How do I set the center of mass for my vehicle?

Im making a racing game and 7/8of my cars are working perfectly: what I mean is, they are driving well, their center of mass is good, but it comes down to one vehicle. See, im using the catamount car from unitys car tutorial asset with my own script. The driving is working well, but the problem is, whenever I turn hard to right/left, it just bicycles.(goes on 2 wheels.) I dont know,if its the COM, or a problem with wheel colliders. Heres a snippet of my COM code so you can see.

#pragma strict
var centerOfMass : Vector3
function Start (){
GetComponent.<Rigidbody>.centerOfmass = centerOfMass;
SetValues();
}

The easiest way to do this is add a child empty object called Com or something. Then in your script set the empty’s local position to the rigid body’s center off mass. This makes it easily adjustable and not hardcoded, and the script that sets the center off mass will be reusable. Just remember to use localPosition, as the center of mass property will only work with local coodinates.