Motorhome tires 'age-out' before they wear out. OTR trucks wear out the tread because of high miles then get the tires re-capped with new tread. It is my understanding that our RV tires do have compounds that can extend the life of the tire (and reduce UV damage to sidewalls) but those compounds are released by rolling and flexing. Since many motorhomes sit more than they move, sidewalls crack and the tire ages out well before we ever experience much treadwear.
I also understand that you can cut a deal with some dump truck haulers to buy your older RV tires (22.5's). It seems they will use them on their tag axles. I know I will try that when I need to replace my tires.
'07 Country Coach Allure 470 Siskiyou Summit #31578, Cummins ISL 425; 2014 Ford F150 toad; Air Force One Toad Brake.
Glen Allen, VA; Smith Mountain Lake, VA.