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).
Tyre and wheel specifications, rolling radius, and clearances for the 25HP model, including requests for new wheel sets for testing.
| Identifier | ExFiles\Box 179\1\ img047 | |
| Date | 26th October 1931 | |
| Dx FROM DA{Bernard Day - Chassis Design}/EV.{Ivan Evernden - coachwork} HS.{Lord Ernest Hives - Chair} Copy to SC L'ORIGINAL DA{Bernard Day - Chassis Design}/EV{Ivan Evernden - coachwork}1/W26.10.31 25HP. TYRES AND WHEELS. x 5820. x 5910. We thank you for BY4/G191031. and HS{Lord Ernest Hives - Chair}/FW5/AD231031. We do not wish to raise an argument unnecessarily over a thing which has been done, and which it is obviously a fault of our primitive recording system that we have not appreciated it. We do not however understand how it is that although you say the silent tyre of 14.52 rolling radius was never actually supplied, on the whole of the chassis prints for R.{Sir Henry Royce} and S. series - F.56806. and F.57097. - an ordinary silent tyre is indicated, actual size 31.4", rolling radius 14.52". After this the Fort tyre appears to be called for but there is no change in the wheel arch clearances. We also do not understand the statement in BY4/G191031. that the dia. of the Fort silent tread is only .250" greater than that of the ordinary silent tread. According to the figures which you give the dia. appears to be approximately .750", and the rolling radius approximately .500" greater. As far as the 25HP. is concerned for the moment we are leaving things as they are, but on the special touring saloon for R.{Sir Henry Royce} which we hope may be the forerunner of a type of car, we would like to use 18" rims, and would be glad if you could send a set of such rims to Park Ward as soon as possible so that they may be suitably stove enamelled or fitted with discs to match the colour of the car as this car has no black on it. With these rims the rolling radius will apparently be back to where we were with the ordinary silent tread. If the tests of the 18" rims are satisfactory on 25HP. we shall wish to use them on J.{Mr Johnson W.M.} 3. and so obtain the height of car which our drawing indicated. We therefore think that you should obtain two sets of these wheels - one for R's car, and another for the test on a Pullman limousine. We are aware that some modification will be required to the cross steering tube to enable 18" rims to be used on J.{Mr Johnson W.M.} 3. DA{Bernard Day - Chassis Design}/EV.{Ivan Evernden - coachwork} | ||