Tire Information

[Tireman9]

Here is a link to a thread with lots of tire info.

While the thread is in Motorhome the tire info still applies to TT & 5th wheel usage.

[Ray,IN]

There is a caveat here. All ST-Special Trailer- tires must be operated at sidewall maximum. Carlisle states it in their warranty: http://www.carlisletire.com/product_...are_safety.pdf

[FastEagle]

Quote:

Originally Posted by Tireman9 Here is a link to a thread with lots of tire info. While the thread is in Motorhome the tire info still applies to TT & 5th wheel usage.

I don’t see the relevance. Bridgestone and Michelin do not provide Original Equipment tires for the RV trailer industry and Goodyear’s references are notoriously outdated and incorrect.
　
FastEagle

[JIMNLIN]

Goodyear along with Carlisle are probably the oldest ST manufacture out there. Goodyear also recommends max sidewall pressure for tires on a trailer;

Special Considerations

RV TRAILER TIRES

Unless trying to resolve poor ride quality problems with an RV trailer, it is recommended that trailer tires be inflated to the pressure indicated on the sidewall of the tire. Trailer tires experience significant lateral (side-to-side) loads due to vehicle sway from uneven roads or passing vehicles. Using the inflation pressure engraved on the sidewall will provide optimum load carrying capacity and minimize heat build-up.

Bridgestone and Michelin provide excellent replacement tires for a trailer. The XPS Rib and the Duravis R-250 are a all steel fabric tire and are a upgrade option on many top line commercial grade equipment trailers. Some folks think they work fine on a RV trailer also.

[ralper]

Most RV owners replace their tires with like ones. The originals were barely able to do the job to start with. I believe in buying tires rated at least two if not three times more than originals. For example: If your rig came with "D" rated tires replace with "G" rated tires. Made in the USA is a given. My 5er was offered with "E" rated tires. I opted for "G" rated tires. After four years they proved to be too light. I replaced them with "J" rated tires.

[Tireman9]

Quote:

Originally Posted by ralper Most RV owners replace their tires with like ones. The originals were barely able to do the job to start with. I believe in buying tires rated at least two if not three times more than originals. For example: If your rig came with "D" rated tires replace with "G" rated tires. Made in the USA is a given. My 5er was offered with "E" rated tires. I opted for "G" rated tires. After four years they proved to be too light. I replaced them with "J" rated tires.

Ralper. Not sure if I completely understand why you are increasing the Load Range in your tires. Are you really carrying that much extra load?
1. The OE tire size/LR should match the design capabilities of your RV
2. If you feel you needed the increased load capacity offered with increased inflation pressure limits from higher Load Range did you also increase the wheel capacity? Axle & Spring capacity, Frame reinforcement? etc?
3. You didn't provide info on the size tire you are working with. I would be interested to know what tire is available in a D, E, G and J Load range tires
Doing a quick check in T&RA load-Inflation tables and didn't find any ST tires above E or LT above F so are you running some TBR type/size.

Load Range D is generally down in the 65 psi area and J is almost double that at 120 psi, so new wheels are a must.
Wheel failures can be fatal for the tire tech during inflation so are potentially much more catastrophic than just an tread sep and body damage to your TT.

[RustyJC]

Most of us that have upgraded our RV tires do so to improve the margin of safety. It's not at all uncommon for the OEM-supplied tires on larger 5th wheels to be operating at 90% to 95% of their maximum load rating. This, combined with highway speeds and 100+ degreeF ambient temperatures in the Texas summers, has been conducive to expensive tire failures (typically, tread separations) with significant resultant damage to the RVs.

In my case, after two (2) tread separation failures I moved from the OEM Goodyear G614 RST tires (LT235/85R-16G rated 3750 lbs @ 110 PSIG) to the Michelin XTA (215/75R-17.5J rated 4605 lbs @ 125 PSIG) with new 17.5" J-rated aluminum wheels. I made this investment to lessen the possibility of catastrophic tread separation by providing more operating margin between the tire's rated and actual loads, and I'm satisfied to date with my decision.

Rusty

[FastEagle]

As the RV trailer industry ventures deeper into larger and heavier models the tire industry is seeking to provide tires to this market by increasing load capacities in the smallish tires needed for the cumbersome fifth wheel trailers that are going into the 15,000#+ GVWR category with 7000#+ axle ratings. There are a number of tire manufacturers now producing the ST235/85R16 tire in a LRF format that has a load capacity of 3960# at 95 psi. On the LT side you can find the LT235/85R16 tire in a LRG with a load capacity of 3750# at 110 PSI. A number of heavier RV trailer manufacturers are offering commercial truck tires normally in the 215/75R17.5 size range with a LRH rated at 4805# at 125 psi. Some of the super heavy RV trailers are being equipped with dual axle quad tire configurations. (No telling what kind of a mess any inside tire is going to make when/if it fails).


For Tireman9: For some reason probably only known by manufacturing engineers the tires provided on the RV trailer - especially heavier ones - just don’t perform as expected. And it’s not just the ST tire. There are known LT tires provided as OE that fail just as frequently. The dynamics of a free floating (fifth wheel) trailer bobbing and weaving down the road at highway speeds is just not computing. I’m a firm believer that it’s not just a tire manufacturing problem. Over a couple of years of high mileage use I kept increasing my tires load range until I got to a point where they quit failing. The increase was more than 500# per tire. All tires were ST. I weigh my RV trailer often and am never over the GAWR on any position but still had to get to a 20% reserve above GAW before my failures quit happening.


FastEagle

[RustyJC]

Quote:

Originally Posted by RustyJC In my case, after two (2) tread separation failures I moved from the OEM Goodyear G614 RST tires (LT235/85R-16G rated 3750 lbs @ 110 PSIG) to the Michelin XTA (215/75R-17.5J rated 4605 lbs @ 125 PSIG) with new 17.5" J-rated aluminum wheels.

As a correction, the current Michelin XTA spec sheet rates this tire at 4805 lbs @ 120 PSIG. See HERE

Rusty

[FastEagle]

Quote:

Originally Posted by RustyJC As a correction, the current Michelin XTA spec sheet rates this tire at 4805 lbs @ 120 PSIG. See HERE Rusty

The speed rating for the XTA you have will stop most people from using it because tires with speed ratings lower than 65 MPH cannot be adjusted upwards.

The information to support that statement can be found in the current Michelin Truck Tire Data Book or Service Manual located in the reference provided below.

Michelin Americas Truck Tires Reference Materials Page

FastEagle

[RustyJC]

I'm aware of the speed rating issue - this is a European tire where a 100 kph maximum speed limit for trucks translates to approximately 62 MPH. Coincidence??

Internal heat buildup, the primary root cause of most tire failures, is a function of a number of variables, with two that we can control being load and speed. Load determines how much a specific cross sectional plane of the tire flexes per revolution at a given air pressure. Speed determines how many flex cycles per unit of time the tire is subjected to. The subject tire is rated to perform satisfactorily at 4805 lbs load (@ 120 PSIG) at 62 MPH. Since my application loads this tire at approximately 3200 lbs per tire (66.6% of rated load) and I run the 120-125 PSIG cold inflation pressure (the current Michelin data sheet notwithstanding, 125 PSIG is shown on the sidewalls of my tires), I don't feel uncomfortable at all running these tires at 65 MPH interstate cruising speeds with excursions to 70 MPH as might be required. In other words, I'm 33.3% below rated load and (at 70 MPH) 12.9% above the rated speed.

Performance to date bears out this pore ole broke down mechanical engineer's thumbnail technical analysis....no failures, and one can comfortably lay the palm of one's hand on the tire tread immediately after pulling off the Interstate on a 100+ degreeF ambient temperature day.

Another factor leading to my selection of the XTAs is my experience with Goodyears on the three (3) 5th wheels that we've owned - 2 failures on 15" Marathons, all 4 tires showed signs of tread separation and were replaced; 2 failures on 16" G614s, all 4 tires declared defective and replaced. Conversely, I've used Michelin XPS Ribs on a previous 5th wheel and the Michelin XTAs on our current 5th wheel with no problems and little heat buildup. Therefore, I feel more comfortable with the XTAs than I do with either of my 75 MPH rated Goodyear options (the 16" G614 RST or the 17.5" G114 LHT). I wonder....has anyone heard of a speed-related failure of an XTA??? I know I haven't, and they've been available as standard equipment or options on higher-line 5th wheels for awhile now.

At the end of the day, ya pays yore money and ya takes yore choice. I could have bought either the Michelins or the Goodyears when I upgraded to the higher load rated 17.5" tires and wheels. I'm happy with my choice, but you need to feel comfortable with yours. Either way, I wish you many miles of trouble-free RVing and no tread separations.

Rusty

[Tireman9]

Quote:

Originally Posted by FastEagle As the RV trailer industry ventures deeper into larger and heavier models the tire industry is seeking to provide tires to this market by increasing load capacities in the smallish tires needed for the cumbersome fifth wheel trailers...... snip For Tireman9: For some reason probably only known by manufacturing engineers the tires provided on the RV trailer - especially heavier ones - just don’t perform as expected.....snip FastEagle

Fast. I certainly can't speak for all RV mfg or all tire companies but I have not seen any evidence of RV Mfg and especially those that are making 5vers, are working with tire mfg company engineers to ensure the proper tire is used. Having spent a good part of my career developing tires for specific car & LT applications with a little time on HD Truck companies, I can assure you that simply picking a tire out of a price list is not the way to be sure you get the correct tire for a given application.

I doubt that many tire company engineers would recommend a tire application with much less than at least a 10% “Reserve Load” but when I look at the realities of RV usage I see Reserve Loads closer to 1 or 2%.

The high c/g and sway of TT certainly would suggest that increasing reserve load would be very desirable. BUT that means the RV mfg would need to spend a few more bucks when it comes time to buy the wheels and tires. It also assumes that there are even experienced Engineers involved in the design & development process.

Based on inspections of just a few RVs, I see no evidence of a competent vehicle development engineer having been involved in the process.

Maybe if the RV mfg had some stake in the quality of what they sell (as with a more realistic 3 to 5 year warrantee) and had to consider warrantee claim costs when designing the RV, we would see better quality and more durable components selected, not just the cheapest that will function for a few months.

[FastEagle]

Whenever I post information about RV trailer tires or those being used on the RV trailer I try very hard to stick to the facts as written by the rules makers. I try to reference the most current documents available on the internet or other reference materials I am using. Normally I just write the comment without posting a lot of references. When posting about a specific tire Manufacturer I consult with their tire information.

The following statement is verbatim from the Michelin Tire Service Manual, page # 9 and the Michelin Tire Data Book, page 89. Both of these references are dated 2010.

“The Tire and Rim Association inc. (TRA) permits operating a 65 MPH rated tire at higher speeds with reduced load and increased inflation. No such permission is granted by the TRA for tires with speed ratings below 65 MPH.”

At one time Goodyear applied this truck tire ruling to also include the ST tire. They have since rescinded that decision.


FastEagle

[RustyJC]

I provided the technical rationale behind my decision. You can accept it or not.

After 36+ years with an engine manufacturer in technical and engineering management positions, I'm quite aware who has primary responsibility for product brochure content, and unfortunately the marketing, product liability and risk management groups have as much or more input than the engineers.

If the sum total of what I wanted to know about tires was what's in a brochure, then the trailer-specific, RV-service-approved Goodyears would look terrific. Personally, I take that information and combine it with actual user experience, which is what I'm sharing - after all, that's the mission of this forum, "Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts." My user experience with the Goodyears is that they don't provide acceptable reliability, so I'm sharing my experience concerning alternatives I've selected that have proven to be reliable.

When all is said and done, what I have done, am currently doing or will do in the future and my rationale behind my decisions may have no value in your personal decision-making process, but it might help someone else in theirs.


Rusty