Proper wheel balance ensures that the wheels, while spinning, do not have a heavy spot that can cause vibration and premature wear of tires, struts, shocks and other steering and suspension components. When combined with proper wheel alignment, balanced wheels ensure smooth and enjoyable driving.
The primary function of your cars suspension and steering systems is to allow the wheels to move independently of the car, while keeping it "suspended" and stable. Any play or uncontrolled motion in these systems results in a deterioration of handling and accelerated tire wear. Vehicle alignment is closely tied to the condition of the suspension and steering systems.
The brake system is actually composed of two kinds of systems---Hydraulics and Friction Materials. Here's what happens within these systems between the time your foot hits the brake pedal and your car stops.