The Ultimate Wheel 52mm X 30mm Wide Set of Four wheels, contact 14.5mm X-Formula rolls over rough terrain like softer wheels do, but slides much like a harder wheel will. Speed: X-Formula™ is extremely fast because it has a super high rebound. X-Formula will slide when you ask it to, and grip when you need it most developed over a ten year period to optimise performance and fine tuned to perfection, It has been developed using the highest quality, longest lasting materials. Wheel Core None Wheel Diameter 52mm Wheel Width 30mm Wheel Hardness 97a Wheel Formula XF Wheel Colour White Wheel Suggested Use Street Wheel Surface Smooth Wheel Shape V6 Bones X-Formula V5 Sidecut X97A Skateboard Wheels Natural 52mm