Continental Grand Prix 4000s II Cycling Tire Updated Black Chili tread compound with carbon nano particles delivers 26% lower rolling resistance, 30% more grip and 5% longer mileage, plus it's self-cleaning Vectran Breaker belt is lighter and tougher than aramid belts, 5x stronger than steel and resists water, punctures and cuts 3-ply casing and 330 TPI provide additional reinforcement Tread wear indicators help you gauge the true life of the tire, eliminating premature replacement or overuse