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).
Rubbing of a straight rib tyre tread pattern.
| Identifier | ExFiles\Box 158\1\ scan0187 | |
| Date | 8th June 1938 guessed | |
| 1339 STRAIGHT RIB TREAD. | ||