Ok, I have spent a few hours researching this. The tire size I am looking for is 255/80R22.5. I look at the 11 page Michelin RV tires by MSPN and get 8 choices for that size with an invoice price range from $331.77 to $503.10 (most are in the $339 range). How do I sort this out for what to buy? Four are tread pattern XZE and four are XRV. I hate to be stupid, what am I missing?