Ricta Wheel Dynamics 54mm Maurio McCoy Geo Pro Naturals White Slim featuring 99a high performance urethane for maximum speed, smooth roll, and fewer flat spots. Ricta's lightweight Slim shape features a thinner profile for minimal drag and a medium width riding surface for smooth, predictable slides. Wheel Diameter (Millimeters) 54.1 Wheel Durometer/Hardness 99a Road Surface (Millimeters) 19.1 Wheel Shape Slim Wheel Width (Millimeters) 31.3 Ricta Geo Naturals McCoy Slim 99a Skateboard Wheels - 54mm