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).
Data table showing tyre rolling resistance at various speeds, loads, and inflation pressures.
| Identifier | ExFiles\Box 158\1\ scan0224 | |
| Date | 12th October 1938 guessed | |
| Speed m.p.h. Inflation Pressure lbs/in.sq. Tyre size 7.00-18.00 Load 17 cwts. Rolling resistance lbs/ton. Tyre size 7.00-18.00 Load 15 cwts. Rolling resistance lbs/ton. Tyre size 6.50 -17.00 Load 15 cwts. Rolling resistance lbs/ton. 30 40 26.1 23.0 25.4 35 30.7 31.2 31.7 30 32.9 32.9 35.3 25 36.4 39.7 37.6 50 40 29.9 28.7 29.5 25 42.6 - - 70 40 33.2 31.3 31.1 35 35.6 35.7 38.9 30 40.5 43.4 45.0 25 51 47.4 54.1 Tyre Size. Road Load. Inflation Pressure lb/in.sq. Rolling Resistance. at 30 mph. lbs/ton. Rolling Resistance. at 50 mph. lbs/ton. Rolling Resistance at 70 mph lbs/ton. 6.50-17.00 15 cwts. 40 25.5 29.5 31.1 7.00-18.00 15 cwts. 36 28.3 - 36.8 7.00-18.00 17 cwts. 40 26.5 30.9 34.7 Covers conditioned by 2 hour preliminary run at 30 m.p.h. Top ply temperature 55° - 60°C. Accuracy of repetition 5% at 30, m.p.h. 10% at 70 m.p.h. | ||