Well gotta take into account different wheel offsets too. To be safe i would have the fenders be at least an inch wider than the tires that way there is room for different wheel offsets and so on. Id hate to have it done and the tire still be sticking out past the fender or flush with it to where when you brake the fender comes down onto the tire. Again just make sure there is more than enough room. Im using a 24.5X9X13 m/t slick as well as most others on here running slicks on big turbo cars. I have them on some weld 8" wide wheel