Description / Abstract: Purpose. Define the process for obtaining unloaded tire fixed-free vibratory radial, lateral and torsional (alternatively, tangential) modes residing in a band of frequencies through approximately 300 Hz. Modes are measured responsive to impact excitation. These measurements are used to calculate tire local stiffnesses and modal damping. These local stiffnesses and damping, in turn, characterize tires for various global response properties influencing vehicular performance such as vibration, noise, ride, steering and handling.

Applicability. The test procedure is appropriate to use for all passenger cars, vans and small bus tire wheel systems.