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).
Standardisation of Dunlop tyre treads for the Phantom III and 20/25 HP models.
| Identifier | ExFiles\Box 157\1\ scan0311 | |
| Date | 18th April 1936 | |
| X1332 W/S - Cx.{Major Len W. Cox - Advertising Manager} from Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}10/KW.18.4.36. Tyres for Phantom III & 20/25 HP. Referring to Cx.{Major Len W. Cox - Advertising Manager}15/KW.17.4.36, and Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}14/KW.8.4.36. You are wrong in assuming that we are proposing to standardise the chamfer Dunlop tread on the Ph.III. Some confusion appears to have arisen with regard to the three Dunlop tyres which we have had on test. These tyres are as follows :- (1) The latest type Dunlop "90". This tyre is the worst for noise. It has strengthened buttresses which support the edge of the tread, and additionally has a flatter tread than previous Dunlop tyres. (2) The original Dunlop "90" tyre. This was the 90 tread as used on our cars up to about 12 months ago, and had no strengthened buttresses on the edge of the tread. It is definitely better for tyre groans than (1). As it has now been superseded in the Dunlop range we have had to give it a special name, and have called it the Dunlop Fort R.90. (3) The chamfered tread tyre, which is (2) with a large proportion of the edges machined away. This is a great deal quieter than the other two tyres and is what we understand you have been running on some 20/25's in London, and is what we are proposing to run in France on an experimental test on Ph.III and the 20/25. From the conversations we have had with the Dunlop Rubber Co. up to the present we have no indication that they have agreed that we should standardise these tyres. Apart from the life, on our limited tests its adhesion seems to be a doubtful factor. You will therefore see that there is no question of the Dunlop people having agreed to the chamfered tread being standardised on the Ph.III and not on the 20/25. We are meeting Mr. Healey of the Dunlop Rubber Company next week to discuss the question of a completely new type of tread to meet our requirements. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||