THIS IS FOR ONE FACTORY SPEC TIRE Single radius profile to provide the ultimate control characteristics for when the track conditions deteriorate and become rougher to race. Advanced Apex on the Factory Spec provides a larger apex for improved responsiveness and increased support for higher speeds and harsher landings. Proprietary Ultra-High Molecular Mass compound features extended polymer chains that increases bonding points with the carbon molecules to deliver a rubber that is extremely strong allow the knobs to penetrate the ground more effectively.