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In recent years the comfort and fatigue of passengers in vehicles has become a major engineering consideration. Among the many factors involved are vibratory and auditory disturbances. Tires participate, among other elements of the vehicle, in exciting vibrations and noises. Furthermore, tires also may generate forces leading to lateral drift of the vehicle. This recommended practice describes the design requirements of equipment for evaluating some of the characteristic excitations of passenger tires causing disturbances in vehicles. The kinds of excitations treated result from nonuniformities in the structure of the tire and have their effect when a vehicle bearing the tire travels on a smooth road. This recommended practice also describes some broad aspects of the use of the equipment and lists precautionary measures that have arisen out of current experience.

This SAE Recommended Practice is applicable to pneumatic Passenger Car “P” Type, Light Truck Metric, and Light Truck High Flotation tires, or similar tires approved by bodies other than Tire & Rim Association. The methodology is applicable within normal operating ranges of vertical load and inflation pressure, and for velocities between 115 km/h and 15 km/h (71 mph and 9 mph) during a relatively short duration event such as a coastdown. This procedure is applicable only to operation in the free-rolling mode at zero slip and camber angle for ambient temperatures between 20 °C and 28 °C (68 °F and 82 °F) and for surfaces with diameters of 1.2 m (48 in) diameter or greater. Details regarding the equipment, tires, and test methods used specifically for validation of this document are included in Appendix A. Two basic measurement methods covered by this document are as follows:

This SAE Recommended Practice provides a test procedure for determining passenger car tire revolutions per mile. It is intended to supplement SAE J678.

This SAE Recommended Practice applies to the laboratory measurement of rolling resistance of pneumatic passenger car, light truck, and highway truck and bus tires. The procedure applies only to the steady-state operation of free-rolling tires at zero slip and inclination angles; it includes the following three basic methods: