Higher levels of ruggedness for offroad racing and riding. The Dunlop Geomax AT81 offers exceptional all-around performance, as well as a high-durability compound that resists block chunking and tearing. Shoulder knobs with lateral grooves provide additional biting edges and allow for more flexibility and impact absorption. Front tire inspired by the highly popular D756. RC (Reinforced Construction) RC (Reinforced Construction) sizes boast 4-ply construction for enhanced puncture and cut resistance. EX ( Endurocross) The EX was developed for use in Endurocross racing and has a unique "gummy" compound giving exceptional grip in extreme conditions.