Bones Wheels All-Terrain Formula Mudder Fudder White Skateboard Wheels - 54mm 80a (Set of 4) BONES WHEELS ATF Wheel Mudder Fudder Black 54mm 4pk. All-Terrain Formula (ATF) wheels are poured in a special soft urethane we call All-Terrain Formula or (ATF). ATF wheels are excellent for rougher terrain so regardless of road quality, this revolutionary formula will roll you there quickly and smoothly.