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).
Graph comparing horsepower losses in new versus worn tyres under load at various speeds and inflation pressures.
| Identifier | ExFiles\Box 158\2\ scan0025 | |
| Date | 2nd May 1939 | |
| 4 AVON TYRE LOSSES. COMPARISON OF TYRES NEW (SHEWN ——) WITH TYRES HAVING ¼ THE TREAD REMAINING (SHEWN -----) CURVES AT FULL THROTTLE UNDER LOAD. WEIGHT ON 2 TYRES TESTED 1920 LBS APPROX. H.P. LOST IN TYRES M.P.H. FIRST AND ONLY RUN WITH NEW TYRES 35 LB/IN² 22 LB/IN² 44 LB/IN² 35 LB/IN² RM{William Robotham - Chief Engineer}/TAS{T. Allan Swinden}/2-5-39 | ||