The Purgatory GRID tire is the standard bearer for trail tire performance. By applying FE Analysis & our GRIPTON compound to the Purgatory weve optimized this tread to be fast rolling & to bite hard on loose terrain. Meanwhile the GRID casing provides the utmost in cut & flat protection at the sidewalls & of course the 2 Bliss Ready design is the icing on the cake allowing you to run lower tire pressures & all but eliminate the risk of pinch flats.> Casing: Additional sidewall protection for exceptional durability plus sidewall stiffness for stability.> Bead: Foldable> Butyl wrapped bead = 2 Bliss Ready> Compound: GRIPTON> 650b x 2.6; psi 20-40; approximate weight 940g