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 the Dunlop Tyre Company disagreeing with the high pressure of 70 lbs moulded onto their supplied tyres.
| Identifier | ExFiles\Box 39\2\ Scan140 | |
| Date | 1st May 1922 guessed | |
| COPY. DUNLOP TYRE COMPANY. On the 32 X 4½ S.S. tyres you have lately supplied us with, there is moulded in the cover - "Keep inflated to 70 lbs. pressure - Load 1200 lbs." We should like to point out to you that the car on which these tyres will be fitted will frequently only weigh 3000 lbs. We have purposely gone to the expense of fitting ample size tyres in order that we run with low tyre pressures. We are absolutely opposed to high tyre pressures - we have already put our views on this matter before you in connection with the 33 X 5 tyres. All the cars we have running with the 32 X 4½ straight-sided tyres are running with the pressures considerably below your specification. We are running from 40 to 50 lbs. pressure. We have completed about 30,000 miles and we are satisfied that for all-round satisfaction, these are approximately the best pressures. We cannot state too emphatically that the tyres pumped to the pressure you state, are useless for the car we wish them for. For your information we attach herewith a copy of tyre pressures suggested by the Michelin Co. in connection with the 895 X 135 tyres. These pressures agree with our experience and are satisfactory to us for the 895 X 135 tyres. We consider it unwise to mould on the cover of the tyre pressure - consideration must be given to the load it has to carry. We should like to hear from you how you propose the question of tyre pressures should be dealt with. It would appear very inconsistent for Messrs. Dunlop to mould on to the tyres 70 lbs. pressure and for R-R to tell the users of their cars fitted with these tyres to only use 40 or 50 lbs. pressure. It would not satisfy us - for tyres supplied to us only should have the pressures omitted because the trouble would come up when new tyres were fitted. (Hs.{Lord Ernest Hives - Chair}) Yours faithfully, | ||