For Sale Are Two Brand New Motorcycle Inner Tubes Fitted With a TR4 Straight Metal Valve. These tube will fit the following sizes: 2.25-19 2.50-19 2.75-19 3.00-19 Inflation of inner tube can be achieved using a standard car foot pump as our tubes are fitted with a schrader type valve as used on car rims and wheels. Our tubes are made from high quality butyl rubber, which is a synthetic rubber unlike natural rubber which is porous and  leaks under pressure. Butyl is air-tight and will out last the natural rubber inner tube.