The Specialized Ground Control Grid 2Bliss Ready 27.5 inch Tyre is an exceptionally versatile trail tire. CAD engineered knob shapes strengthen knob structure for optimum braking and traction, but keeps knob surfaces adaptable for best ground control. GRIPTON compound helps make this the perfect choice for epic trail rides in any condition. We recommend GRID tires for anyone seeking the utmost in flat and sidewall protection. Specialized Ground Control Grid 2Bliss Ready 27.5 inch Tyre Features Bead: Foldable Butyl wrapped bead = 2Bliss Ready Compound: GRIPTON 650b x 2.1; psi 25-50; approximate weight 735g 650b x 2.3; psi 25-50; approximate weight 795g 650b x 2.6; psi 20-40; approximate weight 880g