Tire Longitudinal Elasticity and Effective Rolling Radii: Experimental Method and Data

To evaluate traction and velocity performance and other operational properties of a vehicle requires data on some tire parameters including the effective rolling radius in the driven mode (no torque on a wheel), the effective radii in the drive mode (torque applied to the wheel), and also the tire longitudinal elasticity. When one evaluates vehicle performance, these parameters are extremely important for linking kinematic parameters (linear velocity and tire slip coefficient) with dynamic parameters (torque and traction net force) of a tired wheel.

This paper presents an experimental method to determine the above tire parameters in laboratory facilities. The facilities include Lawrence Technological University's 4x4 vehicle dynamometer with individual control of each of the four wheels, Kistler RoaDyn^® wheel force sensors that can measure three forces and three moments on a wheel, and a modern data acquisition system.

The experimental data are also presented in the paper. It was shown that both the effective rolling radius in the driven mode and the tire longitudinal elasticity depend on the tire inflation pressure, and the effective rolling radius in the drive mode decreases when the wheel torque increases. The presented approach gives an opportunity to obtain effective rolling radii in the driven and drive modes, and also longitudinal tire elasticity from one and the same experiment without doing extra experiments for each of these parameters.