by Todd Martin
Skateboard wheels are fastened as a pair at the base of a skateboard, held and mounted in place by unique axles known as trucks. They are usually made from polyurethane, a very hard variety of rubber, and vary in size between 48 to 100 millimeters. In addition to size, skateboard wheels besides differ in hardness, as measured by a durometer A scale. The softest ones are at about 75a, though the hardest skateboard wheels are at 99a. A few are also branded to have ratings of 101a and beyond nevertheless this is improper because the durometer A scale merely runs up to 100. For skateboard wheels harder than the hardest skateboard wheels for the A scale, B or D scales are typically used for better precision and wider option of hardness.
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