The wheels of a skateboard come in a lot of different sizes and hardness. These wheels are made of a rubber like material called urethane. The size and hardness of the wheels have an effect on the easiness of the ride on a skateboard, how fine it handles, as well as its velocity. Skateboard wheels are usually 52 mm to 60 mm and include their own ball bearings fitted. Street skateboard wheels are typically very hard, which let them to decelerate f...