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 selection and alternatives for the 34-EX Nairobi Run.
| Identifier | ExFiles\Box 114\4\ scan0124 | |
| Date | 2nd June 1937 | |
| 89 1011 S/W. Rm.{William Robotham - Chief Engineer} 34-EX - Nairobi Run. CxIO/KW2.6.37. Mr. Symons tells us that in connection with the selection of tyres for this trip you showed him a specially large tyre which he describes as approximately 8½" for 18" wheel, which, when fitted to a wheel and placed upon the axle of one of the experimental cars, revealed the fact that beyond the wing clearance being insufficient there were no technical objections to fitting these tyres. In a memo which you wrote to Sg{Arthur F. Sidgreaves - MD} during the preparation of this car you said :- " The largest tyre we could fit without major modifications " is the 7½" on present standard 18" rim. Having no " personal experience of desert work we do not know " whether this section of tyre will be adequate. The " only alternative is to fit twin wheels. This however " could not possibly be accomplished in the time available. It would however seem from the above that twin wheels were not the only alternative if what Mr. Symons says is correct. Therefore, would you please let me know what were the reasons which led you to discard the 8½" tyre above referred to. Mr. Symons points out that whilst the area of contact with these bigger tyres was not necessarily as great as the area of contact with the 7½" tyres with low pressures, the 8½" tyre would have given an increased ground clearance which would have been beneficial. I would be very glad, therefore, if you would let me know the reason why these bigger tyres were not specified for this job. Cx.{Major Len W. Cox - Advertising Manager} Lwb. | ||