Should You Replace Rotors When You Replace Brake Pads?

Most drivers first notice brake wear because something feels off. Maybe the car shudders under braking, maybe there's a sound coming from your brakes like high pitched screeching, or maybe the dashboard brake-warning light quietly tattles on you. These are classic brake pad wear symptoms. And once you're at a shop, the natural next question shows up: If the brake pads need replacing, do the rotors automatically need it too?

The brake rotor (also known as the disc in disc brakes) is the circular piece of metal that is mounted to the wheel hub. When the driver steps on the brakes, the caliper pushes the brake pads on to the rotors, causing friction to slow down and stop the car. Some shops recommend changing both together since they both wear down over time. But unless the rotor is worn down, the pads and rotors don't necessarily need to be replaced at the same time. 

Brake rotors require replacement when they're warped (implicated by pulsing sensations during braking), deeply scored, or below minimum thickness. But the brake pads may wear out before the rotor. Rotor thickness must be within the manufacturer's discard specification, to safely dissipate heat, which it can be even when the pad has worn down. Measuring the rotors to make sure they still have a safe thickness and checking that information against your owners manual could help you save some money by waiting to replace them.

As mentioned earlier, some situations require rotor replacement. If you already observe deep grooves, surface cracks, overheating "blueing," or rotors that measure below their discard thickness, it's best to replace the rotors immediately. Brake rotors usually last a pretty long time (between 35,000 and 80,000 miles in normal use) but once metal becomes too thin, it can't dissipate heat properly.

If the rotors still have enough thickness, though, resurfacing becomes an option. Essentially, it's a process of machining a thin layer of metal off the surface to restore flatness to a warped rotor. Resurfacing is only viable when the rotor has enough material left with no defects like major warping or cracks. Resurfacing was especially common in the past, but many modern cars often have relatively thin rotors from the factory, leaving little room for resurfacing. As a result, some experts no longer recommend it, but it can still save you money in the right situations. Depending on the type of vehicle you own, Repair Pal estimates that rotor replacement costs between $559 and $730. Resurfacing, where still offered, can sometimes be as cheap as $15 to $40 per rotor (if you've removed the rotor yourself, that is). 

So which is better? Replacement gives you full thickness, renewed brake rotor lifespan and no more glazed brakes. Resurfacing is cheaper but only worth it if the rotors are still thick and undamaged. You don't need to replace rotors every time you replace pads. But if your rotors are beyond saving, replacing them is a pretty good solution.