Get Total Rotation of Wheel Collider

There's no built in rotation counter, but we can keep track of it ourselves using the wheel's RPM;

 private float totalRotations = 0f;
 
 void LateUpdate ()
 {
     //Find the current RPM and convert to rotations per second
     float rps = wheel.rpm / 60f;
     //Scale by time since the last frame and add to total
     totalRotations += rps * Time.deltaTime;
 
     //Just multiply by 360 to convert to degrees
     float totalDegrees = totalRotations * 360f;
     visual.localRotation = Quaternion.Euler (new Vector3 (totalDegrees, 0f, 0f));
 }