Steering angle in degrees, always around the local y-axis.

	// steer forwards
	collider.steerAngle = 0;

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Example() {
        collider.steerAngle = 0;
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Example() as void:
		collider.steerAngle = 0

At high velocities use only small steer angles; a few degrees should suffice.