Bridgestone X40 Hard Terrain Front Tire - 80/100-21, Position: Front, Rim Size: 21, Tire Application: Hard, Tire Size: 80/100-21, Tire Type: Offroad 003091 Rear tires feature cooling fin for better heat dispersion Convex Castle for enhanced traction in acceleration and braking Asymmetric rear tread pattern also enhances traction during acceleration, deceleration and cornering Improved grip in all conditions Available in most big bike sizes