Avon Venom-R 250 / 40R-18 M/C 81V Radial Tubeless 3-Ply Motorcycle Rear Tire Introducing The Avon Cobra ChromeAvon Venom-R 250 / 40R-18 M/C 81V Radial Tubeless 3-Ply Motorcycle Rear Tire. This will fit many years, makes and models of bikes. Avon Venom-R 250 / 40R-18 M/C 81V Radial Tubeless 3-Ply Motorcycle Rear Tire.