Specially-designed 2WD/4WD rear tires with 12mm internal hex. The center countersunk area was indeed redesigned to position the wheel nut much deeper. Precision fit, ideal for high-competition racing. Made out of versatile, durable item to withstand effects. The medial side of wheel is aerodynamic for optimum performance. Special options that come with the wheel are visible through inside: reinforcement ribs to make the tires as stable as possible and expel deformation.