Premium Service inner tubes are manufactured to the highest quality. This tube is for ATV, UTV and 4 Wheeler tire applications. This tube will work in Bias ply tires ONLY. The size marked on the tube may differ from the size needed as most inner tubes are made to stretch in order to fit multiple tire sizes, according the manufacturer this tube will fit on the following tire sizes: 18x8.50-8, 18x9.50-8, 21x12.00-8, 18.5x8.5-8, 18.5x9.5-8