Conical Full Shape. With a wide riding surface and a cutaway design, this shape has unmatched control and lasting speed everywhere. Formula Four Urethane Formula Four urethane is unlike any other. Both in the streets and under high-speed stress tests in Spitfire's lab, Formula Four wheels retained more material, coned less and kept their original shapes and sizes longer than any other wheel. Wide More traction and stability at high speed so you'll be less likely to slip out of your line. Surface Smooth wheels have less surface friction than treaded wheels and are easier to slide. Classic Shape: The #1 shape in skateboarding worldwide - proven for speed and control.