Even 245 is sometimes too wide for a 7" rim, but check what the manfacturer's recommended rim sizes are for that particular tire. (for example see the difference between what the generic charts said 68's specific measurements for the E70 Coker tire). My defination of too wide being distorting the tread surface and sidewalls, thereby reducing the potential maximum traction of the tire. That said, that doesn't mean a tire won't physically fit on a rim which could be another definition.