Factors Influencing the Measurement of Tire Uniformity 650734
Tire nonuniformities are a major source of vibration problems in vehicles. There is considerable disagreement on which tire uniformity parameters are important to vehicle noise and vibration problems, and on how these uniformity parameters should be measured. This paper is concerned primarily with the effects of the nonuniformities of the tire structure which cause contact patch force variations as the tire is rolled in a straight line at constant axle height.
Experimental results showing the effects of mean radial load and roll size on these structural, or static, nonuniformities are presented which indicate that these force variations should be measured on a large roll at rated load. Mathematical analyses of certain vehicle vibrations show that radial and lateral force variation are important uniformity parameters. The amplitude of the first harmonic of these force variations contributes to vehicle shake. Specifications for tire uniformity grading machines are presented together with suggestions for machine instrumentation.