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. concerning high-speed bounce and wobble in tyres due to imbalance issues.
| Identifier | ExFiles\Box 28\4\ Scan247 | |
| Date | 30th June 1925 | |
| Y457 C. Mailing Dept. C. Hd.{Mr Hayward/Mr Huddy} C. Hs.{Lord Ernest Hives - Chair} C. MX.{John H Maddocks - Chief Proving Officer} BY6/H.{Arthur M. Hanbury - Head Complaints} 30.6.25. June 30th, 1925. Tuesday Messrs The Dunlop Rubber Co., Ltd. For the attention of Colonel Matthew, Fort Dunlop, Erdington, Birmingham. Dear Sirs, TYRES. ----- Referring in the first place to the combined high speed bounce and wobble which we experienced when using balloon tyres, we have been very surprised lately to find similar effects coming up very definitely with standard tyres under normal pressures. An investigation of the subject shows that although in 1911 we made special arrangements that the joint of the inner tube should be opposite the valve with the object of keeping the inner tube as nearly in balance when inflated and on a wheel as possible, we were surprised to find when investigating the matter that all tubes are now being supplied with the joint only one foot measured along the tyre from the valve, thereby bringing the valve and the joint of the inner tub almost on the same diameter, making a distinct out of balance as the result of these two masses occurring at this point. We found in our investigation that the wheel plus tyre varied as much as from 6 ounces minimum out-of-balance to 12 ounces maximum out-of-balance, an average of 9 ounces, which is unquestionably far too great an amount of out-of-balance to be permitted on a high speed automobile front wheel. In our opinion the out-of-balance on one complete wheel and tyre should never exceed more than three ounces measured on the inside rim diameter where the spoke nipples are. Contd. | ||