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).
Explaining the decision to standardise 5¼' tyres on the 20 HP model.
| Identifier | ExFiles\Box 53\2\ Scan297 | |
| Date | 27th November 1926 | |
| 4565 To BJ. from Hs.{Lord Ernest Hives - Chair} c. to PN.{Mr Northey} c. to Sg.{Arthur F. Sidgreaves - MD} Hs{Lord Ernest Hives - Chair}3/LG27.11.26. 20 HP. TYRES. 45820 The chief reason why 5¼" section tyres have been standardised for the 20 HP. is because we did not wish to make too big a jump at one time. Also the advantages of a 6" tyre over a 5¼" tyre are very small, in fact for standard we consider the 5¼" preferable. In order to obtain any increased comfort from the larger section tyres, they must be run at a lower pressure. At present with the 5¼" section we run at 35 lbs. - the 6" tyres would have to be run at 30 lbs. With the 30 lbs. pressure on a 6" tyre, the steering would be heavier and there would be more tendency for the car to roll. The steering lock would also be reduced a small amount with 6" tyres. We had in mind at the time we adopted the 5¼" tyres that the 6" fits the same wheel so that if at any time we wished we could easily go to the larger section tyres. Hs.{Lord Ernest Hives - Chair} | ||