Rear tread block shape and distribution plus flexible knobs help the tire penetrate down through the surface dirt for extra traction across a broad range of off-road applications Developed for use in Endurocross racing and has a unique "gummy" compound, giving exceptional grip in extreme conditions Endurocross tires offer more all-around performance plus higher levels of ruggedness for off-road racing and riding "Plush pad" recess design between tread blocks enhances compliance for bump absorption and rider comfort Lateral grooves on shoulder knobs provide additional biting edges and allow the knobs to be more flexible Rear center blocks are arranged in-line to provide a larger contact patch for maximum traction High wear-resistance tire compound offers enhance chipping, tearing and wear resistance Rear tire carcass features two nylon plies M-rated for speeds up to 81 mph. TIRE AT81EX 110/100-18