Automotive brake technicians gauge the lifespan of brake pads by measuring the thickness of the pad material. Most pads begin with 5 to 7 mm of pad and require replacement when they fall below 3 mm. You don't need factory training in order to check the thickness of the brake pads on your vehicle. Even if you never plan on performing a brake job, it is good to know how to check the thickness of brake pads so you have a better understanding when speaking with a mechanic. Anyone with minimal mechanical aptitude can do this.
Access the brake pad by either looking through your wheel or removing the wheel from the vehicle if it does not provide enough clearance to properly see the pads. Remove the wheel by loosening the lug nuts with a lug wrench. Lift the vehicle with the floor jack and support it on the jack stand before taking the lug nuts and wheel off by hand.
Hold the thin metal ruler or the tire tread depth gauge against the side of the brake pad and note the thickness. Make sure to measure only the pad and not the steel backing plate.
Repeat step two in two other places on the brake pad to make sure you have an accurate measurement. Some pads have beveled leading and trailing edges, which can give a false sense of the pad's true thickness.
