Relaxation Behavior
The longitudinal deformation
and lateral deformation
For small values of u and v, the longitudinal and lateral forces will be
Where 
and 
are tire’s structural stiffness in longitudinal and lateral
direction respectively. Using relaxation lengths in force calculation will result in
following equations
Where
The force calculation remains but 
and 
is used in place of 
and 
.
When the state value goes out of bounds; an artificial damping can be applied to the state values. It is required when a tire goes over big obstacles. Low_speed_threshold, damp_x, damp_y are three additional parameters in tire property file that can be used to tune artificial damping to avoid nonphysical values of state.