Where there’s a caliper, there’s a rotor, and where you have both, you have a disc brake. Your BMW Rotors are the shiny discs that spin with your wheels. They’re visible just behind the wheel or wheel cover on your vehicle. Since the caliper stays put, and is firmly attached to the steering knuckle, when it grips the rotor as you apply your brakes, your car comes to a stop.

BMW rotors are usually vented, which means they’re actually made up of two discs with a bunch of grooves in between. These grooves help the rotor dissipate heat more quickly. When you stomp on the brakes, your BMW rotors can overheat and warp, which can cause your steering wheel to shimmy even when you aren’t applying the brakes. Sometimes the warping can be removed by “turning” the rotors on a brake lathe, but other times the BMW rotors have to be replaced.