Michelin Bib Mousse Front Tube - 90/100-21 22513 Made from a multi-cellular butyl material, Bib Mousse replaces conventional tubes, providing a pressure equivalent of approximately 13 psi Specifically designed for off-road competition use, at speeds up to 80 mph (130 km/h) - above this speed, heat buildup can lead to rapid destruction of the Bib Mousse, resulting in serious injury to the rider - under no circumstances should Bib Mousse be fitted to motorcycles for on-road use Bib Mousse may be used only with Michelin off-road tires, including StarCross HP4, StarCross MS2, StarCross MH2, S12, M12, H12, Enduro Comp III, EnduroStar, Baja and Desert - because Bib Mousse is shaped for a perfect fit inside these Michelin tires (see sizing chart below); use of Bib Mousse with other brands of tires can lead to handling instability and possible destruction of the Bib Mousse Each Bib Mousse includes a tube of Bib Mousse Fitting Gel; installer must be sure to follow installation instructions supplied with the product