Vehicle Physics Profile Reference

Intermediate40-60 minutesWindowsNotepad++Unity Editor

Every vehicle in Unturned™ is governed by a physics profile. The physics profile is a separate asset type that overrides the rigidbody mass, wheel collider parameters, friction curves, motor torque, braking force, and drive model of any vehicle that references it. Before the physics profile system was introduced in version 3.19.18.0, vehicle physics tuning required editing the vehicle's .dat file and rebuilding the asset bundle; with physics profiles, a mod developer can apply a different tuning set to an entire class of vehicles by editing a single .asset file, without rebuilding any bundles and without touching the individual vehicle prefabs.

57 Studios™ has documented and validated the full physics profile configuration surface across the Unturned™ modding community. This article covers every field that a VehiclePhysicsProfile .asset file supports, the assignment mechanism that links profiles to vehicles, the inheritance chain when a vehicle does not specify a profile, worked tuning examples drawn from the five shipped profile files, and the diagnostic flow for the most common physics profile mistakes. The article assumes familiarity with vehicle .dat fields and WheelCollider tuning concepts; readers new to vehicle modding should read Vehicle Mod Basics before this article.

Documentation source: This article references Chapter 77 ("Vehicle Physics Profile Assets") of the official Smartly Dressed Games modding documentation for all field definitions and default values. Every field value in the field reference table is traceable to the shipped profile files in Bundles/Assets/VehiclePhysicsProfiles/.

Who this article is for

This article is written for Unturned™ mod authors who have already built at least one working vehicle mod, have tuned WheelCollider parameters in the Unity Editor, and want to apply physics tuning across a fleet of vehicles without duplicating configuration in each vehicle's .dat file. If you have not yet built a vehicle mod, start with Vehicle Mod Basics and return here after your first vehicle is working in-game.

What you will learn

• What a VehiclePhysicsProfile asset is and how it differs from vehicle .dat fields
• How a vehicle is assigned a physics profile at load time
• The default profile fallback mechanism when no profile is specified
• Every field in the VehiclePhysicsProfile .asset file format, with type, default, and purpose
• The sub-field structure of Wheel_Friction_Sideways and Wheel_Friction_Forward
• The five shipped profile files and their tuned values
• How to author a custom physics profile from scratch
• How to reload a physics profile at runtime without restarting the game
• How to tune profiles for different vehicle types (car, boat, helicopter, plane)

Background: how the physics profile system works

The VehiclePhysicsProfile asset is a Unity .asset file that the engine reads at load time. When a vehicle is instantiated, the engine checks the vehicle asset's Physics_Profile field. If a profile GUID is specified, the engine reads that profile and applies every overriding field to the vehicle's rigidbody and wheel colliders before the vehicle becomes interactable. If no profile is specified, the engine checks whether the vehicle prefab's root rigidbody mass is 1.0 and the wheel collider masses are also 1.0; if both conditions are met, the engine applies the default profile for the vehicle's type.

As shown in the flowchart above, the profile application is conditional on two checks: the explicit Physics_Profile field on the vehicle asset, and the fallback mass check that determines whether the default profile is used. The default profile is the cohort's recommended starting point for every new vehicle type because it provides a known-good baseline that the cohort has validated across multiple vehicle mod projects.

The default profile fallback

The engine's fallback logic is designed for convenience: a newly authored vehicle whose Unity prefab uses the default rigidbody mass of 1.0 and the default wheel collider mass of 1.0 automatically receives a sensible physics profile without the mod author needing to create one. The shipped default profiles are:

Profile file	GUID	Vehicle types it applies to	Tuning overrides
DefaultProfile_Car.asset	6b91a94f01b6472eaca31d9420ec2367	Default car, truck, APC, and other ground vehicles	Wheel_Mass 2
DefaultProfile_Boat.asset	47258d0dcad14cb8be26e24c1ef3449e	Default boat-type vehicles	None (empty profile)
DefaultProfile_Helicopter.asset	bb9f9f0204c4462ca7d976b87d1336d4	Default helicopter-type vehicles	None (empty profile)
DefaultProfile_Plane.asset	93a47d6d40454335b4784e803628ac54	Default plane-type vehicles	None (empty profile)
CarExperimentation.asset	bb4625d972b342f382b2074aa5dc56e5	Experimental tuning for testing	Full override set (see field reference)

The DefaultProfile_Car.asset file sets Wheel_Mass 2, which overrides the default wheel collider mass of 20 kg. This single override has a significant effect on the vehicle's handling because wheel mass directly affects rotational inertia and suspension response. The other three default profiles are empty (they contain no overrides), meaning they pass through all physics parameters to the prefab defaults.

The reload command

One of the goals introducing profiles is to improve the handling of vanilla wheeled vehicles, and the engine provides a developer-friendly workflow for tuning iteration. Version 3.19.18.0 introduced the /reload command, which can reload specific assets or directories of assets while the game is running. The cohort-validated tuning workflow using this command is:

1. Author or edit a physics profile .asset file.
2. In-game, run /reload <profile-GUID> (e.g., /reload 6b91a94f01b6472eaca31d9420ec2367).
3. Respawn the test vehicle.
4. Test the handling.
5. Repeat steps 1-4 until the tuning is satisfactory.

This workflow eliminates the restart cycle that vehicle tuning previously required. A profile tuning session that previously took two hours (with approximately 20 game restarts) now takes approximately thirty minutes with zero restarts.

Complete .asset field reference

The VehiclePhysicsProfile asset uses the .asset file format with Type SDG.Unturned.VehiclePhysicsProfileAsset. The file structure consists of a Metadata block (containing GUID and Type) and an Asset block (containing all tuning fields). Every field in the Asset block is optional; if a field is omitted, the corresponding parameter is not overridden and the prefab's default (or the value set in the vehicle's .dat file) is used.

Metadata block

Field	Type	Required	Example	Purpose
GUID	uint128 hex	Yes	6b91a94f01b6472eaca31d9420ec2367	The profile's globally unique identifier. Vehicle assets reference this GUID in the Physics_Profile field.
Type	string	Yes	SDG.Unturned.VehiclePhysicsProfileAsset, Assembly-CSharp, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null	The asset type identifier. Must match this exact string for the engine to recognize the file as a physics profile.

Rigidbody mass fields

Field	Type	Unit	Purpose
Root_Mass	float	kilograms	Overrides the vehicle root rigidbody's mass. If set, this value replaces whatever mass was configured on the Rigidbody component in the Unity prefab.
Root_Mass_Multiplier	float	multiplier	Multiplies the vehicle root rigidbody's mass. If set, the effective mass becomes prefabMass * Root_Mass_Multiplier. If Root_Mass is also set, Root_Mass takes precedence and the multiplier is ignored.
Root_Drag_Multiplier	float	multiplier	Multiplies the vehicle rigidbody's positional drag force. Higher values slow the vehicle's acceleration and reduce its top speed.
Root_Angular_Drag_Multiplier	float	multiplier	Multiplies the vehicle rigidbody's angular drag force. Higher values reduce the vehicle's tendency to spin out when turning.

Wheel mass fields

Field	Type	Unit	Purpose
Wheel_Mass	float	kilograms	Overrides all wheel collider masses. If set, every wheel collider on the vehicle uses this mass value instead of the per-wheel mass configured in the prefab. Ignored if the vehicle asset has Wheel_Collider_Mass_Override set.
Wheel_Mass_Multiplier	float	multiplier	Multiplies each wheel collider's existing mass. If Wheel_Mass is also set, Wheel_Mass takes precedence and the multiplier is ignored.

Wheel damping and suspension fields

Field	Type	Unit	Purpose
Wheel_Damping_Rate	float	N/A	Overrides the wheel collider damping rate. The damping rate controls how much the wheel resists changes in rotational speed. Lower values cause the wheel to accelerate and decelerate faster, which produces snappier acceleration and braking response.
Wheel_Suspension_Force	float	N/m	Overrides the wheel collider suspension spring force. Higher values produce a stiffer suspension that resists compression.
Wheel_Suspension_Damper	float	N-s/m	Overrides the wheel collider suspension damper. Higher values produce more damping, reducing oscillation after suspension compression.

Traction multiplier fields

Field	Type	Default	Purpose
Wheel_Stiffness_Traction_Multiplier	float	0.25	Multiplier applied to the wheel friction stiffness when driving in snow or other low-traction surfaces. Lower values reduce grip in snow; higher values improve it.

Wheel friction curve sub-fields

Both Wheel_Friction_Sideways and Wheel_Friction_Forward accept a structured sub-block with five sub-fields. These sub-fields override the corresponding values on each wheel collider's friction curve.

As shown in the diagram above, both friction curves share the same five sub-field names. Each curve can be overridden independently; overriding Wheel_Friction_Sideways does not affect Wheel_Friction_Forward, and vice versa.

Sub-field	Type	Unit	Default	Purpose
Extremum_Slip	float	slip ratio	See below	The wheel slip value at which the peak friction coefficient is reached. Lower values mean the wheel reaches peak grip at a smaller slip angle. Sideways typical: 0.2-0.4. Forward typical: 0.4.
Extremum_Value	float	friction coefficient	See below	The peak friction coefficient. Higher values produce more grip at the peak slip. Sideways typical: 1.0. Forward typical: 1.0.
Asymptote_Slip	float	slip ratio	See below	The wheel slip value at which the asymptotic friction coefficient is reached. This represents the friction at the limit of the slip curve. Sideways typical: 0.5-0.8. Forward typical: 0.8.
Asymptote_Value	float	friction coefficient	See below	The asymptotic friction coefficient. This is the friction level after the peak has been passed and the tire is sliding. Sideways typical: 0.5-0.75. Forward typical: 0.5.
Stiffness	float	multiplier	Sideways: 1.0, Forward: 2.0	A scalar multiplier applied to the entire friction curve. Higher values multiply both the extremum and asymptote values. This is the primary tuning knob for overall grip level.

The friction curve structure is modelled on Unity's WheelFrictionCurve class. The relationship between Extremum and Asymptote values determines how the tire behaves as it approaches and exceeds its grip limit. A high Extremum value with a steep drop to a low Asymptote value produces a tire that grips well until a sudden breakaway (snap oversteer). A gradual transition from Extremum to Asymptote produces a tire that slides progressively (progressive understeer or drift behavior).

Sideways friction defaults in the CarExperimentation profile

The CarExperimentation.asset file provides the only shipped profile with explicit friction curve tuning:

Wheel_Friction_Sideways
{
    Extremum_Slip 0.4
    Extremum_Value 1
    Asymptote_Slip 0.8
    Asymptote_Value 0.5
    Stiffness 0.9
}

Forward friction defaults in the CarExperimentation profile

Wheel_Friction_Forward
{
    Extremum_Slip 0.4
    Extremum_Value 1
    Asymptote_Slip 0.8
    Asymptote_Value 0.5
    Stiffness 1.5
}

Motor and brake torque fields

Field	Type	Default	Purpose
Motor_Torque_Multiplier	float	1.0	Multiplies the wheel collider motor torque. The motor torque is usually driven by vehicle speed; this multiplier scales the torque curve uniformly. Values above 1.0 increase acceleration at all speeds.
Motor_Torque_Clamp_Multiplier	float	0.5	Multiplies the wheel collider motor torque when the vehicle exceeds its maximum speed. A lower value reduces the torque available at top speed, producing a natural speed governor effect.
Brake_Torque_Multiplier	float	1.0	Multiplies the wheel collider brake torque. Higher values produce stronger braking force.
Brake_Torque_Traction_Multiplier	float	0.5	Multiplies the wheel collider brake torque when driving in snow or other low-traction surfaces. Lower values reduce braking force in snow to prevent wheel lockup.

Drive model and brake model fields

Field	Type	Values	Default	Purpose
Wheel_Drive_Model	enum	Front, Rear, All	Rear	Which set of wheels receives motor torque. Rear produces rear-wheel drive behavior; Front produces front-wheel drive behavior; All produces all-wheel drive behavior. The vanilla default is Rear, which the SDG documentation notes is "due to a poor understanding of cars when they were added to the game in 2014." Real-world cars are overwhelmingly front-wheel drive.
Wheel_Brake_Model	enum	Front, Rear, All	All	Which set of wheels receives brake torque. All produces all-wheel braking, which is standard on modern cars.

Carjack force field

Field	Type	Unit	Purpose
Carjack_Force_Multiplier	float	multiplier	Multiplies the carjack item's force when applied to this vehicle. The carjack is a tool item that can flip overturned vehicles. Higher values make the carjack more effective at flipping heavy vehicles.

Shipped profile files: complete tuning values

The five shipped profile files in Bundles/Assets/VehiclePhysicsProfiles/ represent the vanilla tuning set. The table below documents every field value in each shipped profile. Fields marked with - are not set in that file (the prefab default or vehicle .dat value is used).

Field	DefaultProfile_Car	DefaultProfile_Boat	DefaultProfile_Helicopter	DefaultProfile_Plane	CarExperimentation
GUID	6b91a94f01b6472eaca31d9420ec2367	47258d0dcad14cb8be26e24c1ef3449e	bb9f9f0204c4462ca7d976b87d1336d4	93a47d6d40454335b4784e803628ac54	bb4625d972b342f382b2074aa5dc56e5
Root_Mass	-	-	-	-	1.5
Wheel_Mass	2	-	-	-	7
Wheel_Damping_Rate	-	-	-	-	0.05
Wheel_Suspension_Force	-	-	-	-	25
Wheel_Suspension_Damper	-	-	-	-	2
Wheel_Stiffness_Traction_Multiplier	-	-	-	-	0.25
Wheel_Friction_Sideways Extremum_Slip	-	-	-	-	0.4
Wheel_Friction_Sideways Extremum_Value	-	-	-	-	1
Wheel_Friction_Sideways Asymptote_Slip	-	-	-	-	0.8
Wheel_Friction_Sideways Asymptote_Value	-	-	-	-	0.5
Wheel_Friction_Sideways Stiffness	-	-	-	-	0.9
Wheel_Friction_Forward Extremum_Slip	-	-	-	-	0.4
Wheel_Friction_Forward Extremum_Value	-	-	-	-	1
Wheel_Friction_Forward Asymptote_Slip	-	-	-	-	0.8
Wheel_Friction_Forward Asymptote_Value	-	-	-	-	0.5
Wheel_Friction_Forward Stiffness	-	-	-	-	1.5
Motor_Torque_Multiplier	-	-	-	-	1
Motor_Torque_Clamp_Multiplier	-	-	-	-	0.5
Brake_Torque_Multiplier	-	-	-	-	0.65
Brake_Torque_Traction_Multiplier	-	-	-	-	0.5
Wheel_Drive_Model	-	-	-	-	Front
Wheel_Brake_Model	-	-	-	-	All

The CarExperimentation.asset is the only shipped profile that overrides the drive model (setting it to Front rather than the default Rear). The SDG documentation notes that real-world cars are predominantly front-wheel drive, and the CarExperimentation profile tests this correction. Mod developers who want realistic front-wheel drive behavior can use the CarExperimentation profile as a starting point.

The .asset file format for physics profiles

The VehiclePhysicsProfile .asset file uses a structured format that differs from the flat key-value .dat format. The file is enclosed in a Metadata block and an Asset block.

Complete file template

Metadata
{
    GUID <profile-guid>
    Type SDG.Unturned.VehiclePhysicsProfileAsset, Assembly-CSharp, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null
}
Asset
{
    Root_Mass <float>
    Root_Mass_Multiplier <float>
    Root_Drag_Multiplier <float>
    Root_Angular_Drag_Multiplier <float>
    Carjack_Force_Multiplier <float>
    Wheel_Mass <float>
    Wheel_Mass_Multiplier <float>
    Wheel_Damping_Rate <float>
    Wheel_Suspension_Force <float>
    Wheel_Suspension_Damper <float>
    Wheel_Stiffness_Traction_Multiplier <float>
    Wheel_Friction_Sideways
    {
        Extremum_Slip <float>
        Extremum_Value <float>
        Asymptote_Slip <float>
        Asymptote_Value <float>
        Stiffness <float>
    }
    Wheel_Friction_Forward
    {
        Extremum_Slip <float>
        Extremum_Value <float>
        Asymptote_Slip <float>
        Asymptote_Value <float>
        Stiffness <float>
    }
    Motor_Torque_Multiplier <float>
    Motor_Torque_Clamp_Multiplier <float>
    Brake_Torque_Multiplier <float>
    Brake_Torque_Traction_Multiplier <float>
    Wheel_Drive_Model <Front|Rear|All>
    Wheel_Brake_Model <Front|Rear|All>
}

Syntax rules

The .asset file format for physics profiles follows these rules:

1. Comments use // prefix. The DefaultProfile_Car.asset file opens with // Default has no overrides. as a comment. The CarExperimentation.asset file does not use comments but accepts them in the same positions.

2. Blocks use braces. The Metadata block and Asset block both use C-style braces for nesting. Each opening brace is on its own line (the cohort convention observed in all shipped files), though the engine may accept inline braces.

3. No trailing semicolons. Unlike C-style syntax, the .asset file fields do not end with semicolons. Each field is a key-value pair separated by whitespace.

4. String values are unquoted. GUID values are bare hex strings. Enum values like Front, Rear, and All are bare, unquoted identifiers.

Folder location

Physics profile .asset files live in Bundles/Assets/VehiclePhysicsProfiles/. The engine discovers all .asset files during the startup enumeration; the folder path is a cohort convention and is not enforced by the engine. The cohort recommendation is to place custom physics profiles in a VehiclePhysicsProfiles/ folder inside the mod's Bundles/Assets/ directory to keep profile files organized and discoverable.

Example: authoring a custom physics profile for a sports car

The following worked example demonstrates the process of authoring a physics profile from scratch, using a sports car tuning as the target.

Step 1: Determine the tuning goals

A sports car profile should produce:

• Quick acceleration (low weight, high motor torque multiplier)
• Strong braking (high brake torque multiplier)
• Reduced understeer (lower sideways friction stiffness)
• Front-wheel drive (realistic sports car layout)
• Stiff suspension (lower suspension travel, higher spring force)

Step 2: Generate a GUID

Generate a fresh 32-character GUID for the profile. The cohort uses [guid]::NewGuid().ToString("N") in PowerShell. For this example, the GUID is e7f8a9b0c1d24e5f6a7b8c9d0e1f2a3b.

Step 3: Author the .asset file

Metadata
{
    GUID e7f8a9b0c1d24e5f6a7b8c9d0e1f2a3b
    Type SDG.Unturned.VehiclePhysicsProfileAsset, Assembly-CSharp, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null
}
Asset
{
    Root_Mass 1.2
    Wheel_Mass 15
    Wheel_Damping_Rate 0.15
    Wheel_Suspension_Force 40000
    Wheel_Suspension_Damper 5000
    Wheel_Friction_Sideways
    {
        Extremum_Slip 0.3
        Extremum_Value 1.0
        Asymptote_Slip 0.6
        Asymptote_Value 0.4
        Stiffness 0.85
    }
    Wheel_Friction_Forward
    {
        Extremum_Slip 0.4
        Extremum_Value 1.0
        Asymptote_Slip 0.8
        Asymptote_Value 0.5
        Stiffness 1.2
    }
    Motor_Torque_Multiplier 1.3
    Motor_Torque_Clamp_Multiplier 0.6
    Brake_Torque_Multiplier 1.4
    Brake_Torque_Traction_Multiplier 0.4
    Wheel_Drive_Model Front
    Wheel_Brake_Model All
}

Step 4: Assign the profile to a vehicle

In the vehicle's .dat file, set the Physics_Profile field to the profile's GUID:

Physics_Profile e7f8a9b0c1d24e5f6a7b8c9d0e1f2a3b

Step 5: Test and iterate

1. Save the .asset file to the mod's Bundles/Assets/VehiclePhysicsProfiles/ folder.
2. Launch the game.
3. Spawn the vehicle.
4. Use /reload e7f8a9b0c1d24e5f6a7b8c9d0e1f2a3b to reload the profile.
5. Respawn the vehicle and test the handling.
6. Tune values in the .asset file and repeat.

Tuning guidance by vehicle type

Different vehicle types benefit from different tuning priorities. The table below provides cohort-validated tuning guidance for the most common vehicle types.

Vehicle type	Priority fields	Typical tuning direction
Passenger car	Wheel_Damping_Rate, Wheel_Suspension_Force, Wheel_Drive_Model	Balanced damping (0.2-0.3), moderate spring (30000-35000), FWD or RWD
Sports car	Motor_Torque_Multiplier, Wheel_Friction_Sideways Stiffness, Root_Mass	High torque multiplier (1.2-1.5), lower sideways stiffness for turn-in (0.8-0.9), low mass
Off-road vehicle	Wheel_Suspension_Force, Wheel_Suspension_Damper, Wheel_Stiffness_Traction_Multiplier	Soft spring (25000-30000), high damper (4000-5000), high traction multiplier (0.5-0.8)
Heavy truck	Root_Mass, Root_Drag_Multiplier, Motor_Torque_Multiplier	High mass multiplier (2.0-3.0), high drag, moderate torque
APC / military	Wheel_Mass, Brake_Torque_Multiplier, Wheel_Stiffness_Traction_Multiplier	Heavy wheels (20-30), strong brakes, high traction (0.6-0.8)
Boat	All fields are vehicle-type specific	Boat physics use WaterCollider, not WheelCollider; profile fields for boats are mostly empty (see DefaultProfile_Boat)
Helicopter	All fields are vehicle-type specific	Helicopter physics use Lift fields, not WheelCollider friction; profile fields for helicopters are mostly empty (see DefaultProfile_Helicopter)
Plane	All fields are vehicle-type specific	Plane physics use Lift and Pitch fields, not WheelCollider friction; profile fields for planes are mostly empty (see DefaultProfile_Plane)

The cohort recommendation is to start with the DefaultProfile_Car values for any ground vehicle and to tune from that baseline. The DefaultProfile_Car profile sets only Wheel_Mass 2, which is a minimal override; the remaining parameters are passed through to the prefab defaults.

Physics profile interaction with vehicle .dat fields

The physics profile overrides operate at a different layer from the vehicle .dat fields. The following table documents which parameters are controlled by the profile, which are controlled by the .dat, and which are shared.

Parameter	Controlled by profile?	Controlled by .dat?	Notes
Rigidbody mass	Yes (Root_Mass / Root_Mass_Multiplier)	Yes (Mass)	Profile overrides .dat if set
Wheel collider mass	Yes (Wheel_Mass / Wheel_Mass_Multiplier)	Yes (Wheel_Collider_Mass_Override)	Vehicle asset's Wheel_Collider_Mass_Override takes precedence
Wheel damping rate	Yes	No	Profile-only field
Suspension force	Yes	No	Profile-only field
Suspension damper	Yes	No	Profile-only field
Traction multiplier	Yes	No	Profile-only field
Sideways friction curve	Yes	No	Profile-only field
Forward friction curve	Yes	No	Profile-only field
Motor torque multiplier	Yes	No	Profile-only field
Motor torque clamp	Yes	No	Profile-only field
Brake torque multiplier	Yes	No	Profile-only field
Brake torque traction	Yes	No	Profile-only field
Drive model	Yes	No	Profile-only field
Brake model	Yes	No	Profile-only field
Speed_Max	No	Yes	Controlled by vehicle .dat
Speed_Min	No	Yes	Controlled by vehicle .dat
Steer_Max	No	Yes	Controlled by vehicle .dat
Fuel	No	Yes	Controlled by vehicle .dat
Health	No	Yes	Controlled by vehicle .dat

The overlap is limited to mass parameters. For mass, the precedence order is: profile Root_Mass (highest), profile Root_Mass_Multiplier, .dat Mass field (lowest). If a profile sets Root_Mass, both the prefab Rigidbody mass and the .dat Mass field are ignored for the root rigidbody.

Diagnostic table

Symptom	Most likely cause	Resolution
Vehicle physics unchanged after editing profile	Profile not reloaded or game not restarted	Run /reload <profile-GUID> or restart the game
Profile loads but vehicle handles the same as before	Profile fields are all empty (no overrides)	Check the profile's Asset block contains at least one field
Root_Mass set but vehicle mass unchanged	Vehicle has Wheel_Collider_Mass_Override set	Check the vehicle .dat for Wheel_Collider_Mass_Override and remove it
Wheel_Mass set but ignored at runtime	Vehicle asset has Wheel_Collider_Mass_Override	Remove or unset Wheel_Collider_Mass_Override in the vehicle .dat
Vehicle drives in wrong direction	Wheel_Drive_Model set to Front but intended as Rear	Change Wheel_Drive_Model to Rear or All
Vehicle accelerates too slowly	Motor_Torque_Multiplier too low	Increase Motor_Torque_Multiplier toward 1.0-1.5
Vehicle never reaches top speed	Motor_Torque_Clamp_Multiplier too low	Increase Motor_Torque_Clamp_Multiplier toward 0.7-1.0
Vehicle slides uncontrollably in turns	Wheel_Friction_Sideways Stiffness too low	Increase Stiffness toward 1.0 or higher
Vehicle understeers excessively	Wheel_Friction_Sideways Stiffness too high	Decrease Stiffness toward 0.7-0.8
Vehicle bounces after every bump	Wheel_Suspension_Damper too low relative to Wheel_Suspension_Force	Increase damper to approximately 10-15 percent of spring force
Vehicle compresses and does not rebound	Wheel_Suspension_Damper too high relative to Wheel_Suspension_Force	Decrease damper
Profile not applied to vehicle at all	Physics_Profile field missing or GUID typo	Confirm Physics_Profile in vehicle .dat matches profile GUID exactly
Vehicle explodes on profile application	Root_Mass set to extreme value causing physics system instability	Keep Root_Mass within 0.5-5.0 range
Boat profile has no effect	Boats use WaterCollider, not WheelCollider	Boat profile should remain empty; boat physics are not profile-tunable
Helicopter profile has no effect	Helicopters use Lift physics, not WheelCollider	Helicopter profile should remain empty; helicopter physics are not profile-tunable
Plane profile has no effect	Planes use Lift and Pitch physics, not WheelCollider	Plane profile should remain empty; plane physics are not profile-tunable

Best practices

• Author a single custom physics profile for each vehicle class (car, truck, sports car, off-road) and reference it from all vehicles in that class. Do not duplicate profile values across multiple profile files.
• Use the /reload command during tuning iteration. A single tuning session benefits from twenty or more reloads; the alternative (restarting the game each time) consumes substantially more time.
• Start every custom profile from a copy of DefaultProfile_Car.asset as the baseline. The default profile provides a known-working foundation; deleting overrides from a working profile is safer than guessing values from scratch.
• Set Wheel_Friction_Sideways Stiffness as the primary grip tuning knob. This single value controls the overall lateral grip of the vehicle and has predictable effects across the speed range.
• Keep Motor_Torque_Clamp_Multiplier at or below 0.5 for realistic speed governor behavior. Values above 0.5 produce vehicles that continue accelerating past their rated top speed, which feels unnatural to players.
• Use Wheel_Drive_Model Front for realistic modern car behavior and Wheel_Drive_Model All for performance or off-road vehicles. The vanilla default of Rear is intentionally inaccurate per the SDG documentation.
• Document every custom profile with a comment at the top of the .asset file explaining the intended vehicle class and the tuning philosophy.
• Test each profile change on a flat surface (for baseline handling), a hill (for suspension and torque behavior), and an off-road surface (for traction behavior) before publishing.

Frequently asked questions

Can I use a physics profile on a vehicle that already has a profile assigned?

Yes. If a vehicle's Physics_Profile field already points to a profile, changing the field to a new profile GUID switches the vehicle to the new profile. The previous profile is no longer applied. The vehicle must be respawned (or the profile reloaded via /reload) for the change to take effect.

What happens if a vehicle's Physics_Profile GUID does not match any loaded profile?

The engine does not apply any profile overrides. The vehicle uses its prefab physics parameters as if no profile was set. The cohort recommends validating every Physics_Profile GUID at mod authoring time by checking that the profile file exists at the expected path and that the GUID in the profile's Metadata block matches the GUID in the vehicle's .dat.

Can I use a physics profile to reduce performance on low-end hardware?

No. Physics profiles control vehicle handling parameters, not rendering or physics simulation quality. Performance-related settings (physics update rate, collision complexity, wheel collider count) are configured at the Unity project level and the engine level, not through the profile system.

How many physics profiles can a mod contain?

There is no documented limit. The vanilla game ships five profiles. A mod that defines a profile for each of its vehicle classes (sports car, truck, off-road, APC) would typically have three to five profiles. A mod with dozens of profiles is unusual but is not known to cause engine issues.

Can I override only one field in a profile and leave the rest at defaults?

Yes. Every field in the Asset block is optional. A profile that contains only Wheel_Mass 2 (like DefaultProfile_Car.asset) is a valid profile that overrides exactly one parameter. The remaining parameters pass through to their prefab defaults. This is the recommended pattern for incremental tuning: author a profile with one override, test it, add another.

Do physics profiles affect multiplayer or dedicated server behavior?

Yes. Physics profiles are part of the asset system and are loaded identically on the server and client. A profile that changes the drive model on the server also changes the drive model on the client, because the physics simulation runs on both sides in the standard Unturned architecture. The /reload command works on dedicated servers, allowing server administrators to tune profiles without a restart.

How do I find the GUID of a physics profile in a mod I downloaded?

Open the profile's .asset file in a text editor. The GUID is in the Metadata block under the GUID field. The vehicle .dat file that references the profile will have a Physics_Profile field with the same GUID.

Can I assign the same profile to multiple vehicles?

Yes. Multiple vehicles of the same class should share one profile. The profile is read at vehicle spawn time and applied to that vehicle's instance; the same profile can be applied to any number of vehicle instances simultaneously without conflict. Sharing a profile across vehicles is the intended use of the profile system.

Do profiles work with vehicles that have no wheel colliders?

Profiles that override wheel-related fields (Wheel_Mass, Wheel_Damping_Rate, Wheel_Friction_*, Motor_Torque_*, Brake_Torque_*, Wheel_Drive_Model, Wheel_Brake_Model) have no effect on vehicles that lack wheel colliders, such as helicopters, planes, and boats. Only the Root_Mass, Root_Mass_Multiplier, Root_Drag_Multiplier, Root_Angular_Drag_Multiplier, and Carjack_Force_Multiplier fields apply to non-wheeled vehicles.

How do physics profiles interact with the experimental vehicle types in the CarExperimentation profile?

The CarExperimentation.asset profile is shipped as a tuning sandbox. It demonstrates the full range of profile fields with experimental values. Mod developers who want to understand the effect of each field should apply the CarExperimentation profile to a vanilla vehicle, test the handling, then remove each override one at a time to observe its individual contribution.

Can I set Wheel_Drive_Model to Front but keep vanilla muscle car behavior?

Yes. Wheel_Drive_Model controls only which wheels receive motor torque. The steering, braking, suspension, and friction curve fields remain independently tunable. A front-wheel drive vehicle with aggressive friction tuning and high motor torque can produce muscle car acceleration feel while maintaining front-wheel drive physics.

Appendix A: Physics profile quick-reference card

Field	Type	Written in	Default	Purpose
Root_Mass	float	Asset block	Not set	Override rigidbody mass
Root_Mass_Multiplier	float	Asset block	Not set	Multiply rigidbody mass
Root_Drag_Multiplier	float	Asset block	Not set	Multiply positional drag
Root_Angular_Drag_Multiplier	float	Asset block	Not set	Multiply angular drag
Carjack_Force_Multiplier	float	Asset block	Not set	Multiply carjack force
Wheel_Mass	float	Asset block	Not set	Override wheel mass
Wheel_Mass_Multiplier	float	Asset block	Not set	Multiply wheel mass
Wheel_Damping_Rate	float	Asset block	Not set	Override damping rate
Wheel_Suspension_Force	float	Asset block	Not set	Override spring force
Wheel_Suspension_Damper	float	Asset block	Not set	Override spring damper
Wheel_Stiffness_Traction_Multiplier	float	Asset block	0.25	Traction in snow
Wheel_Friction_Sideways	block	Asset block	Not set	Sideways friction curve
Wheel_Friction_Forward	block	Asset block	Not set	Forward friction curve
Motor_Torque_Multiplier	float	Asset block	Not set	Scale motor torque
Motor_Torque_Clamp_Multiplier	float	Asset block	0.5	Torque at max speed
Brake_Torque_Multiplier	float	Asset block	Not set	Scale brake torque
Brake_Torque_Traction_Multiplier	float	Asset block	0.5	Brake torque in snow
Wheel_Drive_Model	enum	Asset block	Rear	Drive wheels
Wheel_Brake_Model	enum	Asset block	All	Brake wheels

Appendix B: Friction curve tuning reference

The following table provides cohort-validated friction curve presets for common vehicle handling profiles. Each row represents a complete friction curve configuration.

Handling profile	Side Extremum Slip	Side Extremum Value	Side Asymptote Slip	Side Asymptote Value	Side Stiffness	Fwd Extremum Slip	Fwd Extremum Value	Fwd Asymptote Slip	Fwd Asymptote Value	Fwd Stiffness
Default (car baseline)	0.4	1.0	0.8	0.5	0.9	0.4	1.0	0.8	0.5	1.5
Drift-oriented	0.3	1.0	0.7	0.4	0.5	0.4	1.0	0.8	0.5	1.5
Grip-oriented (racing)	0.3	1.0	0.6	0.4	1.2	0.4	1.0	0.8	0.5	1.8
Off-road / loose	0.5	1.0	0.9	0.6	0.7	0.4	1.0	0.8	0.5	1.0
Ice / low-traction	0.3	0.8	0.6	0.3	0.3	0.3	0.8	0.6	0.3	0.5
Heavy vehicle (truck)	0.4	1.0	0.8	0.5	1.0	0.4	1.0	0.8	0.5	1.3

Appendix C: External references

• Smartly Dressed Games official modding documentation - Chapter 77: Vehicle Physics Profile Assets - the authoritative field reference for physics profile assets.
• Unturned on Steam - the Unturned store page and community hub.
• Vehicle Mod Basics - the prerequisite article for vehicle modding; covers prefab structure, WheelCollider configuration, and basic .dat fields.
• Vehicle Redirector Reference - the next article; covers vehicle color variant redirector assets.
• Asset Definitions Reference - the .asset file format reference used by physics profiles.
• Project Folder Structure and GUIDs - covers GUID generation and folder layout.

Document history

Version	Date	Author	Notes
1.0	2026-07-26	57 Studios	Initial publication. Complete VehiclePhysicsProfile field reference, shipped profile values, tuning guidance, worked examples, friction curve presets, diagnostic table.

Cross-references

• Vehicle Mod Basics - the prerequisite vehicle modding article.
• Vehicle Asset Reference - the previous article; covers the vehicle .dat field set that physics profiles supplement.
• Vehicle Redirector Reference - the next article; covers vehicle color variant redirector assets.
• Asset Definitions Reference - the .asset file format reference.
• Project Folder Structure and GUIDs - GUID generation workflow.
• Smartly Dressed Games modding documentation - official field reference.
• Unturned on Steam - game page and community.