Spitfire Formula 4 Conical Full 99DU skateboard wheels are a set of four wheels manufactured from Formula Four urethane with a 99DU (99a) durometer hardness and a Conical Full shape, featuring a wider riding surface and cutaway sidewalls to increase contact patch width and reduce weight. They are available in multiple diameters including approximately 52 mm, 53 mm, 54 mm, 56 mm, and 58 mm, with corresponding widths and riding surface dimensions that scale with size (e.g., a 54 mm wheel typically has a ~34 mm width and ~22 mm riding surface). The wheels have a smooth surface finish and are constructed to resist flat spotting and retain their shape and dimensions over time using a 100 % pure urethane compound with a high-rebound formulation. They are designed for use in park and street skateboarding where a harder, durable wheel is specified.
