When do brakes need to be replaced?

Knowing that your brakes are in good shape is essential for peace of mind when driving. Brakes in a car use friction to slow down or stop the rotation of the wheels. As a result of the friction and generated heat, brakes wear out. See the photo of worn-out and new brake pads.
Disc brakes diagram: caliper, rotor, pads, thickness Disc brakes.
If the brakes wear out past the safe limit, braking performance will be reduced and the vehicle will be unsafe to drive. Rust, overheating and other problems can also hinder the effectiveness of the brakes. For this reason, brakes need to be inspected in regular mileage or time intervals and replaced if worn out or if there is some other issue that might prevent them from working properly.

How often do brakes need replacing? Car makers don't specify the mileage to replace brakes in the maintenance schedule; instead, they list brake inspections that must be done during regular services. Typically, brake inspections are done when wheels are removed, because brake components are not visible with wheels on the car. For example, the maintenance schedule for the 2020 U.S. Toyota Camry advises to "Visually inspect brake linings/drums and brake pads/discs" every 5,000 miles or 6 months when doing the tire rotation.

What is a brake inspection? Car manufacturers provide technical guidelines for mechanics on the brake inspection process and specifications for brake components.
Measuring brake rotor thickness Measuring brake rotor thickness.
Examples include minimum rotor (disc) thickness and minimum brake pad friction material (lining) thickness. Based on the guidelines, a mechanic can determine whether your brakes need to be replaced or not, and whether your car is safe to drive.

What does it mean when your car needs new brakes? It means that the brake parts that are worn out (e.g. pads and rotors) need to be replaced with new parts. Brakes are replaced on both wheels of the same axle at the same time. In some cases, additional parts of the braking system might need to be replaced. For example, if a mechanic finds that the brake caliper is leaking or not functioning properly, it will need to be replaced too.

How long do brakes last? On average, disc brakes last for 30,000-50,000 miles. Rear drum brakes can last longer, sometimes up to 150,000 miles. Brakes in hybrid and electric cars tend to last longer than in regular cars because some of the braking is done by an electric motor/generator (regenerative braking). If the vehicle is parked for extended periods of time, especially in wet weather, brake rotors and other parts tend to rust. This problem is more common in regions where road salt is used in the winter. Rust causes brakes to wear prematurely. If some of the brake components (e.g. guide pins) are sticking, the brakes may also wear sooner. For this reason, brakes may need servicing between replacements.

Do the rear or front brakes last longer? Front brakes do most of the braking and, in some cars, front brakes wear out faster, but in others, rear disc brakes wear out sooner. It depends on the design, material and size of the pads, load and many other factors.

Should you replace the front and rear brakes at the same time? No, it's not necessary. Front or rear brakes can be replaced independently of each other. Of course if, for example, you are replacing your front brakes and the rear brakes are getting low, it might be a good idea to replace them together to save time.

Disk brakes:

Most cars have disc brakes on all four wheels. A typical brake replacement on one axle includes replacing a set of brake pads and both rotors, as well as related hardware (shims, springs, etc.).
Disc brakes diagram: caliper, rotor, pads, thickness Disc brakes.
Replacing brakes also includes servicing the components that need to be serviced, for example, cleaning and lubricating guide (slide) pins.

In an average car, replacing brakes (pads, rotors and hardware) on one axle costs from $400 to $750. The price depends on where you decide to do the repairs and what kind of parts are used. Replacing brakes at a dealership using original (OEM) parts is more expensive. Doing the job in an independent repair shop with aftermarket parts is usually cheaper.

Are aftermarket brakes as good as OEM? Some aftermarket brake parts are of high quality while others are cheap for a reason. Considering this, OEM parts are always a safe choice. It's also a good idea to use OEM parts while the vehicle is under warranty. If you want to use aftermarket parts, request high quality parts from a reputable brand. Although in general, aftermarket parts are cheaper, we have seen many cases where OEM prices were close or even cheaper than aftermarket.

Is it better to use new rotors or resurface the old ones? In some cases, old brake rotors can be resurfaced or 'machined' instead of replacing. In this case, replacing brakes on one axle includes replacing brake pads and related hardware, machining both rotors and servicing all related components.
New pads and rotors New pads and rotors.
Car makers specify the requirements (e.g. minimum rotor thickness) when brake rotors can be machined and when they must be replaced. Replacing rotors is always a preferred option, since machining makes rotors thinner. Plus, the overall price of the brake replacement is usually not much different whether the rotors are machined or replaced.

There are situations where your mechanic may recommend reusing the brake pads and replacing or machining the brake rotors; for example, if the brake rotors are warped or rusted, but the brake pads are still in good shape. In other cases, only the brake pads can be replaced if the rotors are in good condition and can be safely reused. When deciding between different repair options, safety is always the first consideration.

Parking brake: In most cars, rear disc brakes serve as parking brakes. Other vehicles with rear disc brakes have separate mini drum parking brakes built within the rear disc hubs. Separate parking brakes are also replaced when they are worn out. The parking brake might need to be adjusted whenever the rear brakes are serviced or replaced. Many modern vehicles have an electronic parking brake (EPB) with electric parking brake actuators that are attached to the rear calipers. Whenever the rear brakes are serviced or replaced, the electronic parking brake might need to be set into service mode.

Drum brakes:

Drum brakes are known for their longevity. In modern vehicles, drum brakes are only used on the rear axle. Rear drum brakes also function as parking brakes.
Drum brakes diagram Rear drum brakes.
The parking brake mechanism is connected to the rear drum brakes via parking brake cables.
In the case of drum brakes, replacing brakes means changing the brake shoes and drums if the drums are worn out, as well as replacing the hardware that needs to be replaced. As an option, drums can be resurfaced (machined). Car makers specify the minimum inside diameter of the drum (see the photo how it is measured), the minimum thickness of the brake shoe linings and a few other measurements. Due to the complexity, It takes a bit more time to replace the drum brakes than disc brakes. After replacing the drum brakes, they need to be adjusted. The parking brake mechanism might need to be adjusted too. Replacing rear drum brakes (shoes, drums and hardware) costs from $420 to $750 in an average car.