RV Tire Safety: Why don’t more big tire companies make ST-type tires?

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with RV tire expert Roger Marble
I was asked by a fellow RV owner if I could recommend a tire for their trailer. He said: “We have asked why the major tire companies other than Goodyear (e.g., Bridgestone, Michelin, Hankook and Continental) don’t carry ST tires, but they didn’t really provide a direct answer. Just sort of danced around it. I have been reaching out and trying to find an ST provider, but have not had any luck so far.”

My reply: In my opinion, none of the “major” tire companies are interested in the RV trailer market (ST-type tires) because of the documented poor level of weight and inflation management. Goodyear Tire Company pushed for the introduction of Special Trailer tires back in the late ’60s and early ’70s at a time when 20-foot single-axle trailers pulled with bumper hitches were the norm. A 1/2-ton truck was rarely an option for average family use vehicles.

ST tires were offered with increased load capacity, i.e. lower cost to the RV company. To compensate for this, the 65 mph max speed and reduced tread depth was presented as required and sufficient to allow the bias tires of the day to wear out in maybe 10,000 to 15,000 miles. Many times P-type passenger tires were applied to these smaller RV trailers but a -10% load capacity adjustment to the P-type load capacity was required.

The 1974 national 55 mph speed limit kept operating speeds down so tire failures were still at a lower level. But with the introduction of steel-belted radials to the tire marked coupled with the growth of trailers to 35+ feet and tire mileage theoretically increased to the 30,000- or 40,000-mile range, the tires no longer wore out but started to fail at an unacceptably high rate.

The annual tire market in the U.S. is 200 million a year for passenger-type tires and about 37 million for LT type. Annual sales of all types of RV is very volatile and ranges from 160,000 to 500,000 a year for all types, from Class A down to teardrop. Some industry information suggests only 20% of the RV market are “conventional RV trailers,” so that would translate to a market of 400,000 tires in the best years.

When looking at the tire market, I think we can see little incentive for a company to go to the effort and expense of developing tires for a market that is only 0.5% of the P- and LT-type tire market. This is especially considering the high level of warranty claims and problems due to the extremely poor maintenance record seen from RV owners.

BUT … back to the original question. The only ST tire that I was able to look at a section of recently was a Goodyear Endurance. It looked like it might perform better than some other ST tires I have looked at.  But the only performance data I have is just the reports on various RV forums where customers seem happy with the Endurance.

Sorry to say that your choice is relatively limited if you have to stay with ST-type tires. While Maxxis and Cooper have supporters, you might be better off switching to LT-type as long as you make the required adjustments for load capacity by increasing physical size and or Load Range. If you follow my blog you should have already seen THIS post of the topic of LT- vs. ST-type tires.

 

Read more from Roger Marble on his blog at RVtiresafety.net or on RVtravel.com.

 ##RVT957

 

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billh42
3 months ago

Roger,

I know that you are not necessarily a fan of ST rated tires but the last time I needed tires for my 15000 pound (measured gross weight) fifth wheel trailer my tire dealer recommended the Carlisle CSL 16 High Speed ST235/80R16 (G) tire. They have a 4080 # rated load at 110 psi. They are speed rated for 81 mph (I tow between 60 and 65). And of course you need the wheels and valve stems for G rated tires.

I’ve so far put a little over 5000 miles on these tires and I could not be more pleased with the performance. They run cool even in 90 degree temps, are wearing evenly and track like they are on rails. Some people would say it’s a bit of overkill but I like the extra load and speed cushion they give me.

I would definitely recommend them to anyone looking for a high performance heavy duty ST trailer tire. What are your thoughts on this?

Roger Marble
3 months ago
Reply to  billh42

Yes I do hear that the “G” rated tires seem to be doing OK. I think these are more like actual truck tires and some are even steel bodied. They do cost more than the 14″ & 15″ Load Range C & D St type tires found on many trailers. I have also seen some 17.5″ LR-F truck tires on larger trailers. But the RV companies need to provide sufficient space for these larger truck tires or the options for tires gets limited.