13.6-38 Tractor Tube – TR218A Valve Stem – Heavy Duty Agricultural Inner Tube13. 6 38 Inner Tube TR 218A Heavy Duty Tractor Tire Tube Reliable Air Retention for Tractor and Agricultural Tires The 13. 6 38 inner tube with TR 218A valve stem is designed for heavy duty agricultural and tractor applications. Manufactured from high quality rubber compounds, this tractor tire inner tube provides excellent air retention, durability, and consistent performance under demanding field conditions. Built for Heavy Duty Agricultural