The Maxxis Larsen TT is a proven XC winner and a favorite of pro dual slalom racers. Its closely-spaced, small-block tread pattern hooks up in hard conditions thanks to a consistent contact patch, while the ramped profile on the knobs makes for fast rolling through the straights. A wide range of sizes and durometers mean the Larsen TT can hang on both coasts, and the eXCeption version features an ultralight 120 tpi case for race day.Tire Durometers: Higher the number the harder the compound, softer durometers grip better, but wear out faster70a: Hardest compound for maximum tire life, lowest rolling resistance62a: Medium compound for improved traction, low rolling resistance, will wear out faster than 70a60a: Better traction, higher rolling resistance3C: (Triple Compound) hard center compound for low rolling resistance and long life, progressively softer compounds on the edges for higher grip when corneringExc: (eXCeption Series) Combination of 62a compound and a 120 TPI (threads per inch) casing, 120tpi offers lower rolling resistance, higher flexibility(better handling) and lighter weight - recommended for racing.UST - Universal Standard for Tubeless - use in conjunction with UST rims