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 different tyre sizes (32 X 4½ vs 820 X 120) and their effect on vehicle ground clearance for the 40/50 HP model.
| Identifier | Morton\M1.1\ img019 | |
| Date | 19th August 1921 | |
| Contd. lis2/L.C19.8.21. -2- ------------------ 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 is 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 showing 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} R.R. 235b (100 T) (S.H. 798. 10-12-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2948 | ||