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Recently, I was helping my friend rotate their tires and do some routine vehicle maintenance. They mentioned the brakes had been making more noise than usual. When I took a look, I saw that the rear brake pads were worn almost to nothing. Luckily, they had some replacement pads on hand. But in normal circumstances, your front brake pads should wear much faster than your rears. This automotive mystery had an answer that surprised me.

Your brake pads, electronic stability control, and traction control

Toyota 4Runner TRD brake pads
Toyota 4Runner TRD brake pads | Toyota

The brake pads had roughly 40,000 miles on them. Although the rear ones were gone, the front pads were still usable. Usually, the front pads wear quickly because braking shifts the car’s weight forward, which means the front rotors need to be stronger.

But there is a reason why rear brake pads can wear faster than expected: traction control and electronic stability control. This is because your Anti-lock braking system (ABS) is linked to the ESC and traction control.

These systems receive data from various sensors, including ones in your braking system. Traction control manages wheelspin, while electronic stability control governs handling. If the car thinks it’s sliding out of control, it automatically applies specific brakes to bring itself back in line.

Because of this, ESC also sharpens a car’s handling. And that’s where the rear brake pads come in. Braking the rear wheels prevents understeer and tightens up turns. It’s not full-on a torque-vectoring or even a limited-slip differential, but the basic principles are the same. The system may use the rear brakes to mitigate some of the forward nose-diving that normally happens when the car stops.

On top of that, because rear brake pads typically deal with less force than the front ones, they’re usually thinner. Combined with the electronic stability control and traction control, and you have a formula for accelerated rear brake pad wear.

Uneven brake pad wear isn’t always normal

A car mechanic inspects the underside of a car to see if the axles are okay.
Mehcanic working || Luke Sharrett/Bloomberg via Getty Images

However, there are situations where brake pad wear is abnormal. Specifically, if the pads on one wheel or one side are especially worn. That points to an issue with the braking system itself.

Some of this uneven wearing may be the brake rotor’s fault. If the rotor’s surface isn’t even, it causes the pads to wear unevenly too. Brake pedal vibration, excessive noise, and extensive rotor scoring all point to an uneven or warped rotor.

Other potential problems can be pinpointed by looking at the worn brake pads themselves. If the inner pad is more worn, the caliper piston isn’t backing off properly, keeping the pad in contact with the rotor. A worn outer pad means it’s not backing out with the caliper after releasing the pedal. And if the pad material tapers, the pad is misaligned, or the caliper’s components are seizing.

How to repair these issues

A technician at the Raymond Chevrolet dealership in Antioch, Illinois, working on vehicle recall paperwork
A Chevrolet dealership technician | John Gress/Corbis via Getty Images

If the rotor itself is the issue, the easiest solution is to resurface it, machining the surface back to a uniform thickness. But you can only do that so many times before the rotor becomes too thin to be effective. At that point, replacement is the only option.

If it’s an issue with the brake caliper itself, it may require replacing the entire caliper or a few key components, such as the rubber piston seal or slide pin. It’s also possible your brake lines may be causing the problem—check that none of the hoses are leaking.

If it’s a misaligned brake pad, replace the pads on both sides of the axle and install new retaining hardware. Otherwise, the uneven wear will continue or even worsen.

Next, read how to clean and re-gap your spark plugs or learn all about uneven brake pad wear in the video below:

Editor’s Note: This article was originally written by Matthew Skwarczek. It was updated in June 2023 to meet our latest editorial standards.