The car goes sideways because the load on the rear tires isn't equal. Ever wonder why the right tire is always the one that spins on a one wheel peal? For every action there is an equal oposite reaction. Engine rotational torque causes the body to go down on the right. This forces the axle up into the wheel well. Less load on the right allows it to spin. Now with a suregrip the right still has less load. The left has more traction. This drives the car to the right. Not metion most cars are drivers side heavy which adds to the problem. Get the load adjusted on the rear tires and it'll go straight.
Doug