Many cars today have aluminum wheels with openings through which you can see the disc brake rotors and calipers inside. You may have noticed that, if it rained overnight, when you came out to the car in the morning, there was a thin layer of rust on the brake discs. Morning dew can do the same thing to the discs.

This is generally not a significant problem. You’ll get in the car and start driving. The first time you hit the brake, you’re liable to hear a scraping sound. That’s the sound of your brake pads rubbing the rust off your discs. But, if the car is left unattended for too long, the rust may take root and represent a real issue.

With the coronavirus lockdown, it’s just possible that your car has spent more time sitting unused than usual. We’ve also had quite a bit of rain over that period of isolating at home. If you haven’t gotten out in the car for a while, the rust may have penetrated deeper into the metal.

Brake discs have prescribed levels of thickness. Once they wear down below this allowance, safe operation requires replacement. As the brake disc thins, it heats up faster. This can cause issues with stopping as the disc and pads become hotter and hotter. If the rotors have too much rust, even if the pads grind the rust away, over time, too much of the disc may come away as rust.

Disc brake rotors are also checked for ‘run out.’ Run out refers to the amount of wobble in something as it rotates. When disc brake rotors rust, the potential for greater ‘run out’ increases. When a brake disc has too much ‘run out,’ you’re liable to feel the wobble in the steering wheel.

While the brake pads will usually clean away the rust, the process isn’t healthy for the pads, either. They are wearing down quicker, too.

The solution is to drive the car with enough frequency, even if just taking it around the block so that the rust can’t take hold and ruin your brakes. With the lockdown, your brakes may have already suffered irreparable damage from rust. If you think that is possible, you should probably have your brakes checked by a qualified auto repair shop.