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The goal of this paper is to provide an automotive engineer with an explanation of the basic pitch sequencing concepts. It will also provide a historical overview of the various approaches that have been used to develop quiet tires and their progression in effectiveness. Graphs will show a Fourier analysis of the individual pitch sequences used as examples. These examples have been pulled from various US patent documents, since literature on this subject tends to be very sparse. The reduction of tire noise in the vehicle interior has been a major field of research in the tire industry for many years. Pitch sequencing for tire tread designs has been the primary method for obtaining improvements in subjective tire noise quality for about 60 years. Pitch sequencing is a method of providing frequency modulation in the tire by selectively arranging tread elements of various sizes. One of the early patents, awarded in 1950, that has been frequently quoted was by Frederick E.

It is difficult to quantify the portion of coasting vehicle noise that is due to tire-pavement interaction alone. There are often contributions from aerodynamic noise of the vehicle, transmission whine, noise from suspension components, and other miscellaneous sources. The towed-trailer method used in the revised SAE J57 standard has been shown to be an effective means of isolating tire-pavement noise for truck tires. This paper reports the results of a test program conducted by SAE Tire Noise Standards Committee to evaluate the feasibility of towed-trailer coast-by testing of passenger and light truck tires. The results of tests conducted in April 1996 at the Ohio Transportation Research Center are described and they indicate that accurate measurements are possible for towed-trailer testing of passenger tires. It is shown that a key aspect of performing such a test is reducing the noise of the tow vehicle and that sufficient reduction is possible even for extremely quiet test tires.

The possibility of using a trailer to measure pass-by sound levels of tires has been limited by the tire noise generated by the tow vehicle. In order to verify the viability of the trailer method for passenger car tires, a trailer and tow vehicle were constructed and tested. A reduction goal of 3 dB(A) below the tow vehicle and trailer with the test tire was required for the tow vehicle alone. The noise reduction treatment, designed and developed for this project, successfully reduced the tow vehicle sound level enough to permit the coast-by trailer method to be used for tires as small as P145/80R13.