How come this is such a big deal with the motorhome RV crowd?
Accordingly ... why isn't this an issue with all the SUV's, pickups, Priuses, cross-overs, smart cars, etc.. being driven all over this country?
My pickup had 12-13 years on it's last set of tires and I finally replaced them solely due to tread wear. I got 6 years on my last set of motorhome tires and replaced them solely due to side-wall cracks - which I consider a completely unnecessary thing to have happened to them had the design been what it should have been in the first place.
Now ... TT and 5'er tires are something else again. Some of those type RVs are very heavy and they're riding on small diameter tires for their weights. This translates into a lot of internal tire material breakdown from the internal heat generated by a small diameter tire turning fast while carrying a lot of weight.