If your wheels consistently look black and dirty, then it's likely that you are suffering from a problem of excessive brake dust. Regular usage of your brakes wears the pad friction material down, which creates small particles of dust that stick to nearby surfaces. Excessive brake dust looks ugly and can potentially lead to paint damage when allowed to build up for too long.
Recognizing the Problem
All cars generate some amount of brake dust, so it can be tricky to know how much is too much. In general, watch out for these symptoms that may indicate your car is producing a more than reasonable amount of dust:
If you are concerned about the amount of dust your brake pads generate, then give your wheels a thorough cleaning and observe them for a few weeks. Rapid dust accumulation (especially on one wheel) likely indicates an underlying issue.
Understanding the Underlying Cause
Brake dust always has one underlying cause: wear on the brake pads. When your brakes generate too much dust, it generally points to pads that are wearing too rapidly. In some cases, the problem may be the pad material itself. Certain friction materials produce more dust or result in particles that are "stickier" and remain bonded to the wheels.
The typical reason for brake pads to wear quickly is excess contact between your brake pads and brake rotors. This extra contact can occur because the caliper pistons are not retracting correctly, either due to an issue with the caliper or the master brake cylinder. A faulty brake hose can also prevent the caliper piston from fully retracting.
Reducing Your Brake Dust
If your pads are producing excess brake dust due to sticking calipers, then a professional brake shop will need to diagnose the issue further. While a stuck caliper on its own is not immediately dangerous, issues with your brake hydraulics can progress and create more severe problems. A stuck caliper can also create uneven braking and cause extreme and premature wear to your pads and rotors.
When your pads generate excess dust even when operating normally, your only option is to switch to lower-dust pads. Ceramic pads generally produce significantly less dust than other options while still offering good stopping power. Switching to ceramic pads when your old pads wear out should substantially reduce the amount of dust build-up on your wheels.
To learn more, contact a brake repair shop.