Abstract: An ATV endless track conversion using sprocket rings fit over each of the tires of the rear wheels which are inflated into a tight driving connection. A swing arm extension is pivoted to the ATV swing arm and has its own spring-shock absorber suspension in addition to the existing ATV spring-shock absorber. A return idler wheel set is mounted at the rear of the swing arm extension as well as two track band shaping wheel sets which engage track band upper and lower segments forward of the idler return wheel set to maintain the track band tension and footprint without substantial friction losses.