Inner Tube 80/100 &ndash; 21 TR4 Straight Valve Stem - Fits on these Tube Type Tires: 80/100-21, 80/90-21, 90/80-21, 90/90-21, 100/80-21, 3.00-21 Motorcycle Inner Tube 80/100-21 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: 80/100-21, 80/90-21, 90/80-21, 90/90-21, 100/80-21, 3.00-21 Heavy duty durable valve stem. Unbeatable performance and value.