Chapter 11 — Vehicle Model Definition (Part D: Brakes, Tires and Wheels)¶

This part covers the unsprung-mass properties edited by clicking on a wheel in the Vehicle Viewer: the Brake Assembly at each wheel, the Tire properties, the Wheel Location and the Wheel Image.

Brake Assembly Parameters¶

The Brake Assembly properties for the selected wheel are displayed and edited using the Brake Assembly dialog. See also the code-verified reference page, Brake Assembly dialog.

Figure 11-36: Brake Assembly dialog for editing the properties of the brake system at the selected wheel.

To display or edit the current vehicle's brake assembly parameters at a selected wheel, perform the following steps:

In the Vehicle Viewer, click on the desired wheel. The Unsprung Mass options for the selected wheel are displayed.
Choose Brake from the Unsprung Mass option list. The Brake Assembly dialog for the selected wheel is displayed.
View and/or edit the desired properties.
Press OK to accept the changes.

Figure 11-37: Brake System Proportioning.

Figure 11-38: Simple Antilock Model.

The Brake properties at each wheel are described below.

Time Lag — Time required before the driver's brake pedal inputs reach the wheel.
Time Rise — Time required for the brake pressure at the wheel brake actuator to reach approximately 90 percent of full system pressure (pressure in the air chamber rises at an exponential rate).

NOTE: If a simulation model does not use HVE's Time Lag or Time Rise parameters, the lag and rise time may be simulated in the Brake Table (see Event Editor, Driver Controls).

Brake Type — An option list displaying the type of brake assembly used at the selected wheel location. The default is Generic; in this case, the Brake Torque Ratio (see below) is defined directly by the user. The other types are Disc, Duo-Servo, Duplex, Single Piston, Dual Piston, S-Cam, Single Wedge, Dual Wedge and Air Disc (updated: Air Disc was added since the legacy manual).

NOTE: See the HVE Brake Designer documentation for details on the use of this option. When a specific (non-Generic) brake design is selected, the Edit Brake... button opens the Brake Designer dialog for that assembly type, and the Push-out Pressure and Brake Torque Ratio are computed by the Brake Designer. (updated: selecting Disc or Air Disc also sets the wheel brake assembly type for the axle to Disc, while the drum-based designs set it to Drum.)

Push-out Pressure — Brake system pressure required to begin causing brake torque (any system pressure below this point is simply taking out the slack in the system).
Brake Torque Ratio — Wheel brake torque per unit of system pressure at the wheel. The actual braking torque at the wheel is the product of the current wheel system pressure and the Brake Torque Ratio.
Proportioning Check Box — Click on this check box if the system pressure at the selected wheel is reduced by a proportioning valve.
Proportioning Starting Pressure — Beginning at this level of system pressure, any additional master cylinder pressure will be reduced (see Figure 11-37).
Proportioning Ratio — At master cylinder pressures above the Proportioning Starting Pressure, additional pressure is reduced by this ratio (see Figure 11-37).
Anti-lock Check Box — Click on this check box if the selected wheel has a simple (functional) anti-lock device installed.
Anti-lock Efficiency — A 100% effective anti-lock system maintains a longitudinal wheel force associated with the peak coefficient of friction. A 0% effective system maintains a longitudinal wheel force associated with the slide coefficient of friction. A 50% effective system would maintain a longitudinal force halfway between that associated with peak and slide friction (see Figure 11-38).
ABS Designer — A pushbutton used to access the ABS Wheel Data dialog of the HVE Brake Designer (updated: the ABS Designer edits detailed ABS wheel data — wheel kinematics thresholds such as minimum velocity, tire slip range and spin acceleration range, and pressure modulation parameters such as cycle rate, apply/release delays and apply/release rates).

NOTE: The Simple Antilock option is not enabled if the vehicle is fitted with an ABS brake system. The ABS Designer pushbutton is not enabled if the brake system is not fitted with ABS (ABS is installed in the Brake System Pressure vs Pedal Force dialog). See Brake System Parameters in Part E.

Table 11-19: Wheel Brake Assembly Parameters

Parameter	Unit Name	Description
Time Lag	UtBraTime	Time required for brake system pressure to reach the wheel
Time Rise	UtBraTime	Time required for the brake pressure at the wheel brake actuator to reach approximately 90 percent of full system pressure
Push-out Pressure	UtBraPress	Pressure required to begin braking
Brake Torque Ratio	UtBraRatio	Brake torque per unit of system pressure at the wheel
Proportioning	boolean (TRUE or FALSE)	Flag; if TRUE the wheel pressure is reduced by a proportioning valve
Pstart	UtBraPress	Brake system pressure at which proportioning begins for the selected wheel location
Proportioning Ratio	UtNone	Ratio of pressure at the wheel to pressure at the master cylinder
Antilock	boolean (TRUE or FALSE)	Flag; TRUE if the wheel has an antilock device
Anti-lock Efficiency	UtBraPercent	Efficiency of the antilock system at the selected wheel

HVE Brake Designer¶

The HVE Brake Designer provides a detailed brake design capability integrated directly within the HVE simulation environment. This feature allows vehicle designers and safety researchers to develop a specific brake design for each wheel and evaluate the resulting vehicle performance using a predefined suite of maneuvers or compliance test simulations. The HVE Brake Designer also includes a detailed tool for simulating ABS.

The Brake Designer dialogs for the individual assembly types are documented in the code-verified reference pages: Disc Brake, Duo-Servo, Duplex, Single Piston, Dual Piston, Dual Wedge and Brake Material Properties.

Tire Properties¶

The tire parameters for the current vehicle are displayed and edited using the Tire Information dialog. See also the code-verified reference page, Tire Information dialog.

Figure 11-39: The Tire Information dialog is used for selecting and editing tires, as well as for maintaining the Tire Database.

The Tire Information dialog includes a user-extendible database that allows the user to create and edit tires according to the following database keys:

Tire Type
Tire Manufacturer
Tire Model
Tire Size
Source Database

To display and possibly change the current tire at a selected wheel, perform the following steps:

In the Vehicle Viewer, click on the desired wheel. The Unsprung Mass options for the selected wheel are displayed.
Choose Tire from the Unsprung Mass option list. The Tire Information dialog for the selected wheel is displayed, showing the current tire's Name, Type, Manufacturer, Model and Size Designation.
If desired, change the tire's Name, Type, Manufacturer, Model and/or Size Designation by entering a new name or clicking on the appropriate option list and choosing a new option.

NOTE: The Name is simply a user-editable field available for describing the tire. For example, you may choose a tire from the database and greatly reduce its cornering and camber stiffness to simulate a flat tire. In that case, you might enter the name as "Flat Generic Tire" to indicate its properties have been changed.

Press OK to accept the changes.

For the selected tire, the Tire Information dialog also allows the user to edit the following specific tire properties:

Physical Properties
Frictional Properties
Cornering Stiffness Table (Fy vs Slip Angle)
Camber Stiffness Table (Fy vs Inclination Angle)
Slip vs Rolloff Tables

Each of these is described in the following sections.

NOTE: For information about adding new tires to the Tire database, refer to Chapter 2 (see Creating Databases) and Appendix VIII (User Databases).

NOTE: Contact EDC to obtain an interesting video that shows how these tire properties are determined from tests on Calspan's Flatbed Tire Testing machine. Ask for EDC Library Ref. No. 1077.

Tire Physical Data¶

The Tire Physical parameters for the selected wheel position are displayed and edited using the Tire Physical Data dialog. See also the code-verified reference page, Tire Physical Data dialog.

Figure 11-40: The Tire Physical Data dialog is used for editing the tire's physical parameters.

To display or edit the current vehicle's physical tire properties at a selected wheel, perform the following steps:

In the Vehicle Viewer, click on the desired wheel. The Unsprung Mass options for the selected wheel are displayed.
Choose Tire from the Unsprung Mass option list. The Tire Information dialog for the selected wheel is displayed.
If desired, change the tire by selecting a different Tire Type, Manufacturer, Model and/or Size.
Choose Physical Data. The Tire Physical Data dialog for the selected tire is displayed.
View and/or edit the desired properties.
Press OK to accept the changes. The Tire Information dialog is still displayed.
If desired, click Copy To Other Side to make the changes apply to both sides.
Press OK to accept the tire physical changes to the selected wheel position.

The Tire Physical Data parameters are described below.

Unloaded Radius — Undeflected tire radius (no-load condition).
Maximum Width — (updated: added in Version 7 tire data.) Maximum section width of the tire. This value is display-only; it is computed from the tire size designation string.
Tread Width — (updated: added in Version 7 tire data.) Width of the tire tread contact patch.
Tread Depth — (updated: added in Version 7 tire data.) Depth of the tire tread.
Nominal Pressure — (updated: added in Version 7 tire data.) Nominal (rated) inflation pressure of the tire.
Initial Deflection Rate — The initial tire spring rate (vertical tire load per unit of linear tire deflection). See Figure 11-41.
Secondary Deflection Rate — The spring rate under conditions of excessive tire vertical load. See Figure 11-41.
Deflection At Secondary Rate — Tire deflection at which the secondary deflection rate begins. See Figure 11-41.
Maximum Deflection — Tire maximum deflection. This value is normally used to terminate execution, indicating the probability of a damaged or broken wheel rim. See Figure 11-41.
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 (negative if the center of pressure is behind the center of contact).
Aligning Torque Stiffness — Self-aligning torque due to mechanical and pneumatic trail.
Weight — Total weight of the wheel assembly (tire plus rim). For an independent suspension, this 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.

NOTE: The entered value is divided by the current gravitational constant and stored as mass. That way, if you take the vehicle to the moon, it will behave correctly!

Spin Inertia — Tire rotational inertia about its spin axis.
Steer Inertia — Tire rotational inertia about its steering axis.
Rolling Resistance Constant — Tire rolling resistance force coefficient.
Rolling Resistance Linear Coefficient — Tire rolling resistance linear, velocity-dependent force coefficient.
Minimum Fz For Skid — Minimum vertical tire load, Fz, required in order to leave a tire mark on the road surface. If the current vertical tire load is less than this value, no tire mark is displayed.

Figure 11-41: Tire Physical Parameters.

Table 11-20: Tire Physical Data Parameters

Parameter	Unit Name	Description
Unloaded Radius	UtTirDispLength	Tire radius in unloaded condition
Maximum Width	UtTirDispLength	Maximum section width (computed from size designation) (updated: Version 7)
Tread Width	UtTirDispLength	Width of the tread contact patch (updated: Version 7)
Tread Depth	UtTirDispLength	Depth of the tire tread (updated: Version 7)
Nominal Pressure	UtTirPress	Nominal inflation pressure (updated: Version 7)
Initial Deflection Rate	UtTirRateLinear	Deflection rate from zero deflection to secondary deflection
Secondary Deflection Rate	UtTirRateLinear	Deflection rate after preliminary deflection
Deflection At Secondary Rate	UtTirDispLength	Deflection at start of secondary deflection rate
Maximum Deflection	UtTirDispLength	Maximum allowable tire deflection
Pneumatic Trail	UtTirDispLength	Distance from center of the contact patch to the center of pressure
Aligning Torque Stiffness	UtTirAlignTorque	Steering torque produced by tire slip angle
Weight	UtTirForce	Total weight of wheel (tire + rim)
Spin Inertia	UtTirInertia	Rotational inertia about spin axis
Steering Inertia	UtTirInertia	Rotational inertia about steering axis
Rolling Constant	UtNone	Ratio of rolling resistance force to total vertical force on tire
Rolling Linear Coef	UtTireVelDependence	Velocity-dependent tire rolling resistance force coefficient
Min Fz for Skidmark	UtTirForce	Minimum vertical tire force required for a tire to leave a skidmark

Tire Friction Data¶

The tire frictional properties for the selected wheel position are displayed and edited using the Tire Friction Data dialog. See also the code-verified reference page, Tire Friction Data dialog.

Figure 11-42: The Tire Friction Data dialog is used for editing the tire's frictional properties.

To display or edit the current vehicle's tire frictional properties at a selected wheel, perform the following steps:

In the Vehicle Viewer, click on the desired wheel. The Unsprung Mass options for the selected wheel are displayed.
Choose Tire from the Unsprung Mass option list. The Tire Information dialog for the selected wheel is displayed.
If desired, change the tire by selecting a different Tire Type, Manufacturer, Model and Size.
Click on Friction Data. The Tire Friction Data dialog for the selected tire is displayed.
Click on the Load combo box to view and/or edit the list of vertical loads (up to 3 loads may be supplied).
Click on the Speed combo box to view and/or edit the list of test speeds (up to 3 speeds may be supplied).
At the selected load and speed, view and/or edit the frictional properties and longitudinal stiffness of the tire.
Select an In-use Factor for the tire. The In-use Factor acts as a modifier that multiplies the current dependent tire data.

NOTE: For example, let's say you believe a given tire's frictional properties are only 90 percent of the values displayed in the dialog. You could calculate 90 percent of the peak and slide friction and longitudinal stiffness values and edit the current data accordingly, or you could simply choose an in-use factor of 0.90.

Press Apply to update the graph of Fx/Fz vs Longitudinal Slip.
Press Print to print the graph on the system printer. Press OK to accept the changes. The Tire Information dialog is still displayed.
If desired, click Copy To Other Side to make the changes apply to both sides.
Press OK to accept the tire friction data changes to the selected wheel position.

The Tire Friction Data parameters are described below.

Load — Vertical tire load at which the frictional values were obtained.
Speed — Road speed at which the frictional values were obtained.
Peak Longitudinal Friction — Maximum value of Fx/Fz achieved during the test at the given load and speed.
Peak Lateral Friction — Maximum value of Fy/Fz achieved during the test at the given load and speed.
Slide Friction — Value of Fx/Fz at 100% longitudinal slip achieved during the test at the given load and speed.
Slip at Peak Friction — Longitudinal slip at which the peak longitudinal friction was achieved at the given load and speed.
Longitudinal Stiffness — Slope of the Friction vs Slip curve (see Figure 11-42) at the graph's origin.

NOTE: The graph uses the longitudinal stiffness to display the curve up to 0.5 times the Peak Longitudinal Friction.

In-use Factor — Global multiplier for dependent values (Peak and Slide Friction, Longitudinal Stiffness).

Table 11-21: Tire Friction Parameters

Parameter	Unit Name	Description
Load	UtTirForce	Vertical tire load, Fz, during test
Speed	UtTirVelLinear	Speed during test
Peak Longitudinal Friction	UtNone	Maximum value of Fx/Fz achieved at given load and speed
Peak Lateral Friction	UtNone	Maximum value of Fy/Fz achieved at given load and speed
Slide Friction	UtNone	Value of Fx/Fz achieved at 100% slip
Slip at Peak Long. Friction	UtTirPercent	Longitudinal slip at which Peak Longitudinal Friction was measured
Longitudinal Stiffness	UtTirLongStiff	Slope of Friction vs Slip graph at zero slip
In-use Factor	UtTirPercent	Multiplier for Peak and Slide Friction and Longitudinal Stiffness

Tire Fy vs Slip Angle Table¶

The Tire Fy vs Slip Angle Data (Cornering Stiffness) for the selected wheel position are displayed and edited using the Tire Fy vs Slip Angle Data dialog.

Figure 11-43: The Tire Fy vs Slip Angle Data dialog is used for editing the selected tire's lateral force producing properties.

To display or edit the current vehicle's cornering parameters at a selected wheel, perform the following steps:

In the Vehicle Viewer, click on the desired wheel. The Unsprung Mass options for the selected wheel are displayed.
Choose Tire from the Unsprung Mass option list. The Tire Information dialog for the selected wheel is displayed.
If desired, change the tire by selecting a different Tire Type, Manufacturer, Model and Size.
Choose Fy vs Slip Angle Table. The Fy vs Slip Angle Table dialog will be displayed.
Click on the Load combo box to view and/or edit the list of vertical loads (up to 3 loads may be supplied).
Click on the Speed combo box to view and/or edit the list of test speeds (up to 3 speeds may be supplied).
At the selected load and speed, view and/or edit the Fy vs Slip Angle Table using the scrollable listbox.
At the selected load and speed, view and/or edit the cornering stiffness of the tire.

NOTE: The cornering stiffness defines the slope of the Fy vs Slip Angle curve at zero slip angle.

Select an In-use Factor for the tire. The In-use Factor acts as a modifier that multiplies the current dependent tire data.

NOTE: For example, let's say you believe a given tire is partially deflated, resulting in a 50 percent reduction in cornering stiffness characteristics. You could calculate 50 percent of each Fy and Cornering Stiffness value, then edit the Fy vs Slip Angle Table and Cornering Stiffness. Alternatively, you could achieve the same result by simply choosing an in-use factor of 0.50.

Press Apply to update the graph of Fy vs Slip Angle.
Press Print to print the graph on the system printer.
Press OK to accept the changes. The Tire Information dialog is still displayed.
If desired, click Copy To Other Side to make the changes apply to both sides.
Press OK to accept the tire cornering stiffness parameter changes to the selected wheel position.

The Tire Fy vs Slip Angle Data parameters are described below.

Load — Vertical tire load at which the cornering stiffness values were obtained.
Speed — Road speed at which the cornering stiffness values were obtained.
Slip Angle — Angle (relative to the tire axis system; see Appendix III) from the tire's forward axis to its local velocity vector.
Fy — Lateral tire force (relative to the tire axis system) produced at the current slip angle for the given load and speed.
Cornering Stiffness — Slope of the Fy vs Slip Angle curve (see Figure 11-43) at the graph's origin.

NOTE: The graph uses the cornering stiffness to display the curve up to 0.5 times the first Slip Angle entry in the table.

In-use Factor — Global multiplier for dependent values (Fy and Cornering Stiffness).

Table 11-22: Tire Fy vs Slip Angle Parameters

Parameter	Unit Name	Description
Load	UtTirForce	Vertical tire load, Fz, during test
Speed	UtTirVelLinear	Speed during test
Slip Angle	UtTirDispAngle	Angle (relative to the tire axis system; see Appendix III) from the tire's forward axis to its local velocity vector
Fy	UtTirForce	Lateral tire force (relative to the tire axis system) produced at the current slip angle for the given load and speed
Cornering Stiffness	UtTirCalfa	Slope of Fy vs Slip Angle graph at zero slip angle
In-use Factor	UtTirPercent	Multiplier for Fy and Cornering Stiffness

Tire Fy vs Inclination Angle Table¶

The Tire Fy vs Inclination Angle Data (sometimes referred to as Camber Stiffness) for the selected wheel position are displayed and edited using the Tire Fy vs Inclination Angle Data dialog. See also the code-verified reference page, Fy vs Inclination Angle dialog.

Figure 11-44: The Tire Fy vs Camber Angle dialog is used for editing the tire's camber stiffness properties.

NOTE: As a rough estimate, camber stiffness is normally about 1/10 of the cornering stiffness.

To display or edit the current vehicle's Fy vs Camber Angle parameters at a selected wheel, perform the following steps:

In the Vehicle Viewer, click on the desired wheel. The Unsprung Mass options for the selected wheel are displayed.
Choose Tire from the Unsprung Mass option list. The Tire Information dialog for the selected wheel is displayed.
If desired, change the tire by selecting a different Tire Type, Manufacturer, Model and Size.
Choose Fy vs Camber Angle Table. The Fy vs Camber Angle dialog will be displayed.
Click on the Load combo box to view and/or edit the list of vertical loads (up to 3 loads may be supplied).
Click on the Speed combo box to view and/or edit the list of test speeds (up to 3 speeds may be supplied).
At the selected load and speed, view and/or edit the Fy vs Camber Angle Table using the scrollable listbox.
At the selected load and speed, view and/or edit the camber stiffness of the tire.

NOTE: The camber stiffness defines the slope of the Fy vs Inclination Angle curve at zero inclination angle.

Select an In-use Factor for the tire. The In-use Factor acts as a modifier that multiplies the current dependent tire data.

NOTE: For example, let's say you believe a given tire is partially deflated, resulting in a 50 percent reduction in camber stiffness characteristics. You could calculate 50 percent of each Fy and Inclination Angle value, then edit the Fy vs Inclination Angle Table and Camber Stiffness. Alternatively, you could achieve the same result by simply choosing an in-use factor of 0.50.

Press Apply to update the graph of Fy vs Camber Angle.
Press Print to print the graph on the system printer.
Press OK to accept the changes. The Tire Information dialog is still displayed.
If desired, click Copy To Other Side to make the changes apply to both sides.
Press OK to accept the tire parameter changes for the selected wheel position.

The Tire Fy vs Inclination Angle Data parameters are described below.

Load — Vertical tire load at which the camber stiffness values were obtained.
Speed — Road speed at which the camber stiffness values were obtained.
Inclination Angle — Angle (relative to the tire axis system; see Appendix III) from the vertical axis of the tire plane to a vector normal to the road plane.
Fy — Lateral tire force (relative to the tire axis system) produced at the current camber angle for the given load and speed.
Camber Stiffness — Slope of the Fy vs Inclination Angle curve (see Figure 11-44) at the graph's origin.

NOTE: The graph uses the camber stiffness to display the curve up to 0.5 times the first Inclination Angle entry in the table.

In-use Factor — Global multiplier for dependent values (Fy and Camber Stiffness).

Table 11-23: Tire Fy vs Inclination Angle Parameters

Parameter	Unit Name	Description
Load	UtTirForce	Vertical tire load, Fz, during test
Speed	UtTirVelLinear	Speed during test
Inclination Angle	UtTirDispAngle	Angle (relative to the tire axis system; see Appendix III) from the vertical axis of the tire plane to a vector normal to the road plane
Fy	UtTirForce	Lateral tire force (relative to the tire axis system) produced at the current inclination angle for the given load and speed
Camber Stiffness	UtTirCgamma	Slope of Fy vs Inclination Angle graph at zero inclination angle
In-use Factor	UtTirPercent	Multiplier for Fy and Camber Stiffness

Tire Slip vs Rolloff Tables¶

The Tire Longitudinal and Lateral Slip vs Rolloff Data Tables for the selected wheel position are displayed and edited using the Tire Slip vs Rolloff Tables dialog. See also the code-verified reference page, Slip vs Rolloff dialog.

Figure 11-45: The Tire Longitudinal and Lateral Slip vs Rolloff Tables dialog is used for editing the tire's slip vs rolloff properties.

To display or edit the current vehicle's Slip vs Rolloff parameters at a selected wheel, perform the following steps:

In the Vehicle Viewer, click on the desired wheel. The Unsprung Mass options for the selected wheel are displayed.
Choose Tire from the Unsprung Mass option list. The Tire Information dialog for the selected wheel is displayed.
If desired, change the tire by selecting a different Tire Type, Manufacturer, Model and Size.
Choose Slip vs Rolloff Table. The Slip vs Rolloff Table dialog will be displayed.
Click on the Longitudinal Slip combo box to view and/or edit the list of longitudinal slips (up to 6 slip values may be supplied).
Click on the Slip Angle combo box to view and/or edit the list of lateral slip angles (up to 6 slip angles may be supplied).
At the selected longitudinal and lateral slips, view and/or edit the Longitudinal and Lateral Rolloffs.
Press Apply to update the graphs of Rolloff vs Slip.
Press Print to print the graph on the system printer.
Press OK to accept the changes. The Tire Information dialog is still displayed.
If desired, click Copy To Other Side to make the changes apply to both sides.
Press OK to accept the tire slip vs rolloff parameter changes to the selected wheel position.

The Tire Slip vs Rolloff Data parameters are described below.

Longitudinal Slip — Longitudinal tire slip at which the lateral roll-off values were obtained.
Slip Angle — Lateral tire slip (slip angle) at which the longitudinal roll-off values were obtained.
Longitudinal Rolloff — Reduction in lateral tire force (relative to the tire axis system; see Appendix III) at the specified longitudinal slip.
Lateral Rolloff — Reduction in longitudinal tire force (relative to the tire axis system) at the specified lateral slip (slip angle).

Table 11-24: Tire Slip vs Rolloff Parameters

Parameter	Unit Name	Description
Longitudinal Slip	UtTirPercent	Longitudinal tire slip at which the lateral roll-off values were obtained
Slip Angle	UtTirDispAngle	Lateral tire slip (slip angle) at which the longitudinal roll-off values were obtained
Longitudinal Rolloff	UtTirPercent	Reduction in lateral tire force (relative to the tire axis system; see Appendix III) at the specified longitudinal slip
Lateral Rolloff	UtTirPercent	Reduction in longitudinal tire force (relative to the tire axis system) at the specified lateral slip (slip angle)

Wheel Location¶

The wheel location coordinates relative to the vehicle-fixed coordinate system are displayed and edited using the Wheel Location dialog. See also the code-verified reference page, Wheel Location dialog.

Figure 11-46: The Wheel Location dialog allows the user to view and edit the wheel's x,y,z vehicle-fixed coordinates.

To display and possibly change the wheel location coordinates, perform the following steps:

In the Vehicle Viewer, click on the desired wheel. The Unsprung Mass options for the selected wheel are displayed.
Choose Location from the Unsprung Mass option list. The Wheel Location dialog for the selected wheel is displayed, showing the current wheel's x,y,z vehicle-fixed coordinates.
View and/or edit the wheel's x,y,z coordinates.
Click Copy To Other Side if you wish to apply the edits to the other side's wheel location, making the vehicle bilaterally symmetrical.

NOTE: The resulting x- and z-coordinates for the copied wheel will be the same; the y-coordinates will have the same magnitude but the opposite sign.

Press OK to accept the changes to the wheel location data.

NOTE: If you wish to move the CG, you can edit each individual wheel's x,y,z coordinates. However, an alternative (and easier) way is to use the Move CG dialog (see Sprung Mass Parameters in Part A).

Figure 11-47: Wheel locations relative to the vehicle-fixed coordinate system.

The Wheel Location parameters are described below (see Figure 11-47).

Wheel x — The longitudinal distance from the vehicle CG to the selected wheel.
Wheel y — The lateral distance from the vehicle CG to the selected wheel.
Wheel z — The vertical distance from the vehicle CG to the selected wheel.

Table 11-25: Wheel x,y,z Location Parameters

Parameter	Unit Name	Description
x, y, z coordinates	UtVehDispLength	Vehicle-fixed x,y,z coordinates of the selected wheel relative to the sprung mass CG

Wheel Image¶

The vehicle's wheels may be visualized as either a gray disk or using a bitmap (texture). In the latter case, a photograph of the wheels may be taken and used to provide a very realistic representation of the vehicle's wheels.

Figure 11-48: Typical wheel image.

When Wheel Image is selected from the Wheel option list, HVE displays a cascade menu containing two more options: New and Open.

NOTE: HVE includes many wheel image files for your use. If you wish to supply your own wheel image file, you must place it in the ...\Images\Vehicles\WheelTextures subdirectory.

New¶

The New option removes the existing wheel bitmap (if any) and replaces it with the default gray disk.

NOTE: Choose this option if you accidentally select the wrong wheel image file and need to remove it.

To remove the existing wheel image file, perform the following steps:

In the Vehicle Viewer, click on the desired wheel. The Wheel options for the selected wheel will be displayed.
Choose Wheel Image from the Wheel option list. The Wheel Image cascade menu will be displayed.
Choose New.

Any existing wheel image is removed from the selected wheel.

Open¶

The Open option displays the Wheel Image File Selection dialog and allows the user to assign a photographic image (texture map) of the wheel.

Figure 11-49: Image File Selection dialog, used for selecting wheel texture images.

To open a new wheel image and assign it to the current wheel, perform the following steps:

In the Vehicle Viewer, click on the desired wheel. The Wheel options for the selected wheel will be displayed.
Choose Wheel Image from the Wheel option list. The Wheel Image cascade menu will be displayed.
Choose Open. The Wheel Image File Selection dialog will be displayed.
Click on the Format option list to select the file format of the desired wheel image file.
Select a wheel image file from the list.
Press OK.

The selected wheel image is displayed on the selected wheel. Perform these steps for each wheel.

Source: HVE User's Manual (Version 5, Seventh Edition, Jan 2006), Chapter 11, pages 11-62..11-86 — updated against source code (HVEINV-64, Physics) 2026-07-05.

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