The problem is the tire formulation. RV tires...are notorious for being made 'soft'. This allows the kind of sidewall flexing that RVer's like because of the nice smooth ride. But it also causes early sidewall failures. In addition, the softer rubber composition is often blamed for that type tires lack of UV tolerance.
As a result of these issues, many RV'ers will refuse new tires from a dealer if it's older than a few months. Especially if we've specifically told them we wanted NEW tires no more then 6 months old.
And then there is the problem of RV tires just sitting for months at a time. A 'RV' tire doesn't tolerate that very well. Especially if it's already been sitting in a warehouse for years prior to mounting on an RV.