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).
Recommended tyre pressures for 20 HP cars, considering high speed wobbles and Dunlop Company's advice.
| Identifier | ExFiles\Box 39\2\ Scan182 | |
| Date | 8th December 1925 | |
| X3538 BY3/H.{Arthur M. Hanbury - Head Complaints} 8.12.25. c. Hs.{Lord Ernest Hives - Chair} TYRE PRESSURES. ------------ Referring to BJ12/N. 25.11.25. and BJ4/H.{Arthur M. Hanbury - Head Complaints} 4.12.25. both on the above subject, I have discussed this matter with Hs.{Lord Ernest Hives - Chair} and after giving the matter careful attention, he does not consider that he can drop the pressures below those specified in my memo BY3/H.{Arthur M. Hanbury - Head Complaints} 17.11.25. which were fixed up in conjunction with Hs.{Lord Ernest Hives - Chair} Hs.{Lord Ernest Hives - Chair} is of the opinion that we have gone as low as we dare, taking into consideration the question of high speed wobbles, his opinion being that we must maintain the 50 lbs. minimum figure for front tyres as specified in the memo quoted above. We are distinctly of the opinion that it would be wrong to have a lower pressure in the back tyres than the front, as this would at once raise a doubt in the customer's mind as to why he should not have as low a pressure on the front as the rear, and we should have to meet such a question by explaining that there was a liability for high speed wobbles; the more we can keep off this subject the better, in dealing with our customers. In regard to the 20 HP. cars, we agree at the Works with the recommendations put forward by Sales, namely, Open Cars. Front Tyres 40 lbs. ------ Rear Tyre 40 lbs. Closed Cars. Front Tyres 40 lbs. ------- Rear Tyres 45 lbs. We would like to point out in passing that these pressures are considerably below those recommended by the Dunlop Company, and it would therefore appear advisable for us to submit the pressures in question to the Dunlop Company before finally incorporating them, the main reason being that we are below our previous figures, which are again lower than the Dunlop Company's recommendations. BY.{R.W. Bailey - Chief Engineer} | ||