Challenge, Gravel Grinder, Tire, 700x42C, Folding, Clincher, Vulcanized, Nylon, 120TPI, BlackMake your mark on the gravel scene with the Gravel Grinder. This tire combines a fast rolling diamond center with aggressive shoulder knobs that only hook up when the terrain gets soft, muddy, or a bit sketchy. This clincher with 120TPI nylon casing provides both performance and durability. Includes PPS, a Puncture Protection System placed between the tread and casing to increase resistance to punctures. Brand: Challenge Model: Gravel Grinder Length: