Tiago Lemos Pro Formula Fours. Classic Shape, 99A Duro. Spitfire Formula 4 features more speed and control on all surfaces, unmatched flatspot resistance, smooth anti-stick slide, high rebound compund. 100% true performance urethane. Classic Shape: The number 1 wheel shape in skateboarding. Medium width riding surface with round sidewalls. Designed for control in all situations.