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.
| Identifier | ExFiles\Box 157\1\ scan0232 | |
| Date | 30th October 1935 | |
| -3- Hs{Lord Ernest Hives - Chair}/Wym.{G. Harold Whyman - Experimental Manager}23/KW.30.10.35. 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. | ||