| Location | Douglas, Isle of Man |
|---|---|
| Time zone | GMT |
| Major events | RAC Tourist Trophy |
| Length | 37.5 miles (60.39 km) |
| Turns | 219 |
| Race lap record | 1 hour 32 mins, 32.2 sec (57.70 mph) (Major Henry Segrave, Sunbeam, 1922) |
The Four Inch Course was a road-racing circuit first used for the 1908 Tourist Trophy Race for cars,[1] held on public roads closed for racing by an Act of Tynwald (the parliament of the Isle of Man). The name of the course derives from the regulations for the 1908 Tourist Trophy adopted by the Royal Automobile Club, which limited the competitors' engines to a cylinder-diameter of four inches. The Four-Inch Course was adopted by the Auto-Cycle Club for the 1911 Isle of Man TT Races. The Four-Inch Course was subsequently known as the Snaefell Mountain Course or Mountain Course when used for motor-cycle racing.