I have read the article on the Explorer ST build for the Ford Racing School using the 21" SV503 wheels. They use the 315/30ZR/21. Does anyone know if there is a specific offset or wheel spacer size used with that wheel/tire setup? I would think not, since it's built for the race track, but I don't know...I'm wondering how much room there is left inside between chassis/frame and tire and also edge of fender. Also wondering if that car deals with rubbing issues and limited steering turns, if there is any? That wheel size seems to be above what a lot of people are calling 305 being the widest you can run. I would love to have that ford racing setup with my H&R lowering springs. My goal is to fill the wheel well full of the widest sticky rubber possible, without rubbing and turning issues. How did Ford do it with their racing school build???