As you might know from reading threads pertaining to tires on iRV2 and other RV forums, many of us replaced our OEM Michelins with Toyo. Toyo is probably the most popular replacement brand but I also like Yokohama, Sumitomo, and Hankook. I've always been partial to tires from these and other Japanese-based manufacturers and more recently, South Korean manufacturers like Hankook.
Just because they're tires from Japanese companies, it doesn't mean that is where they are made. They can be made in a variety of locations around the world. Yokohama now makes just about all their commercial truck tires at their plant in Mississippi. Sumitomo is also transitioning to making their commercial truck tires in the U.S.
We've often had heated arguments through the years on this forum over Michelin vs non-Michelin brands. Many of us don't believe in paying the premium prices for Michelins. Some, however, believe only buying Michelin and strongly believe that any other brand is putting their family at risk ...in other words, Michelin is the only tire that is safe. I call B.S. on that.
But back to your situation ...like I say, Toyo seems to be the most popular brand to replace the OEM Michelins. If you do a search on this forum, you'll see that many are very happy with Toyo. Toyo was the OEM tire for Monaco coaches for awhile.
The 255/80R 22.5 is proprietary to Michelin. The closest size will be 265/75R22.5
Toyo M154 is what most will use to replace their OEM Michelins. Toyo M154 in 265/75R22.5 is highly recommended and you'll save a lot of money compared to buying Michelins again.
Toyo M154 description