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).
Road test report detailing the performance of Michelin tyres, focusing on steering feel, ride comfort on pavé roads, and necessary wheel modifications.
| Identifier | ExFiles\Box 146\1\ scan0225 | |
| Date | 30th March 1938 | |
| SrI/ET.30.3.38 - 2 - was asked to close his eyes and admitted not having realised that we had negotiated a bend. This is due to several causes, probably the most important being the lack of any tendency on the part of the car to lean over on one side or the other, and secondly the absolute lack of tyre screech. The steering is very agreeable and nice to handle, especially when the ride control is on the maximum. When in the minimum position, the steering is still quite satisfactory, but at low speeds (40 m.p.h.), over certain very bad pavé roads, one has a tendency to think that it would be possible to get into a low speed wobble, although we did not actually get this (undoubtedly Grylls will)! The ride is improved at all speeds, but more especially so at the low speeds up to 80 k.p.h. which, as you know, are the speeds at which today we get certain complaints from customers. There is decidedly less whip on the steering column and, unless I am very much mistaken, less wing movement. I do not doubt that what with their amazing road holding propensities and the added comfort, you will agree with me that these tyres have a tremendous advantage where pavé is concerned. They literally absorb the French pavés. This is so amazing as to seem unbelievable. In the Bois de St.{Capt. P. R. Strong} Cloud, where there still remains a portion of what is known as "Le Pavé du Roy{Sir Henry Royce}" and where my car, in spite of large tyres to the rear, gets itself into a proper shudder, with these tyres on, one hardly realises that there is any pavé at all. They are also quieter on pavé and quieter at speed on all surfaces than India tyres, although this is not the case with bitumed roads at speeds up to 3000 revs, when these tyres seem more noisy than our usual ones. Michelins point out to me, and wish me to lay stress on the point with your goodselves, that these wheels and tyres are what they call an experimental knock up job, as they have found it necessary to offset the rims by 22 mm. in order to clear the brake drums. The effect of carrying out the above would increase the track, the distance from the steering pivot would be increased and this could have detrimental effects on the steering on certain chassis, but they do not consider that this is the case where the Bentley is concerned, owing to the very low pressures in their tyres compared with the pressures we have generally had. I have removed the wheels from my car after this experiment and they are now ready to be shipped to you for you to pick them to pieces. Messrs. Michelins have also informed their London Depot that you might call upon them for tyres of the dimensions fitted to the wheels in question and they are sending them out some of these. | ||