Bike Master Heavy Duty Motorcycle Tube Bike Master Heavy Duty Tubes are designed to perform on the track or the trail. Whether you ride hard-pack or sand, the natural rubber compounds of the BikeMaster Heavy-Duty tubes are durable. With increased wall thickness, these tubes provide better puncture and pinch flat protection to keep you riding. Features: Tr-6 Straight metal stem type (8mm dia) Heavy Duty wall thickness Natural rubber tubes, with heavy duty valves Center metal valve unless otherwise noted Tubes are sold each