What is Relaxation length?

Relaxation length is a property of pneumatic tires that describes the delay between when a slip angle is introduced and when the cornering force reaches its steady-state value.It is also described as the distance that a tire rolls before the lateral force builds up to 63% of its steady-state value.It can be calculated as the ratio of cornering stiffness over the lateral stiffness, wherecornering stiffness is the ratio of cornering force over slip angle, andlateral stiffness is the ratio of lateral force over lateral displacement.