S&M's trail tire available in wire bead only with a mid weight, high pressure casing. The 2.1 has a micro knurled surface on a directional tread designed to go on the rear. It features a center tread with a V-notched edge for accelerating and a flat edge for braking. The 2.425 front tire size is a nod to the old 2.125 Comp III we grew up riding in the front. Additional angular raised sections on three rows of knobs help keep the larger Mainline dialed in the front!