How to enable physic material on Wheel colliders !

If you're using the wheel collider and want to use the physic material to create different surfaces, well you'll found out it doesn't work ! Wheel colliders have special parameters to handle the wheel stiffness that ignore Physic Materials !

So I basically made a little script a year ago to solve my problem and then I lost it... I finally found it today while looking through a old external hard drive I was about to format, so I decided it would be better to share it before it got lost forever !

You have to apply this script to all your wheels !
Name this script: enableWheelPhysicMaterial.cs

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class enableWheelPhysicMaterial : MonoBehaviour
5. {
6.     private WheelCollider wheel;
7.     void Start()
8.     {
9.         wheel = GetComponent< WheelCollider >();
10.     }
11.     // static friction of the ground material.
12.     void FixedUpdate()
13.     {
14.         WheelHit hit;
15.         if (wheel.GetGroundHit(out hit))
16.         {
17.             WheelFrictionCurve fFriction = wheel.forwardFriction;
18.             fFriction.stiffness = hit.collider.material.staticFriction;
19.             wheel.forwardFriction = fFriction;
20.             WheelFrictionCurve sFriction = wheel.sidewaysFriction;
21.             sFriction.stiffness = hit.collider.material.staticFriction;
22.             wheel.sidewaysFriction = sFriction;
23.         }
24.     }
25. }

The original script was written in JavaScript so...

Code (JavaScript):

1. #pragma strict
2. public var wheel: WheelCollider;
3. function Start() {
4.     wheel = GetComponent.<WheelCollider>();
5. }
6. // static friction of the ground material.
7. function FixedUpdate() {
8.     var hit: WheelHit;
9.     if (wheel.GetGroundHit(hit)) {
10.         var fFriction: WheelFrictionCurve = wheel.forwardFriction;
11.         fFriction.stiffness = hit.collider.material.staticFriction;
12.         wheel.forwardFriction = fFriction;
13.         var sFriction: WheelFrictionCurve = wheel.sidewaysFriction;
14.         sFriction.stiffness = hit.collider.material.staticFriction;
15.         wheel.sidewaysFriction = sFriction;
16.     }
17. }

Enjoy !!

 

I know this post is like 5 years old, but it's MASSIVELY helpful, thanks!!!!

 

Slight modification so as not to override all your wheel's settings

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class enableWheelPhysicMaterial : MonoBehaviour
5. {
6.     private WheelCollider wheel;
7.  
8.  
9.     private float originalSidewaysStiffness;
10.     private float originalForwardStiffness;
11.  
12.    
13.  
14.  
15.     void Start()
16.     {
17.         wheel = GetComponent<WheelCollider>();
18.  
19.         originalSidewaysStiffness = wheel.sidewaysFriction.stiffness;
20.         originalForwardStiffness = wheel.forwardFriction.stiffness;
21.     }
22.     // static friction of the ground material.
23.     void FixedUpdate()
24.     {
25.         WheelHit hit;
26.         if (wheel.GetGroundHit(out hit))
27.         {
28.             WheelFrictionCurve fFriction = wheel.forwardFriction;
29.             fFriction.stiffness = hit.collider.material.staticFriction * originalForwardStiffness;
30.             wheel.forwardFriction = fFriction;
31.  
32.  
33.             WheelFrictionCurve sFriction = wheel.sidewaysFriction;
34.             sFriction.stiffness = hit.collider.material.staticFriction * originalSidewaysStiffness;
35.             wheel.sidewaysFriction = sFriction;
36.         }
37.     }
38. }
39.  

 

This is AWESOME. It works perfectly in Unity 2020.3.25. Add this script to the wheel colliders and then make a physics material and add that physics material to the objects you will drive on. Thanks SO much for this code!

 

FINALLY!! Thank you so much for the solution.