# stiffness

> Multiplier for the WheelFrictionCurve.extremumValue and WheelFrictionCurve.asymptoteValue values (default 1).

## Definition

* **Type:** Property
* **Namespace:** [UnityEngine](/engine/6000.6/script-reference/unityengine.md)
* **Assembly:** UnityEngine.PhysicsModule

```csharp
public float stiffness { get; set; }
```

### Remarks

Changes the stiffness of the friction. Setting this to zero will completely disable all friction from the wheel.

Usually you modify `stiffness` to simulate various ground materials (e.g. lower the stiffness when driving on grass). Additional Resources: [WheelCollider.GetGroundHit](/engine/6000.6/script-reference/unityengine/wheelcollider/getgroundhit.md).

### Examples

```csharp
using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    public WheelCollider wheel;

    void Start()
    {
        wheel = GetComponent<WheelCollider>();
    }

    // When attached to the WheelCollider, modifies tire friction based on
    // static friction of the ground material.
    void FixedUpdate()
    {
        WheelHit hit;
        if (wheel.GetGroundHit(out hit))
        {
            WheelFrictionCurve fFriction = wheel.forwardFriction;
            fFriction.stiffness = hit.collider.material.staticFriction;
            wheel.forwardFriction = fFriction;
            WheelFrictionCurve sFriction = wheel.sidewaysFriction;
            sFriction.stiffness = hit.collider.material.staticFriction;
            wheel.sidewaysFriction = sFriction;
        }
    }
}
```