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).
Wheel and tyre sizes for the S.S. car and their impact on steering performance.
| Identifier | ExFiles\Box 65\2\ scan0297 | |
| Date | 28th May 1929 | |
| To DA{Bernard Day - Chassis Design}/EV.{Ivan Evernden - coachwork} from Hs.{Lord Ernest Hives - Chair} c. to R.{Sir Henry Royce} Sg.{Arthur F. Sidgreaves - MD} X7820 Hsl/LG28.5.29. X7810 [crossed out] X7820 The size of wheel which has been instructed and ordered for the S.S. car has a 21" rim. Comparative tests have frequently been made and it has always been proved that with the smaller wheels we have more steering troubles. The steering on 18-EX car when it returned from France fitted with these wheels, could not be considered satisfactory. The position may be reviewed again now because the Dunlop people are proposing to alter their standard size of tyre. The present 6.75" tyre is to be superceded by the 7" section tyre. We have got a sample set of these tyres and tests will shortly be made; but any alteration in the size of the S.S. wheels can only be looked upon as a possible future improvement. HS.{Lord Ernest Hives - Chair} | ||