Inner Tube 2.75/3.00-21 TR4 Straight Valve Stem - Fits on 90/80-21, 90/90-21, 100/80-21 Motorcycle Inner Tube 2.75/3.00-21 TR4 Valve Stem* TR4 Valve Stem: Centered, Straight Stem, Round Shape to fit on rims with a round valve base. Fits on these Tube Type Tires: 90/80 - 21, 90/90 - 21, 100/80 - 21 Heavy duty durable valve stem. Unbeatable performance and value.