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).
Paper discussing the various factors that cause variation in tire wear, such as speed and temperature.
| Identifier | ExFiles\Box 45\2\ Scan074 | |
| Date | 4th June 1928 guessed | |
| Left Page (decoded from mirrored text): Copy of Pamphlet Issued by The Rubber Association of America, Inc. for Reasons for Variation in Tire Wear Right Page: The Reasons for Variation in Tire Wear. THE present era of improved roads, increased automobile activity, and intensive automobile performance has brought on new operating conditions which cause a wide variation in the amount of wear that is possible from tires of the same make or the same quality. The Rubber Association of America, Inc., has recognised this growing problem and its attendant misunderstandings, and has, therefore, gathered data from all member companies, assembled it, and, for general education of the industry, drawn it up in this paper. In this study there are a great number of major factors, each of which covers a lot of smaller ones: some interlock with others, yet each has its distinctive effect on the performance. These factors are as follows:— 1. SPEED.—High-speed driving is a natural thing to-day. Cars are capable of higher speeds than before—roads permit it, and even the Balloon tire itself, with its extra cushioning quality, makes sustained high speed over rough roads possible. People have become accustomed to driving to such an extent that the average speed on the open road is at least 10 to 15 miles higher than it was three years ago. Compare this with the fact that tires which wear 12,000 miles at 35 miles per hour will give only 6,000 miles at 45 miles per hour under the same road conditions and temperature. An increase of 10 miles per hour in speed doubles the rate of wear between 30 and 50 miles per hour. Below 30 miles per hour the increase is lower, but above 50 miles per hour the rate of wear increases very rapidly. The following table indicates the increase in wear due to speed at various temperatures: Temperature. 20 M.P.H. 30 M.P.H. 40 M.P.H. 40 degrees 100% 108% 150% 60 degrees 191% 217% 275% 80 degrees 317% 367% 450% 100 degrees 491% 558% 717% There is probably no one factor that is causing such a wide range in tire wear as speed, because there is such a wide range in the amount of speed engaged in. On the Indianapolis Speedway, specially built racing tires hardly last 500 miles. The car owner of to-day may use his car for many months without giving it much hard usage, then suddenly he will take a short vacation trip during which he unconsciously drives at a very high rate of speed on an average, and in a comparatively short mileage will wear away sufficient tread rubber to cut his mileage in half. | ||