Brakes are the one system on the car that nobody wants to discover is worn. They also fail gradually, which is the problem: the car stops a little less sharply each month, you adapt without noticing, and the first clear sign is a noise at the worst possible moment.
This guide covers how to tell when pads are due, what the different sounds and feelings mean, how long pads typically last, and what to keep a record of.
It is general information. If your brakes feel wrong, have them inspected rather than diagnosing from a blog post.
How Brake Pads Wear
When you press the pedal, hydraulic pressure pushes the pads against a spinning disc (also called a rotor). Friction turns the car's movement into heat, and a thin layer of pad material wears away every time.
Two things wear in that process:
- The pads, which are designed to be replaced
- The discs, which wear more slowly but also have a minimum thickness
Most cars also have **brake fluid** in the system, which does not wear out in the same way but does age. More on that below.
The Minimum Thickness
New pads typically have **around 10 to 12 mm** of friction material on the backing plate.
| Pad thickness | What it means |
|---|---|
| 8 mm and above | Plenty left |
| 5 to 7 mm | Normal wear, keep an eye on it |
| 3 to 4 mm | Plan a replacement soon |
| 3 mm or less | Replace now |
| 2 mm or less | Past the point most workshops would let a car leave |
Some manufacturers publish their own minimum, so the handbook wins if it says something different.
You can often see the outer pad through the spokes of an alloy wheel with a torch. The inner pad, which frequently wears faster, is hidden. A proper check means the wheel comes off, which is why it is worth asking for pad measurements in millimetres at every service rather than a vague "they are fine".
Sounds and Feelings: What Each One Means
A high pitched squeal when braking
Many pads have a small metal tab, called a wear indicator, that touches the disc when the pad is nearly finished. It makes a squeal on purpose. If the noise is consistent and appears when you brake, treat it as a warning.
A squeal after rain, on the first few stops of the morning, or after the car has been parked for a while is often just moisture or a surface rust film on the discs. That one goes away after a few gentle stops.
Grinding
A harsh grinding or scraping noise usually means the friction material is gone and the metal backing plate is touching the disc. At that point you are damaging the discs as well, and stopping distances get longer. Get it seen quickly.
A warning light
Many European cars have electronic wear sensors in the pads that trigger a dashboard light. The sensor is often a one use part and is replaced with the pads.
Vibration through the pedal or steering wheel
A pulsing pedal or a shaking wheel under braking usually points to the discs, not the pads. Uneven pad deposits or uneven disc thickness are the common causes, often called "warped discs".
The car pulls to one side
Pulling under braking can mean a sticking caliper, uneven pad wear between sides, or a problem with tyres or alignment. It needs a look, because a sticking caliper will wear one side out fast.
A soft or sinking pedal
This is not a pad problem. A spongy pedal that travels further than usual suggests air in the system, old fluid or a leak. **Do not keep driving on a pedal that sinks.**
How Long Brake Pads Last
You will see figures quoted anywhere from 25,000 to 70,000 miles, and that wide range is honest. The things that move it:
- Driving style: late hard braking wears pads far faster than lifting off early
- Where you drive: stop start city traffic and hilly roads wear pads much faster than motorway miles
- Vehicle weight: heavier cars, loaded cars and anything towing use more brake
- Pad compound: performance pads often trade life for bite
- Front or rear: the front brakes do most of the work, because weight shifts forward when you slow down, so front pads usually wear out first
The only figure that really matters is your own. If you know your pads were fitted at 41,000 miles at 11 mm, and measured 6 mm at 63,000, you can estimate roughly when they will reach 3 mm.
Discs Wear Too
Discs have a minimum thickness, usually stamped on the disc itself. Workshops will often recommend replacing discs with every second set of pads, or every set on some modern cars that use thinner discs. Replacing discs and pads together on an axle is common and avoids new pads bedding into a worn, uneven surface.
Always replace pads in pairs on the same axle, both sides together, so the car brakes evenly.
Brake Fluid: The Forgotten Part
Brake fluid absorbs moisture from the air over time. Water in the fluid lowers its boiling point, which matters under heavy braking, such as a long descent, and it can corrode parts inside the system.
Many manufacturers specify a fluid change **every two to three years**, regardless of mileage. It is one of the jobs most often missed in a maintenance schedule, precisely because nothing visible goes wrong until it does.
Electric and Hybrid Cars
Regenerative braking means the motor does most of the slowing down, so pads on an electric car can last a very long time.
The catch is the opposite problem. Brakes that are barely used can develop rust on the discs and sticking caliper slides. Electric cars still need their brakes inspected and cleaned, and their fluid changed on time. Some owners deliberately brake firmly now and then to keep the surfaces clean, which is worth asking your workshop about.
After New Pads Are Fitted
New pads and discs need a short bedding in period to transfer an even layer of pad material onto the disc. Workshops usually do this or tell you how. In general, avoid sudden heavy stops for the first couple of hundred miles unless you need to.
Keep the receipt. Brake work is one of the first things a buyer looks for in a full service history.
Keeping Track With Autoteca
The hard part of brake maintenance is memory. When were the pads last done? Front or rear? Was that with new discs? When was the fluid changed?
Autoteca is a car maintenance log for iPhone that keeps those answers in one place. You log brake pads, discs and fluid as services, with the odometer reading attached and a photo of the receipt, and Autoteca reads the date and total from the receipt for you to confirm. A brake fluid reminder is just a date rule of two or three years. Pad reminders can be set by distance, and they use your real odometer history to estimate when the job is actually due rather than counting down a fixed interval.
What it does not do:
- It does not measure pads. Ask the workshop for the figure in millimetres and add it as a note on the service entry. A few of those make a wear trend you can actually use
- It does not diagnose noises. A grinding brake needs a person and a lift, not an app
- It does not read your car's wear sensor. If the warning light comes on, believe it
If you are also checking tyres while the wheels are off, the tyre replacement guide covers tread depth, age and wear patterns.
The Short Version
- New pads have around 10 to 12 mm of material. Plan to replace at about 3 mm, and treat 2 mm as the limit
- A consistent squeal under braking is often the built in wear indicator. Grinding usually means metal on metal
- Vibration points to discs, pulling points to calipers or tyres, and a soft pedal points to fluid or a leak
- Front pads wear faster than rear. Typical life ranges from 25,000 to 70,000 miles, and your own measurements beat any average
- Change brake fluid every two to three years, even on low mileage cars
- Electric cars wear pads slowly but still need inspections, because unused brakes can rust and stick