Air Loc Brand Tire Inner Tube with TR13 Rubber Valve Stem - 6 inch 13x5.00-6, 13x6.50-6 13x5.00x6. 13x6.50x6 Combination Size Fits Sizes: 13x5.00-6, 13x6.50-6 Tube has Standard TR13 valve stem: Straight rubber valve, the most common stem style, measuring approx. 1.38" long and used in the standard size wheel hole of approx. 1/2"