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).
Letter to Dunlop Rubber Co. regarding safety issues with demountable tyre rings coming off wheels on experimental cars.
| Identifier | ExFiles\Box 45\1\ Scan284 | |
| Date | 10th August 1922 | |
| X4050 HS{Lord Ernest Hives - Chair}4/LG. 10th. Aug. 1922. Messrs. The Dunlop Rubber Co.Ltd., Aston Cross, Birmingham. Dear Sirs, For the attention of Mr. Paull. We have had two cases with our experimental cars running in France of the demountable ring used on the straight-sided rims coming off when the tyre is punctured and the ring has been lost. In one case it occurred on the 32 X 4 1/2 tyres and wheels which you supplied to us only 3 months ago - in the other case it occurred with the 33 X 5 tyres and wheels you supplied to us about 7 months ago. We have, of course, had other wheels which have been punctured whilst the car has been running at high speeds on which the ring has not come off. Tests we have made show that after a certain speed with a flat tyre, the demountable ring opens out due to centrifugal force and the tyre also draws away from the ring due to the same force so that there is nothing to prevent the ring from coming off. We think the risk for the demountable ring coming off the rim is a very real trouble and we consider that some form of locking device is desirable for perfect safety. We are prepared to agree that some of the locking devices increase the difficulty of changing the tyre so much that it is better to be without them. After a user of straight-sided rims, however, has spent an hour or so in fields and ditches looking for the ring, he is firmly convinced that he would the sooner have a beaded edge contd:- | ||