Yimatzu 80/100-12 (3.00x12) inner tube (innertube) with TR4 straight valve stem. Most commonly (though not exclusively) associated with 50cc, 70cc, 90cc, 110cc, 125cc, 140cc, 150cc , 155cc and 160cc dirt bikes / pit bikes / motocross. Most commonly used as the rear wheel tube in 12 inch rear / 14 inch front configurations.