Specialized's Purgatory GRID tire is the standard bearer for trail tire performance. By applying FE Analysis and our GRIPTON compound to the Purgatory, they've optimized this tread to be fast rolling and to bite hard on loose terrain. Meanwhile, the GRID casing provides the utmost in cut and flat protection at the sidewalls, And of course, the 2Bliss Ready design is the icing on the cake, allowing you to run lower tire pressures and all but eliminate the risk of pinch flats.