| 4–10 June 1955|
| Geoff Duke|
| Isle of Man Tourist Trophy|
Snaefell Mountain Course (Senior and Junior)
Clypse Course (Ultra Lightweight, Lightweight, Sidecars, Clubmans Senior and Clubmans Junior)
Mountain Course 60.72 km (37.73 mi);
Clypse Course 17.63 km (10.95 mi)
1955 Isle of Man TT Wikipedia
In the 1955 Isle of Man TT the Lightweight 250cc race moved to the 10.75 miles long Clypse Course, also used for the Lightweight 125cc TT race, and the Sidecar TT, and the course was used for these races until 1959. During this period the rest of the TT program remained on the Mountain Circuit.
In the Junior TT, Norton rider Bob McIntyre led for four of the seven laps, but brake overheating and suspension problems forced him to slow, allowing Bill Lomas on a Moto Guzzi to pass, and go on to victory.