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).
And comparing the mileage and wear of different tyre types.
| Identifier | ExFiles\Box 42\1\ Scan095 | |
| Date | 28th November 1927 | |
| c. from CWB. c. to Hs.{Lord Ernest Hives - Chair} c. to FN. X3809 CWB7/CP28.11.27. re. Tyre Mileage. The figures of Hs{Lord Ernest Hives - Chair}/AJL1/LG17.11.27. are not in accordance with our experience so far of wellbase wheels and low pressure tyres as used under Sales conditions on trials cars and, of course, of the Inspection Department. The average mileage of the old 33 x 5 s.s. cord tyre was 12,000 to 14,000 miles, whereas the 33 x 6.75 W.B. tyres, so far discarded for various reasons, have only averaged 7,000 miles. It is probably necessary to discard the 6.75 tyre in some cases for our purposes, before it is completely worn out, as when the pattern becomes worn off these tyres tend to cause severe skidding, but I do not think that the mileage left in them, when this state is reached, will amount to more than 2,000 or 2,500 more miles. CWB. | ||