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 on blueprint paper showing performance data for different axle and tyre configurations against speed.
| Identifier | ExFiles\Box 183\M22\ img078 | |
| Date | 1st May 1921 guessed | |
| AXLE 16 x 52 Back Axle 15 x 52 Back Axle 14 x 52 (TYRES) MILES PER HOUR. 35 40 45 50 55 60 65 70 75 | ||