Wheel Shape / Profile: Conical Full – Conical refers to the cone shape produced by using flatter surfaces from the contact patch to the side of the wheel. Double Conical wheels were a popular shape in the late 1970’s. It either referred to a conical shape being used on the corner & from the wheel side to the bearing seat or a conical profile on both sides of the wheel. In recent years this shape has been modified to suit smaller hard wheels. It provides a nice shaped corner for slides, flatter wheel sides to lock into edges and wider contact patch. The Conical Full is around 2 to 3mm wider than it’s straight conical partner if you are looking for a little more grip and slide control over speed.
Urethane – Formula Four 99A: Spitfire released their new Formula Four wheels a few years ago now. The latest formula was designed for higher abrasion resistance. This means it is a little harder to flat spot. Formula Four 99A wheels are generally decorated with a blue themed graphic. Unless of course it is one of the signature wheels. The signature wheels feature artwork custom designed for each rider. 99A is considered a softer wheel in the modern skateboarding scene. They are still very hard. The 99A formula will provide a little more grip on super smooth surfaces and is a little more forgiving to ride on rougher surfaces.