Normal Force of Tire

The normal force of a road on a tire at the contact patch is generated the direction of z-axial in the contact coordinates.

                    (1)

where,:

 is the normal force due to tire vertical stiffness.

 is the normal force due to tire vertical damping.

, and

 : Vertical tire stiffness

 : Penetration (tire deflection)

 : Mass of tire

 : Vertical damping ratio

Figure 1  Step function

 is the step function of penetration.

 is the carcass radius of toroidal tire.