Comparison photograph of two different tire tread patterns, labeled MA1 and MA2.
| Identifier | ExFiles\Box 171\2\ img058 | |
| Date | 12th June 1932 guessed | |
| MA1 MA2 | ||
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).