Height of the centre of mass relative to the wheelbase determines load transfer between front and rear. The car's momentum acts at its centre of mass to tilt the car forward or backward, respectively during braking and acceleration. Since it is only the downward force that changes and not the location of the centre of mass, the effect on over/under steer is "opposite" to that of an actual change in the centre of mass. When a car is braking, the downward load on the front tires increases and that on the rear decreases, with corresponding change in their ability to take sideways load.