton of money" on new tires/wheels.....

You can get started with his posts here: http://www.keystoneforums.com/forums...ghlight=broken
http://www.keystoneforums.com/forums...ghlight=broken
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Old 12-19-2018, 10:53 AM   #85
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Thanks John, I had not read the entire thread. If I remember right didn't Busterbrown originally break a spring on a trip to Alaska?

I plan to only upgrade my tires. The Goodyears have a higher load rating which should give me the 10% over factor. I never load to max anyway. I plan to keep the 14" rims that came with my TT.

So question still is: Remain with the ST205/75R 14 which is the OEM tire size or move to the ST215/75R 14?

Any reason to/or not to?

The 215 is .5" taller. A bit wider but still rated to mount on my 5.5" wide rim and has a max load rating of 2,200#

the 205 has a max load rating of 2,040
Both at 65 psi

My OEM tires have a load rating of C while the Goodyears are D And I believe my memory tells me the Max load on the OEMs is aprx. 1,800# at 50 psi.

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Old 12-19-2018, 11:11 AM   #86
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Originally Posted by JRTJH View Post
You might want to do some research on the axle/spring/wheel/tire issues that member busterbrown faced earlier this year when he broke a spring pack on his "single leaf springs".

Some of the issues he faced were not "tire/wheel" related, but after he upgraded his tires and wheels, the "next weakest link" came into play. While his issues could (probably were) a result of the entire suspension system being "rated at the bare minimum", after upgrading tires/wheels, he wound up with problems deeper under the trailer.

While I'm not suggesting a complete rebuild for you, it might be prudent to take a look (a very close look) at the springs, spring hangars, axle brackets and U-bolts before spending a "ton of money" on new tires/wheels.....

You can get started with his posts here: http://www.keystoneforums.com/forums...ghlight=broken
http://www.keystoneforums.com/forums...ghlight=broken

Thanks for passing this along John-much appreciated!
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Old 12-19-2018, 01:47 PM   #87
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When changing tire/wheel sizes the obstacles are numerous. The bottom line is; you’re responsible for your actions when you’re not supported by the industry or its regulations.

I’m going to use direct quotes from the industry with this post. I sometimes get a lot of heat when writing unpopular information.

The following quotes are from tire industry standards as published by the US Tire Manufacturers Association (USTMA). The link is provided at the end.

“Before replacing tires, always refer to and follow the vehicle manufacturer’s tire replacement recommendations and restrictions.”

“ALWAYS check the vehicle manufacturer’s recommendations for the OE tire size, load capacity and inflation pressure. It is not always possible to select the same tire size for a replacement tire. NEVER choose a tire of a smaller size or with less load-carrying capacity than the OE tire size at the specified vehicle tire placard pressure.”

“Always use approved tire/rim combinations for rim diameter, width and contour. Refer to tire manufacturer product literature for approved rim specifications.”

“If replacement tires or rims/wheels are of a different size from the OE, be sure that the outside circumference of all tires is within the accepted tolerance of the vehicle manufacturer. Some rims/wheels may not allow correct bead seating unless the OE tire is used. Consult vehicle manufacturer. Never exceed the maximum pressure and/or load capacity of the rim/wheel.”

“Tires specifically designed for travel trailer use in highway service have an “ST” molded on the tire sidewall such as ST225/75R15. Also see Chapter 1 “Basic Tire Information.” ST tires have different load capacity characteristics. Therefore, ST tires should not be replaced with any other type tire.”

https://www.ustires.org/sites/defaul...TruckTires.pdf
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Old 12-19-2018, 04:53 PM   #88
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A good share of what you posted above from the USTMA can also be considered a CYA letter. While it is certainly correct about going down in size it discourages someone thinking of going oversize even by only 1 size. Same way auto manufacturers discourage using different size tires front to rear on a car or truck that is 2 wheel drive. Explain how a rim of OE width might not accept a tire other than OE size. Provided of course that replacement tire was recommended for that width. Again a CYA statement
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Old 12-19-2018, 05:23 PM   #89
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Thanks for passing this along John-much appreciated!
Jeff, since you are upgrading the wheels to 15", you might want to go ahead and just do the tires at LR E, instead of D. Would get extra reserve capacity for the same price. I believe the LR D and E were both like $64 for the Carlisle Radial Trail HDs. I did it and have been completely satisfied.
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Old 12-19-2018, 08:26 PM   #90
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Originally Posted by hornet28 View Post
A good share of what you posted above from the USTMA can also be considered a CYA letter. While it is certainly correct about going down in size it discourages someone thinking of going oversize even by only 1 size. Same way auto manufacturers discourage using different size tires front to rear on a car or truck that is 2 wheel drive. Explain how a rim of OE width might not accept a tire other than OE size. Provided of course that replacement tire was recommended for that width. Again a CYA statement

Load capacity or PSI capacity or both.
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Old 12-20-2018, 05:31 AM   #91
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Jeff, since you are upgrading the wheels to 15", you might want to go ahead and just do the tires at LR E, instead of D. Would get extra reserve capacity for the same price. I believe the LR D and E were both like $64 for the Carlisle Radial Trail HDs. I did it and have been completely satisfied.

Thanks for the good idea, Matt. Since you have the same rims that I am looking at (rated at 2540 lbs) do you run the tire pressure for your LRE's at 80 psi or 65 psi?
It looks like your camper is a bit larger than mine (UVW, GVWR and length), did your camper come stock with 14" LRC or LRD tires?
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Old 12-20-2018, 05:47 AM   #92
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Load capacity or PSI capacity or both.
I was referring to this statement. "Some rims/wheels may not allow correct bead seating unless the OE tire is used. Consult vehicle manufacturer." While the wheel might not be rated for the pressure or load, if the mounting surface is like/similar to the OE wheel then it'll accept the tire and the bead will seat. Also what chance does the average Joe have of getting information from the manufacturer other than printed/parroted CYA statements like you posted?
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Old 12-20-2018, 07:56 AM   #93
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I was referring to this statement. "Some rims/wheels may not allow correct bead seating unless the OE tire is used. Consult vehicle manufacturer." While the wheel might not be rated for the pressure or load, if the mounting surface is like/similar to the OE wheel then it'll accept the tire and the bead will seat. Also what chance does the average Joe have of getting information from the manufacturer other than printed/parroted CYA statements like you posted?
I read both of your statements the same way, where the "some rims/wheels [that] may not allow correct bead seating" are the ones where you will have problems "if the mounting surface is [not] like/similar to the OE wheel". Not sure about trailer tires in general, but for Car/Truck/SUV, different rim contours or bead profiles come to mind. I believe the main thing to watch for bead seating on trailer tires (other than the obvious rim diameters) is the rim widths. If you take a 205 wide tire off of a 5.5" wide rim and try to put on a 225 wide tire, the beads come in at a different angle than they do on a 6" wide rim.

EDIT: I suppose the sidewalls are also not supported correctly by the flanges in that case but that's not directly related to bead seating as much as rim/bead surface contact.

EDIT-EDIT: Do the flanges even support the sidewalls? Maybe not, I am not a tire expert (IANATE?) by any stretch of the imagination.
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Old 12-20-2018, 09:25 AM   #94
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I was referring to this statement. "Some rims/wheels may not allow correct bead seating unless the OE tire is used. Consult vehicle manufacturer." While the wheel might not be rated for the pressure or load, if the mounting surface is like/similar to the OE wheel then it'll accept the tire and the bead will seat. Also what chance does the average Joe have of getting information from the manufacturer other than printed/parroted CYA statements like you posted?

The regulations/standards are written for all possible situations. The automotive industry will, at times, provide wheel/tire assemblies that are unique.


The FMVSS provide minimum standards. The industry must abide. To point out not to do less is not, IMO, a CYA statement by them.
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Old 12-20-2018, 10:28 AM   #95
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I do agree that using an undersize tire/wheel for the load is wrong. However because we have become such a litigious society manufacturers have been forced to use very general CYA statements. It's not just tires, cars, trailers, etc. If it were up to some nothing could be changed in any way shape or form from the way the manufacturer produced it. An example of CYA offerings is. How many times have you bought something and after reading all the warnings asked yourself "How could anyone be so foolish as to use it this way?" Would you use a hair dryer in the shower? Of course not but I'll bet there's a similar warning in the instructions for it.
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Old 12-20-2018, 10:44 AM   #96
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Originally Posted by hornet28 View Post
I do agree that using an undersize tire/wheel for the load is wrong. However because we have become such a litigious society manufacturers have been forced to use very general CYA statements. It's not just tires, cars, trailers, etc. If it were up to some nothing could be changed in any way shape or form from the way the manufacturer produced it. An example of CYA offerings is. How many times have you bought something and after reading all the warnings asked yourself "How could anyone be so foolish as to use it this way?" Would you use a hair dryer in the shower? Of course not but I'll bet there's a similar warning in the instructions for it.
Just another example: Take a gander at a $1 white extension cord. There's two dollars worth of warning labels on it.... My opinon (FWIW) is you can't use the extension cord safely because of all the damn taped stickers that make it impossible to use.
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Old 12-22-2018, 04:31 PM   #97
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Are those replacement tires? If so, were the valve stems replaced? If so, are they the steel bolt-in type? If so, they may not have been torqued properly or the installer may have forgotten to install the inside or outside seals and all there would be is metal to metal sealing.



https://www.bing.com/images/search?q...pixs&FORM=IGRE
Metal valve stems. This morning after sitting for a few weeks 1 tire was down to 63 from 80. Took it to America's tires. They dismounted it, checked everything out and said it could be leaking due to my tst tps sensors on the valves. I'll take them off before i store it next time to see if that makes a difference.
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Old 12-22-2018, 04:44 PM   #98
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Metal valve stems. This morning after sitting for a few weeks 1 tire was down to 63 from 80. Took it to America's tires. They dismounted it, checked everything out and said it could be leaking due to my tst tps sensors on the valves. I'll take them off before i store it next time to see if that makes a difference.

My TST sensors (valve stem) don't leak. I have had multiple problems with sand getting in the schrader valves and then they wouldn't seal. On this trip I had one that would not stop leaking but just screwed the TST sensor on for a stop gap. Hasn't lost a lb in 8 weeks. I would look more closely at the stems, valves etc.
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Old 12-22-2018, 06:23 PM   #99
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Thanks for the good idea, Matt. Since you have the same rims that I am looking at (rated at 2540 lbs) do you run the tire pressure for your LRE's at 80 psi or 65 psi?
It looks like your camper is a bit larger than mine (UVW, GVWR and length), did your camper come stock with 14" LRC or LRD tires?
Jeff,
Mine came with the 14" LR C tires. I joined here a few days after getting home with it (around July 7 2017), started reading about tires, and had my 15" LR E Tires on it by August 20th or so, haha. I ran my tires at 70 psi for the end of 2017, but sometime around May 2018 I figured out how to up the output pressure on my compressor and now I run them at 75 psi.
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Old 02-15-2019, 08:36 PM   #100
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Maybe I'm lucky or maybe I'm pushing my luck, but when every camping season ends I tell myself I'll get rid of my Trailer Kings and put on Endurances at the start of the next season. The Trailer Kings now have 13,700 miles on the and show no signs of wear issues. I just make sure I'm not overloaded and drive at the speed limits with a 65 maximum.
The travel trailer is a 2016 Outback 326RL.
I have a set of Trailer Kings on my 2017 29rkpr with 20k miles on them. So far no abnormal wear nor blemishes. I'll be replacing for this season due to wear only (and they're not particularly worn out at that). I'm just a bit leery with all these discussions I've read.

EDIT: Now I've seen what the inside looks like on some posted here. I'll be changing them out.
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