Michelin Bib Mousse Tube Replacement Front 80/100-21 90/90-21 Made from a multi-cellular butyl material, replaces conventional tubes, providing a pressure equivalent of approximately 13 psi (0.9 bar). Specifically designed for off-road competition use, at speeds up to 80 mph (130 km/h). Above this speed, heat build-up 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. Because Bib Mousse is shaped for a perfect fit inside Michelin tires, use of Bib Mousse with other brands of tires can lead to handling instability and possible destruction of Bib Mousse. Each Bib Mousse includes a tube of Bib Mousse Fitting Gel. Be sure to follow installation instructions supplied with the product.