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).
Summary of test results showing factors affecting tyre noise with comparative noise percentages.
| Identifier | ExFiles\Box 30\5\ Scan150 | |
| Date | 7th October 1935 guessed | |
| -3- Summarised, the position as far as our tests have gone at the moment is as follows :- Tyre noise is affected by the following :- Percentage of Noise (Comparative) (1) Different types of Chassis Cadillac: Nil. Graham: 5% 25 HP.RR.: 10% Ph.II.RR.: 25% Ph.III.RR.: 40% (2) Different Coachwork on same Chassis. 30-EX: 20% 33-EX: 25% 34-EX: 50% (3) Difference in Tyre Patterns. Avon Supreme: 10% Goodrich (B.T.R.): 20% Dunlop Original '90' Type: 20% Dunlop Silent: 35% Dunlop Present '90' Type: 40% India Super: 40% India Super after 3,000 miles.: 60% (4) Difference in Load and Inflation Pressures. Greater the load - greater the noise Lower the pressures - greater the noise. (5) Difference in Road Surfaces. | ||