Why do we need both wheel size and tire size limits? Isn't a tire size limit enough?
Especially as the wheel size limits are hit and miss. In STU, the tire is limited to 265 or 285mm and the wheel "limited" to 11 (recommended maximum wheel for a typical 285 tire is 11", for a 265 only 10.5"). STR & STX both have a max wheel size of 9", but they have different max tires sizes (255 vs 265). And the STX (& STH) max tire size is 9" which is generally the absolute minimum for the class legal 265mm tire. Meaning you have minimal wheel options if you want to run the max tire (which you do).
So some subclasses have wheel size limits that are not a constraint, and others have ones that are a very restrictive constraint. Why? We should at least target the middle of the recommended wheel size range for a given tire. Which would take the STX & STH wheel max to 9.5 or 10".