TWO-18X8-50-8-20x8-00-8-20x10-00-8-tire-Inner-Inner-Tubes-FAST-SHIPPING TWO NEW 18X8.50-8 TUBE HEAVY DUTY HIGH QUALITY COMMONLY USED IN LAWN TRACTORS, GO CARTS, OUTDOOR EQUIPMENT ENTER QUANTITY DESIRED 1=2,2=4 ETC. FAST FREE SHIPPING TR 13 VALVE IS STRAIGHT RUBBER VALVE The TR13 valve is the most common stem style, measuring approx. 1.38" long and used in the standard size wheel hole of approx. 1/2"