How to Check Brake Pad Thickness
- Park on level ground and let the brakes cool. Set the parking brake. Rotors get hot enough to burn skin after a drive.
- Look through the wheel spokes. Find the caliper, the clamp that sits over the shiny metal disc (the rotor). A flashlight helps.
- Find the pad. It is the flat block pressed against the rotor inside the caliper.
- Judge the friction material. That is the layer between the metal backing plate and the rotor. New pads have about 10 to 12 mm (about 1/2 inch). Plan a replacement around 4 mm, and replace right away at 3 mm (about 1/8 inch) or less.
- Check both sides of the car. Pads can wear unevenly, and the inner pad you often can't see may wear faster than the outer one.
If the wheel design blocks your view or the inner pad is hidden, a mechanic can measure both pads with the wheel off.
Listen: Squealing vs. Grinding
- Squeal when you brake: many pads have a small metal wear indicator that squeals when the pad is nearly worn. Book a replacement soon.
- Grinding: the pad material is gone and the metal backing plate is cutting into the rotor. Stop driving as soon as you safely can.
- Squeak only on the first stops of the day or in the rain: usually surface rust or dust that clears after a few stops.
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Feel: What the Pedal and Steering Tell You
- Pulsing pedal or a shaking steering wheel when braking: usually the rotors, worn to an uneven thickness.
- The car pulls to one side: often a sticking caliper or pads wearing unevenly.
- Soft or spongy pedal, or it sinks toward the floor: air or moisture in the brake fluid, a leak, or a hydraulic problem. This is not normal pad wear. Stop driving and have it inspected.
- Longer stopping distances: worn pads, worn rotors, or old brake fluid can all add distance.
Dashboard Brake Warning Lights
A red BRAKE light means the parking brake is on, the brake fluid is low, or there is a hydraulic problem. Brake fluid drops slightly as pads wear, so a low level can mean very worn pads or a leak. Some cars also have a separate pad-wear light. An amber ABS light means an anti-lock system fault: normal braking usually still works, but have it checked soon.
Pads or Rotors? A Symptom Guide
Use this as a starting point. A measurement with the wheel off is the only way to be sure.
| Symptom | Likely cause | What usually fixes it |
|---|---|---|
| High-pitched squeal when braking | Pads down to the wear indicator | New pads |
| Grinding | Pads worn to the metal backing plate | New pads and rotors |
| Pulsing pedal or shaking wheel | Uneven rotor thickness | New rotors and pads |
| Pulls to one side | Sticking caliper or uneven pad wear | Caliper service, possibly pads |
| Soft or spongy pedal | Air, moisture, or a leak in the brake fluid system | Fluid service or leak repair |
| Deep grooves or a raised lip on the rotor edge | Worn rotor | New rotors |
Ceramic vs. Semi-Metallic vs. Organic Brake Pads
| Pad type | Best for | Trade-offs |
|---|---|---|
| Ceramic | Most cars and SUVs, daily driving | Quiet, low dust, long life; costs more |
| Semi-metallic | Heavy trucks, towing, hard use | Handles heat well; noisier, more dust, more rotor wear |
| Organic (NAO) | Light, older cars | Quiet and cheap; wears fastest |
"Performance" pads are usually a ceramic or semi-metallic compound built to handle more heat. On a daily driver, the pad type the factory specifies is the right choice. We install ceramic pads on most cars and SUVs, and semi-metallic where the factory specifies them, such as heavy trucks and vehicles that tow.
When to Call a Mechanic
If you measure 4 mm or less, hear grinding, or feel a pulsing or soft pedal, it's time. We come to your driveway, measure the pads and rotors on both axles, and give you a written quote before any work starts. See mobile brake repair in San Antonio for pricing and booking.
Grinding or a soft pedal means the car should not keep being driven. We can fix the brakes where the car is parked.
About the Author
Danny Cisneros
Danny is the owner and lead technician at Lowered Standards. With 10+ years of hands-on automotive repair experience in San Antonio, he performs every job personally. All work is backed by a 12-month / 12,000-mile warranty on parts and labor.
(210) 570-9220Frequently Asked Questions
Every oil change is a good habit, or about every six months. Check sooner if you hear squealing or grinding, feel pulsing, or often tow or drive steep hills.
New pads have about 10 to 12 mm of friction material. Plan a replacement around 4 mm, and replace them at 3 mm or less.
Yes, if the rotors are still above the minimum thickness and are not scored or warped. A mechanic measures the rotors to decide. Grinding almost always means the rotors need replacing too.
For most daily drivers, yes: they are quieter, cleaner, and last longer. Semi-metallic pads handle heat better, so they suit heavy trucks, towing, and vehicles where the factory specifies them.
