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 showing horsepower losses in tyres at full throttle for each gear.
| Identifier | ExFiles\Box 158\2\ scan0047 | |
| Date | 17th May 1939 | |
| 10 TESTS ON 2 REAR WHEELS ON DYNO DRUMS LOSSES AT FULL THROTTLE IN EACH GEAR NEW DUNLOP FORT TYRES WITH APPROX. THE SAME AXLE LOAD OF 1920 LBS IN EACH CASE. Y-AXIS: H.P. LOST IN TYRES X-AXIS: M.P.H. 1ST GEAR 30 LB/IN² 2ND GEAR 31 LB/IN² DIRECT 32 LB/IN² OVERDRIVE 34 LB/IN² | ||