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).
Specification sheet detailing wheel size, engine revs, and axle/overdrive ratios.
| Identifier | ExFiles\Box 161\1\ scan0053 | |
| Date | 10th November 1937 guessed | |
| 5. With the standard 5.500" x 18" wheels and maximum engine revs 4300 R.P.M. an axle ratio of 2.85 to 1 is necessary, or a 3.73 to 1 axle ratio and an overdrive of 1.31 to 1. | ||