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).
Calculation of the running costs for Dunlop tyres.
| Identifier | ExFiles\Box 81\1\ scan0145 | |
| Date | 12th April 1919 | |
| R.R. 1/S (20 H) (X 828. 12.4.19) G 2506. X990 Tyre Costs. 2 Dunlops. cost. £19. 38 Mileage 3500. Cost per mile 1.3d per mile. per tyre. .65. | ||