List of weights for different tyre and wheel combinations.
| Identifier | ExFiles\Box 158\1\ scan0036 | |
| Date | 10th November 1927 guessed | |
| X20 WEIGHT OF TYRES. X4050 / X3725 31 X 6.00 tyre fitted on 19" wheel. 57 lbs. 5¼" tyre fitted on 21" wheel. 59 lbs. 33 X 6.75" tyre fitted on 21" wheel. 73 lbs. --------- | ||
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).