Best way to add a MeshCollider at runtime without ruining physics?

Hey! I need to add a meshcollider to my vehicle at runtime but as soon as I do it will ruin physics entirely. The car will clip at 20mph, and roll over 4 or 5 times. Not it is not stabilizer bars, yes I am adding them, yes the CoG is correct.

Here is a snippet of the code

		//RIGIDBODY FIRST!
		car.AddComponent<Rigidbody>();
		Rigidbody r = car.GetComponent<Rigidbody>();
		r.interpolation = RigidbodyInterpolation.Interpolate;
		r.collisionDetectionMode = CollisionDetectionMode.Continuous;
		
		car.AddComponent<MeshCollider>();
		MeshCollider CCgb = car.GetComponent<MeshCollider>();
		CCgb.convex = true;
		//CAR COLLISION!
		Mesh carColliderMSH = tmdl_load.LoadTML (CarFile + "/" + CarName + "_COLLISION.tml",true,false).GetComponent<MeshCollider>().sharedMesh;
		CCgb.sharedMesh = carColliderMSH; //This messes it up =c
		//Calc physics?
		car.SetActive (false);
		car.SetActive (true);

Put the rigidbody to sleep first, then add the collider, then wake it up again.

The center of gravity of the rigid body is calculated from the colliders attached to it.

You will have to adjust the position of the center or gravity. eg.

rigidbody.centerOfMass += new Vector3(0,-0.3f,1f);