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).
Comparison of mileage and performance between cord and woven fabric tyres.
| Identifier | ExFiles\Box 45\1\ Scan210 | |
| Date | 20th June 1921 | |
| contd. -2- Hs{Lord Ernest Hives - Chair}6/LG20.6.21. ----------- tread has hardly worn at all. The average mileage we have obtained with the new Dunlop cord straight-sided tyres is 4100 miles on the rear wheels. The best mileage we have obtained on the rear wheels has been 4850. The worst mileage has been 3500. With the woven fabric beaded tyres we have had some tyres which have lasted 4000 miles on the rear wheels but owing to the bursts in the fabric, the average mileage is much less than with the cord tyre. The disadvantage we have found with the cord fabric is that there is less demping in the tyre itself. The friction in the woven fabric which is the cause of it bursting has certain virtues in demping the rebound of the tyre. As, however, our tests have proved that the friction in the fabric tyres is bought very dearly, one cannot justify the woven fabric tyres on that account. Our experience has shown that although we lose a little comfort with the cord tyre owing to the absence of inherent friction, we can get it back by running the cord tyres with lower pressures. We consider it is possible to do this with cord tyres because the flexing of the fabric is not so serious. We have got the Dunlop people to agree that as long as the fabric will stand up the tyre can be run at a low pressure. The reason all tyre manufacturers demand the tyres to be pumped up hard is to relieve the flexing on the fabric. We have found on our own cars, we actually get a greater mileage with low-pressure tyres than with high-pressure. If we have hard tyres the axle contd:- | ||