What's behind the smoke billowing out from my wheel?

Dear Car Talk

Dear Car Talk | Apr 01, 2005

Dear Tom and Ray:

My new Honda Civic did something different today. After a 10-mile drive, I parked the car in my garage, and noticed smelly smoke coming from the rear, passenger-side tire. When I felt the tire, it was not hot, but the wheel WAS very hot, and the smoke seemed to be coming from the holes in the wheel. I felt the other wheels, and the other rear wheel was hot, too, but no smoke there. What could be the problem? Is it dangerous to drive now? -- Dolat

P.S. Please hurry with an answer; I need to go shopping!

RAY: Dolat, I apologize for the delay in responding. I hope you've at least ordered takeout while you've been stranded in your house waiting for our answer these past seven years.

TOM: Actually, we're going to recommend that you take the car back to the dealer and have your brakes checked.

RAY: My guess is that you drove with your parking brake partially applied. Since it's a new car for you, you might have forgotten to release it, or might have released it only partway without knowing it.

TOM: The parking brake applies the rear brakes on this car. And if you drive 10 miles with the brakes partially applied, you'll certainly heat up the brakes enough to make smoke. The danger is that if you heat them even more, you could boil your brake fluid. And if that happens, you won't be able to stop. This is what's known in the medical profession as "a bad outcome."

RAY: Now, before you protest that you would never, ever drive with the parking brake on, another possibility is that you DID release the parking brake, but either the cable or the caliper remained stuck in the "on" position. This seems unlikely, since it's a new car, but you never know.

TOM: A third possibility is that what you saw smoking was just the rust-preventive that they apply to new cars. They want to keep the stuff you can see from rusting until you've owned the car for at least 10 days. So they spray this stuff on the drums, and it quickly wears off -- or in your case, perhaps burns off.

RAY: So first, check to be sure the parking brake is all the way off before you drive away -- make sure you can push it down no farther. Then ask the dealer to take a look at the parking brake and rear brakes, and make sure they get clean bills of health. And then, shop 'til you drop, kiddo.

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