The amount a wheel leans in or out at the top is called "camber". As the car turns and the body leans the tire can lose traction as it no longer is making full contact with the road. When the top of the wheel leans in toward the center of the car it's called negative camber, typically a necessary set-up for competition or hard driving. Negative camber at the rear can be just as important as the front and stock rear is often at 0º or even positive. The control of rear camber is by the outer bracket for the rear radius arm which is bolted to the rear subframe.