CODE EXAMPLE FOR CSHARP

unity wheelcollider antiroll

//Make it impossible to flip the car:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Antiroll : MonoBehaviour
{

	public WheelCollider WheelRL;
	public WheelCollider WheelRR;
	public WheelCollider WheelFL;
	public WheelCollider WheelFR;
    
	public float AntiRoll = 500f;

	public Rigidbody car;

	void Update()
	{
		if (WheelRL.isGrounded)
			car.AddForceAtPosition(-WheelRL.transform.up * AntiRoll, WheelRL.transform.position);
		if (WheelRR.isGrounded)
			car.AddForceAtPosition(-WheelRR.transform.up * AntiRoll, WheelRR.transform.position);
		if (WheelFL.isGrounded)
			car.AddForceAtPosition(-WheelFL.transform.up * AntiRoll, WheelFL.transform.position);
		if (WheelFR.isGrounded)
			car.AddForceAtPosition(-WheelFR.transform.up * AntiRoll, WheelFR.transform.position);
	}
}