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 Rubber Co. Ltd. regarding the standardization of wheels and collective experience with straight-sided tyres.
| Identifier | ExFiles\Box 45\1\ Scan212 | |
| Date | 20th June 1921 | |
| X4050 X4050 X3895 Hs{Lord Ernest Hives - Chair}7/LG. 20th. June 1921. Messrs. The Dunlop Rubber Co.Ltd., Aston Cross, Birmingham. Dear Sirs, For the attention of Mr. Paull. We are about to standardise the Dunlop Wheels with the demountable rims and straight-sided tyres. We should like to give you our collective experience with straight-sided tyres generally. Apart from the tyres of your make we have test - Goodyear, Goodrich, United States Royal Cord, Kelly Springfield and Firestone tyres. Also the Rolls-Royce Company in America have been using nothing else but straight-sided tyres for years past. We find that we can appreciate the difference in the riding of the car owing to the less inherent friction with the cord fabric compared with the woven fabric. Our opinion is that a woven fabric tyre is the most comfortable on the R-R Car. The comfort, however, is bought so dearly owing to the difference in the life of the tyres, that it cannot be considered. We have found that the average mileage on the rear of the car weighing 52 cwts. with cord tyres is 4100 miles. We have found very little difference in the mileage obtained from Dunlop, Goodyear, Goodrich and Kelly-Springfield tyres. The great advantage we have found in the straight-sided cord tyre is the freedom from bursts. With all the cord fabric tyres we have run, we have never had a single burst until the tread has practically worn away. This is a very different experience to what we had with the Magnum woven fabric tyres. One frequently got a burst with those tyres before they had completed 1000 miles and before the tread was worn at all. We have a very big scrap heap of old covers which is very instructive on this matter. We notice, on the latest set of straight-sided tyres we have received from you that there is stamped on them "the pressure should be 80 lbs.". We do not agree with this contd:- | ||