Why the differences in expected tire life based on type of usage?

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RV Tire Safety

with RV tire expert Roger Marble

Question: I saw a recent question on a forum regarding tire life:


“I was wondering if someone could cover a topic regarding travel trailers, 5th wheels, buses, semi’s and semi trailers, and anything recreational: What is the tire life for them?  I have never seen this covered. Hmm!”

Answer: I have covered this in a few different posts on this blog and some RV forums but this post may put it all in one place.

Generally, tire life for buses and HD trucks is based on wear, not time, as these vehicles may drive 50,000 to 100,000 miles a year, with the tires wearing out at 50,000 to 80,000 miles.

Daily drivers (cars  and pickups) drive about 12,000 miles a year and may get 3 to 5 years of life – again, mostly based on wearing out.

With RVs (trailers and motorhomes), mileage might be as low as a few hundred miles a year to a few driving up to 20,000 miles a year. But if you consult your owner’s manuals you will probably see them point out expected life to be 3 to 5 years on trailers. Motorhomes probably hit 7 years to the suggested max of 10 years – again, before wear-out due to low miles driven in most cases.

The primary reason for the earlier “end of life” on trailers is the result of the unique radial belt shear forces identified in this blog and in the industry technical papers as “interply shear.” Interply shear comes from a combination of tires being dragged rather than steered around corners, and tires “fighting” each other when going around corners as the tires on different axles are not all rotating around the same center of the turn.

It is the interply shear that initiates the cracks between the belts and accelerates the crack growth that can end up as a belt separation before the tires wear out. The interply shear damage is augmented by damage from improper (low) inflation, improper (high) load and, in some cases, excess heat due to speeds higher than the basic design called for.

I hope this helps explain why we have different tire life experiences with our RVs than with our cars.

##RVT895

 

xxxxx

 

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

 

 

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