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. detailing the drawbacks and rejection of their 7' x 21' tyres after testing.
| Identifier | ExFiles\Box 45\2\ Scan171 | |
| Date | 16th September 1929 | |
| C. to By.{R.W. Bailey - Chief Engineer} film X4050 Expl. Dept. Hs{Lord Ernest Hives - Chair}/An. 2/WJ. September 16th.1929. The Dunlop Rubber Co., Fort Dunlop, Erdington, BIRMINGHAM. Dear Sirs, For the attention of Mr.Bond. We have now had an opportunity of testing out the 7" x 21" tyres which you recently sent us. Our conclusions are that there are a number of drawbacks to these tyres which prevent us from adopting them. Briefly the outstanding objections are - (a) They make the steering unpleasantly heavy for shunting owing to the increased width of the tread, and probably owing to the fact that its depth allows the rubber to get a better grip on the surface. (b) They make the steering heavy and uncertain up to 30 miles an hour. (c) They spoilt the selectivity of steering at higher speeds. (d) The steering lock is affected and decreased owing to the increased width of the tyre. (e) The chassis weight on the set of six tyres is increased by 36 lbs. In addition to these permanent objections, there is the commercial objection at present that the rear spare wheel carriers will want altering. Our main endeavour at the moment is to make our car suitable for the 7" tyre on the 21" rims. We therefore consider it highly improbable that we shall ever adopt the 7" tyre to the 21" rims. Yours faithfully, | ||