A lot of guys will run up to a 28" tall drag tire on 15" wheels in the rear with 17" wheels in the front for a dedicated track set-up. Race Star wheels are pretty common as are the Weld RT and RTS wheels. I would take a look in the 2011-2014 Mustangs section for more details. I know on some 15" rear applications a swaybar relocation kit is needed.