Spitfire Formula 4 Classics 99DU

Spitfire Formula Four 99DU Wheels are skateboard wheels manufactured in sets of four from Spitfire Formula Four urethane with a 99DU (99a) durometer hardness, constructed in a Classic shape with a medium-width contact patch and smooth surface finish. These wheels are available in multiple diameters commonly including 52 mm, 53 mm, 54 mm, 55 mm, 56 mm, 58 mm, and 60 mm, with corresponding width and riding surface dimensions that scale with size (for example, a 52 mm wheel typically has ~32 mm width and ~15.5 mm riding surface). Formula Four urethane is a 100 % pure urethane compound designed for abrasion and flat-spot resistance and higher rebound, and the Classic wheel shape is a non-symmetrical profile with a medium contact patch for street, park, and transition skateboarding.