A lot of cars run different size tires front and back, my freinds car has 18in AMG monoblocks. I don't remember the exact size's but the rears are wider by a lot (I think like 285 vs 245) and have a smaller side wall(35-40) than the fronts, the outside's are the same diameter. I wouldn't run tires that are differant diameters that could cause problems.

__________________
2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200