When you modify your vehicle with custom wheels and performance tires, you may need to upgrade your brakes at the same time. Stock brakes work fine with the factory rims and rubber, but as soon as you go up in size, the leverage on the wheel increases, and the vehicle's center of gravity changes as well, both of which impact braking effectiveness. Also, if the tires are stickier, your standard brakes may not be able to take advantage of the increased adhesion. Conversely, if you upgrade the brakes without improving the rubber that meets the road, you may not see a big difference in stopping ability. That's because brakes aren't really what stop your vehicle—tires do. What brakes do is slow the rotation of the wheels and tires.