Tire rules are as follows. Hoosier M-30 26.5/8.0-15 - M-30 27.5/8.0-15 - Hoosier M-60 27.5 - Optional right rear only. American Racer Stocker medium 26.5 8.0-15sw - American Racer Stocker Medium 27.5 8.0-15sw - American Racer Stocker Hard 27.5 8.0-15sw Right rear only. No grooving, No Needling, No removal of material. you may grind and sipe.