Graph showing tyre losses in horsepower versus speed for various tyre types and pressures.
| Identifier | ExFiles\Box 158\2\ scan0022 | |
| Date | 2nd May 1939 | |
| I TYRE LOSSES AT RATED PRESSURES CURVES OBTAINED AT PART THROTTLE UNDER NO LOAD I.E. DYNO CLUTCH OUT WEIGHT ON 2 TYRES TESTED 1920 LBS APPROX. H.P. LOST IN TYRES M.P.H. INDIAProduction 20 HP. with 4-speed box and Front Wheel Brakes (NEW) 34 LB/IN² DUNLOP FORT (NEW) 34 LB/IN² DUNLOP FORT (WORN) 34 LB/IN² AVON (WORN) 35 LB/IN² MICHELIN PILOTE (NEW) 27 LB/IN² DUNLOP TRACK RACING (NEW) 45 LB/IN² RM {William Robotham - Chief Engineer} / TAS {T. Allan Swinden} / 2.5.39 | ||
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).