Aftermarket performance brakes, such as these Baer brakes for a Jeep Wrangler JK, use larger than factory rotors and calipers to help compensate for larger, heavier tires and wheels. Adapter plates allow you to fit the calipers on the factory knuckles. The front calipers from Baer have six pistons while the rear calipers have four pistons. When it comes to aftermarket brakes, bigger is better, as long as everything still fits into the wheels. More pistons in the caliper help apply even pressure to larger brake pads. Baer, as well as others, fine-tune brake pad materials as well as machine rotors to help keep these larger, harder working brakes cool.