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 comparing the tractive resistance of standard tyres versus balloon tyres at various speeds.
| Identifier | ExFiles\Box 53\2\ Scan052 | |
| Date | 31th May 1923 | |
| 45 LBS / □" INFLATION STANDARD TYRE. 30 LBS REAR 25 LBS / □" FRONT BALLOON. TESTS 49 G B. TOTAL CAR T.R. LBS PER TON. M.P.H. TRACTIVE RESISTANCE COMPARISON 49/50. 33x5 STANDARD TYRES 33x6 BALOON TYRES W.A.R. 31.V.23 104/5/2 | ||