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).
Design drawing of a tire tread pattern with area calculations.
| Identifier | ExFiles\Box 29\4\ Scan238 | |
| Date | 25th March 1917 guessed | |
| A (circled) 5.50/17 R 3.25/17 R 36 lbs 11 Cwt Load TOTAL AREA - 26.00 SQ. INS GROOVE " - 8.58 " SOLID " - 17.42 " N.S. EDGE - .77 | ||