Thursday, November 30, 2023


Are ST tires the “best” tires made?

RV Tire Safety

with RV tire expert Roger Marble

One fact that many choose to ignore, or just don’t think about, is that very few RVs have the axle load evenly split between axles on trailers or end-to-end on any one axle. Some owners have learned that there can be upwards of 500 lbs. to more than 1,000 lbs. load unbalance.

It takes more work and effort to learn the reality of your RV tire loading. I, and others, have covered the how and where to learn the loads on each individual tire (usually not on CAT or similar truck scales).

Regulations are written based on the assumption that RVs have close to perfect weight balance but few owners will make the effort to learn the actual tire loads. Also, those sacred regulations fail to tell the trailer owners that they can expect to need to replace ST tires at 3 to 5 years usage based on the tire DOT serial.

You will see numerous complaints about tire failures but most can be traced to overload/underinflation and over-speed or other external damage. There is no “magic” rubber in tires with “ST” on the sidewall, but many seem to want to believe there is.

As a tire engineer I have yet to have anyone explain why or how ST tires should be expected to perform better than any other tire of the same size on the road. Yet that is what some would have you believe based on their insistence simply because a tire company makes such an ST tire with greater capacity than their premium LT line. Where is the tire company that makes an ST tire, that will offer a warranty on their ST tires comparable to what they offer on their premium P or LT tires?


Read more from Roger Marble on his blog at



Roger Marble
Roger Marble
Retired Tire Design and Forensic Engineer w/50+ years of experience. Currently has Class-C RV. Previous Truck Camper, Winny Brave, Class-C & 23'TT. Also towed race car w/ 23' open trailer and in 26' Closed trailer. While racing he set lap records at 6 different tracks racing from Lime Rock CT to Riverside CA and Daytona to Mosport Canada. Gives RV and Genealogy Seminars for FMCA across the USA. Taught vehicle handling to local Police Depts



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Captn John (@guest_42191)
4 years ago

For that reason I run Sailun 235/85/16 tires at 110 psi on my 5er. The loaded weight has always been under 14,500 ~~ gvwr 15,200 ~~. No way to go over 4400# per tire.

Dave Telenko (@guest_42063)
4 years ago

You were saying that regulations were written based on the assumption that RV’s have close to perfect weight distribution! About 8 months ago, before our Alaska vacation, I decided to get my wheel nuts torque checked & get it weighed. I did this at one of Petes tires locations in Gardena Ca. To my amazement all lug nuts were ok at some crazy number like 475#. When they weighed each corner on their scale & gave me the weight, my front passenger weighed 1200 pounds more that the driver side @ 4060 (D) & 5260 (P) & the rear was almost exactly the same on each side 9200 (P) & 9100 (D)= 27,620. We were totally loaded with all tanks full, except the black & gray that were empty. My factory Freightliner tires are at their max @110 PSI. Thats based on about 4600 lbs. on each tire.
My question is how do you set the pressure when your already maxed out on the pressure. What can be done about the regulations that would control such a miss-match of weight?

Dave Telenko (@guest_42261)
4 years ago
Reply to  Dave Telenko

Let me ask is there actually regulations on weight distribution? Are the Rv manufactures required to follow guide lines for proper weight distribution?

Roger Marble (@guest_42264)
4 years ago
Reply to  Dave Telenko

Dave, I’m sorry to say your only options are to move stuff around in the RV or remove some of the stuff you currently carry or get tires with higher load capacity. That might also mean new stronger wheels. I don’t know of anything you can do about the sloppy regulations. You can file a complaint with NHTSA and if enough people did that they might consider a rule update but that takes years and the RV companies would oppose any change. IMO Tire load capacity should be at least 115% of GAWR with 125% a safer solution.

Roger Marble (@guest_43215)
4 years ago
Reply to  Dave Telenko

I am not aware of any regulation for weight distribution

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