The concept of the relaxation length is often used to describe a tire's transient response. This paper investigates how the transient response changes under different operating conditions. Through the measurement of tire forces and tire deformations during transient maneuvers performed on an indoor flat-belt tire test machine, experimental data were used to calculate various tire stiffnesses and the associated relaxation lengths using a novel method via optimization.
With this methodology, the effects of tire load, inflation pressure, speed, and temperature on these stiffnesses and the relaxation length have been identified. The mechanisms behind these effects are discussed with a particular focus on the influence of temperature.