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).
Performance, costs, and issues related to straight-sided cord tyres versus canvas tyres.
| Identifier | ExFiles\Box 49\3\ Scan050 | |
| Date | 22th June 1921 | |
| To CJ. From R.{Sir Henry Royce} c. to SA. c. to EAG. c. to Hs.{Lord Ernest Hives - Chair} c. to R.R.Inc. for attention of OY. X4261 RIO/G22.6.21. X.4050 - RE STRAIGHT-SIDED CORD TYRES. X.4261 X.4262 Regarding post-war complaints about cars, it seems now universal to use the corded construction for tyres. Mr. Hives has given us his report that these are much more satisfactory than canvas tyres, there being no bursts and the tyres lasting for an average of 4,000 miles on the rear wheels and probably 8,000 miles on the front wheels. This would seem to work out at about 1½d.{John DeLooze - Company Secretary} per mile for tyres, and as the petrol is now costing 3/- per gallon, and one can do 15 miles to the gallon, the cost of petrol and oil should not exceed 2½d.{John DeLooze - Company Secretary} and therefore the cost of this item ought not to be more than 4d. per mile. There are very many other items which are serious, such as tax, insurance, interest, depreciation and repairs. All of these items should be very materially decreased with the 20 H.P., but there will also be a decrease in comfort and speed. It would be noticed from Mr. Hives conclusions that definitely a large amount of the complaints against the running of cars on bumpy roads in America is due to the less damping of the cord tyres, also to the fact that free air is available at all the garages, so that the tyres are probably always in a state of being very tightly inflated. It will be understood that our chassis is so substantially built about the back axle that it is naturally rather heavier contd. | ||