We are here in the Dallas are and we have a 99 Diplomat that needs tires. The size presently on the coach (all around) is 225 70R 22.5, but looking at the Michelin program and calling around to a few of the big truck tire shops no one seems to have the exact size available. One service center said the size is no longer manufactured, and they are looking for one size larger the 235 70R 22.5, and haven't found anything yet. I looked at using the 255 70R 22.5, and the height (diameter) will be close, but the added width will not fit in rear wheel wells when the coach is off of the airbags. One RV repair facility said to use the larger 255 70R 22.5 and they said it is OK for the coach to rest on the tires when it is stored, but my fear is if I'm trying to level the beast and it tips the coach up and down on the tires it will eventually cause a problem. I called Monaco Tech Support in Oregon, and they only show the one size tire that is acceptable for the coach, the smaller 225 70R 22.5.