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 plotting tire load against inflation pressure for various 4-ply tire sizes.
| Identifier | ExFiles\Box 170\3\ img180 | |
| Date | 9th December 1938 guessed | |
| LOAD 1000 800 600 400 200 0 INF #/IN² 18 20 22 24 26 28 30 32 4 PLY 6.00 5.75 5.50 5.25 5.00 4.75 955# 860# | ||