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).
Graph of tyre load in pounds versus inflation pressure in pounds per square inch for various tyre sizes.
| Identifier | ExFiles\Box 170\3\ img178 | |
| Date | 7th December 1938 guessed | |
| LOAD - LBS. 1000 800 600 400 200 0 INF. #/IN² 20 22 24 26 28 30 32 34 36 4 PLY 4 PL 4.75 5.00 5.25 5.50 5.75 6.00 4.5-17 860# 955# | ||