Measuring brake pad thickness is the most reliable way to decide when to replace them.
Brake Pad Thickness Chart
10-12 mm: New pads. 6-8 mm: Still good. 4-6 mm: Start planning replacement. 3 mm: Replace soon. 2 mm or less: Replace immediately.
How to Measure
Brake pads start with 10 to 12 mm of friction material bonded to a metal backing plate. You can measure the thickness by looking through the wheel spokes. The outer pad is visible at the caliper. For a more accurate measurement, remove the wheel and use a ruler or caliper. Measure only the friction material, not the backing plate.
Minimum Thickness
Most manufacturers recommend replacing brake pads when the friction material reaches 3 mm. At this point, the pad is too thin to dissipate heat properly. The stopping distance increases and the risk of damaging the rotor goes up. If the pad is 2 mm or less, the metal backing plate may contact the rotor directly. This causes grinding noise, deep grooves, and expensive rotor replacement.
Front vs Rear
Check front pads more often than rear pads. Front pads wear faster because they handle most of the braking force. Rear pads typically last longer, but they should still be inspected at every brake service. If one pad on an axle is significantly thinner than the other, the caliper may be sticking and needs inspection.
