The ground control grid 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 protectiongt bead foldablegt butyl wrapped bead 2bliss readygt compound griptongt 650b x 23quot psi 25