Skateboard wheels are essential components that affect a skateboard's performance and ride quality. Typically made from urethane, these wheels come in various sizes and hardness levels. The diameter of the wheels, usually ranging from 50mm to 60mm, influences speed and stability, while the durometer rating indicates how hard or soft the wheels are, affecting grip and shock absorption. Choosing the right wheels depends on the type of skating you plan to do. For instance, street skating often requires smaller, harder wheels for tricks, while cruising or longboarding benefits from larger, softer wheels that provide a smoother ride over rough surfaces.