From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparing tyre sizes (32 x 4½ vs 820 x 120) and their effect on vehicle ground clearance for the 40/50 HP model.
| Identifier | ExFiles\Box 180\M1\1\ img019 | |
| Date | 19th August 1921 | |
| Contd. -2- Hs{Lord Ernest Hives - Chair}2/LG19.8.21. which means that the car will be .5" higher off the ground if we use the 32 X 4½ instead of the 820 X 120. 32 X 4½ in the same size rim as we are using on the present 40/50 H.P. Attached to Mr. Royce's copy of this memo. is a photograph shewing two Michelin wheels - one fitted with the beaded edge tyre 820 X 120 and the other fitted with the straight sided tyre 32 X 4½. Hs.{Lord Ernest Hives - Chair} | ||