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).
Effects of low-pressure tyres on vehicle performance characteristics.
| Identifier | ExFiles\Box 53\2\ Scan043 | |
| Date | 21th August 1923 guessed | |
| 6. In effect also this tyre when in deflated condition becomes a cushion tyre and provides a "soft" bed which prevents casing or tube destruction - whereas normal tyres tend to chafe the tube and disintegrate the cover when run deflated. 19. EFFECT ON ACCELERATION. Reduced wheel diameter means more rapid acceleration and also greater range of brake control before wheels become locked, by reason of the fact of the lighter periphery used for wheel. 20. EFFECT ON SPEED. First experience on Low Pressure Tyres gives the impression of reduced speed, apparently due to the greatly reduced vibration and silence on a used car. Repeated tests on large and medium powered cars on Brooklands track under identical conditions prove definitely that there is no difference in speed when using normal as compared with low Pressure Tyres. This Track is favourable to normal tyres due to its comparative smoothness. The Low Pressure Tyre shews up to the best advantage on a rough road,- a road with pot holes being classed as rough roads. Such roads constitute to a greater or less degree average conditions and beyond question the Low Pressure Tyre makes for a higher "comfortable" or "natural speed" without the passenger or driver being conscious of such higher average. 21. EFFECT ON PETROL CONSUMPTION. Repeated tests on medium power cars on both road and track have always shewn a substantial economy due to the use of the low pressure tyre - this being on the road 5% to 10% economy, but on the track as much as 30% - this test requires confirmation. On a large power car - the track tests up to date shewed an economy of some 4% to 5% in favour of the normal tyre. This test also requires confirmation. 22. EFFECT ON ENGINE TORQUE. The increased tyre section combined with flexible tyre wall and Low pressures provide an appreciable cushioning effect on the engine - Table No..... shews on two different cars that with normal tyres | ||