Tire Physical Data Dialog¶

The tire physical parameters for the selected wheel position are displayed and edited using the Tire Physical Data dialog (title: Tire Physical Data: <Mfr> <Model> <Size>). Each parameter may be set with a slider or typed directly into its edit field.

This dialog contains the following items (in dialog order):

Unloaded Radius¶

Undeflected tire radius (no-load condition).

Maximum Width¶

Maximum section width of the tire. This value is display-only; it is computed from the tire size designation string. (New since the original help.)

Tread Width¶

Width of the tire tread contact patch. (New since the original help.)

Tread Depth¶

Depth of the tire tread. (New since the original help.)

Nominal Pressure¶

Nominal (rated) inflation pressure of the tire. (New since the original help.)

Initial Deflection Rate¶

The initial tire spring rate (vertical tire load per unit of linear tire deflection).

Secondary Deflection Rate¶

The spring rate under conditions of excessive tire vertical load.

Deflection at Secondary Rate¶

Tire deflection at which the secondary deflection rate begins.

Maximum Deflection¶

Tire maximum deflection. This value is normally used to terminate execution, indicating the probability of a damaged or broken wheel rim.

Pneumatic Trail¶

Longitudinal distance from the center of the tire contact patch to the center of pressure. Pneumatic trail increases the self-aligning tendency of a steerable wheel.

Aligning Torque Coef¶

Self-aligning torque coefficient due to mechanical and pneumatic trail.

Weight¶

Total weight of the wheel assembly (tire plus rim). For an independent suspension, the value reflects the total unsprung mass. For a solid axle suspension system, the axle weight is added to the wheel weight to determine unsprung mass. The displayed weight is calculated from the stored tire mass.

Spin Inertia¶

Tire rotational inertia about its spin axis.

Steer Inertia¶

Tire rotational inertia about its steering axis.

Rolling Resist Const¶

Tire rolling resistance constant force coefficient.

Rolling Resist Linear¶

Tire rolling resistance linear, velocity-dependent force coefficient.

Min Fz For Skidmark¶

Minimum vertical tire force required in order to cause a visible tire mark on the road.

OK / Cancel¶

OK validates each entry against its allowed range and stores the physical data for the tire. Cancel discards all changes.

Source topic: TirePhyDataDlg.htm — updated from source code (HVEINV-64, Physics) 2026-07-05.

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