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 low and medium pressure tyre sections and proposing new standard sizes for the Phantom and 20 HP models.
| Identifier | ExFiles\Box 53\2\ Scan279 | |
| Date | 23th October 1926 | |
| To B.J. from Hs.{Lord Ernest Hives - Chair} c. to R.{Sir Henry Royce} c. to Wor.{Arthur Wormald - General Works Manager} c. to BY.{R.W. Bailey - Chief Engineer} X4565 Hs{Lord Ernest Hives - Chair}1/LG23.10.26. LOW PRESSURE AND MEDIUM PRESSURE TYRES. X4565 X4050 Replying to BJ13/E22.10.26. We have found the makers description of tyres most confusing. We find the most convenient method is, to call the tyre by its section because, after all, it is the section of the tyre which decides on the pressure it can be run at. For instance, for the Phantom the present tyre is 5" section, the one we propose to adopt is 6.75" section. There is also a tyre made which is 6" section. The Michelin people make a 6.2" section tyre which fits on to the same rim as the 6.75" Dunlop tyre. From a comparison of the tyre sections, it is easy to see at a glance the relative tyre pressures. We recommend that our description of the tyres is known as :- Phantom Present standard 5" section straight-sided. Proposed standard 6.75" " well base. 20 HP. Present standard 4 1/2" section straight-sided. Proposed standard 5 1/4" " well base. We are ascertaining what other makes and sizes of tyres can be used on these rims so that, although we may not recommend them, they might be used if the standard tyres are not available. Hs.{Lord Ernest Hives - Chair} | ||