What does 7mm or 8mm mean ? Those refer to the inner diameter of the bearing and the size of the axle its going on. Most of the new skates use 8mm axles so the standard 8mm bearings would be needed.The older models, and high end
What is a typical inline wheel size and hardness? A typical inline wheel diameters are from 70-110 mm, with larger wheels enhancing speed and smaller wheels being designed more for maneuverability.
Softer wheels are good for outdoor use and provide