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).
Recommendation by Dunlop and Michelin to abandon the use of security bolts for tyres, especially cord tyres.
| Identifier | ExFiles\Box 45\1\ Scan280 | |
| Date | 1st August 1922 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} c. to EP.{G. Eric Platford - Chief Quality Engineer} X4050 Hs{Lord Ernest Hives - Chair}3/LG10. 8.22. SECURITY BOLTS FOR TYRES. X4050 The Dunlop Co. have now followed the lead of the Michelin Co. and are fitting no more security bolts to tyres and recommend that the use of security bolts should be abandoned especially with cord tyres. The shape of the bead for the cord tyre is different to that used on the canvas tyre and it makes it that the security bolts used on the canvas tyres are useless on the cord tyre because, owing to the change of section, they grip the cover at a point where they can be of very little use. Also if the standard type security bolt are used with the cord tyre, there is a very great risk of the tube getting underneath and becoming chafed and deflated. The Dunlop Co. claim that no tyre can come off the rim as long as there is reasonable pressure in it. When a tyre is deflated the security bolts have very little hold on the tyre and in the case of the cord tyre with standard security bolts, they would be useless. The Dunlop people admit that it would be possible to make a security bolt suitable for the cord tyre but do not see how it would be possible to ensure that it was used with the right tyre. The position at present is that we are fitting security bolts to all tyres and the Dunlop and Michelin Co's are recommending that they are not used. There have been cases in which Rolls-Royce owners have had trouble with their tyres coming off the rim contd:- | ||