For your shopping...we can't speak to the topic of tires that aren't the OEM size or brand...so, about the Michelin XRV's
If you have a Costco or Sam's Club with a tire sales...they had the best price we could find anywhere on the OEM Michelin XRV's - (Matched size/date, but Loose/Unmounted).
If you don't have a big box store, go to one of the shops in your nearest town that services commercial (Class 6, 7, and 8) trucks. Ours had the XRV's for only $25 more than CostCo.
The next step is mounting. Our CostCo didn't have the right equipment for 22.5's. The commercial truck shop (Parkhouse) here mounted all 6 and balanced the fronts for $150 total for 6. I have been told by several sources that they don't usually balance the rears.
Why pick the XRV's over other brands? UV light damage. Michelin touts the best compound in the tire to fight UV damage. And since RV's rarely wear out before sidewall cracks or checking exceeds the maker's safety recommendation, it is important. This, we know is true, because the original rear inner tires mounted in '06, were found to be in perfect condition when replaced at only 47,000miles & 11 years old.