Our reader was horrified when he took his Audi A5 into a dealer and it said he needed replacement brake pads. It then revealed that his brake pads had 10mm of wear left on them, prompting him to get in touch.
What is the legal minimum for brake pads?
As with tyres, there is a legal minimum thickness for brake pads. This is 1.5mm. However, expert advice is that you should replace the pads when they have around 3mm of material left on them.
How do you check your brake pads?
First you need to understand how brakes work. Brakes consist of a disc that rotates with the wheel. There is then a calliper enveloping the disc with a brake pad on either side. Pressing the brake pedal causes hydraulic pressure to force the pads against the discs.
This means that through the spokes of the car’s wheels you might be able to see the pads on the outer side of the disc.
But to make a proper assessment you need to take the wheel off. Haynes recommends you jack the car up, put axle stands underneath for safety and then remove the front wheel. This enables you to see both sides of the pad as they grip the disc.
Haynes points out that to check pads fully, you must remove the pads, clean them and then measure them. But that is beyond most drivers who have neither the tools nor the time.
And they are quite thin…
Can you tell the difference between 1.5mm and 3mm? Thought not. That’s why you can buy specialist tools that measure the thickness of brake pads. Some tools even claim to measure brake pad thickness without you having to remove the vehicle’s wheels.
If brand new brake pads are about 10mm thick. When they are down to the legal minimum, 85% of them will have worn away.
Do car makers have company standards?
Yes they do and it’s information they protect closely. However, we think this Audi dealer is probably either mistaken or taking things a bit far if it’s suggesting brake pads with 10mm of material on them need replacing.
How do you know if your brake pads need changing?
We’ve done a fuller blog on this here. But there are some giveaways. First, a warning light should come on to tell you that your brake pads need attention.
If you ignore that, you will hear a tell-tale grinding noise when you brake. This is from the metal backing material of the brake pads rubbing against the metal of the disc. And metal on metal is never a good sound. There will also be a vibration through the pedal.
Then there’s mileage. Brake pads last anywhere between 25,000 and 60,000 miles depending on the car and the kind of driving. It can also depend on the pads used: cheap aftermarket ones probably won’t do as many miles as pukka manufacturer-sourced ones.
I’ve been writing about cars and motoring for more than 25 years. My career started on a long-departed classic car weekly magazine called AutoClassic. I’ve since pitched up at Autosport, Auto Express, the News of the World, Sunday Times and most recently the Daily Telegraph. When I’m not writing about cars and motoring, I’m probably doing some kind of sport or working in my garden.