If you are using the stock wheels, as the fronts and rears are different widths, you can not go with the same width tire of different width wheels and expect to have the exact same total diameter so..either go with the 11s and the 9s or go the extra mile and get all new wheels and go square(all the same tires). I would..and will if I ever wear-out these Reapers...and I will go with a wheel that gives me the offset I need to delete the wheel spacers...which are killers of ball joints, wheel bearings, rear knuckle bushings and some a-arm bushings