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).
Tyre pressures for cars of varying weights, and a recommendation to standardise straight-sided cord construction tyres, listing their advantages.
| Identifier | ExFiles\Box 45\1\ Scan211 | |
| Date | 20th June 1921 | |
| contd. -3- Hs{Lord Ernest Hives - Chair}6/LG20.6.21. dances about on the road, the wheels are flung clear and when they come in contact the tread is scrubbed off. On cars weighing 40 to 45 cwts. we have run with 55 lbs. pressure alroun On cars weighing 45 to 55 cwts. we have run with 60 lbs. press- ure. On cars weighing above 55 cwts. we run with 65 lbs. pressure.* With these pressures we have never had a case of the tyre bursting until the tread has worn away, so that we consider the pressures legitimate. We have never experienced the least trouble on any straight-sided tyres due to the absence of the bead. From the results of our tests we recommend that we standardise the straight-sided cord construction tyres. The advantage we have found in these tyres over those we are using at present are as follows:- 1. Greater mileage from the tyres. 2. Freedom from bursts. 3. The effort required to change a tyre is very considerably reduced. 4. There is no need for security bolts. 5. Tyres can be run with a lower pressure Another claim is that the cord tyre is more efficient; this is a reasonable claim. We have proved that a car will "free-wheel" further on cord tyres than on fabric but we have not been able to measure the difference in consumption when using the same pressures. The cord tyre should, however, give better efficiency. Hs.{Lord Ernest Hives - Chair} | ||