QDear Tom and Ray:

I have a 2000 Toyota Camry LE with 48,000 miles on it. Last week, I had the front brakes replaced at a Toyota dealership. I was driving on a busy freeway in Michigan today, when everyone in the right lane stopped suddenly. I, too, slammed on the brakes, and my car swerved back and forth and spun around into oncoming traffic. A truck heading right for me hit me on the front driver's side, but luckily I walked away without a scratch. Why did the car swerve when I slammed on the brakes? I don't have anti-locks and the road was dry.

-- Carrie

ARAY: Few things are more frightening than sliding backward and looking straight at people who were behind you.

TOM: But my guess is that the brake job had little or nothing to do with you spinning around. Here's my guess: Since you don't have an anti-lock braking system, your brakes locked up and your car started to skid, with the back end coming around.

RAY: You then tried to correct and steer into the skid. But, like most people who don't skid a lot, you overcorrected. That sent the back end the other way. You overcorrected again, repeating this process, each correction getting bigger with the momentum of the car, until you spun all the way around.

TOM: So you are a walking, breathing advertisement for anti-lock brakes. By preventing the brakes from locking up, ABS allows you to keep steering the car during an emergency stop.

RAY: It is possible that your recent brake service played some role. If the mechanic just replaced your pads and didn't machine your discs, that might have caused the brakes to pull when you slammed them on. Sometimes disc brakes pull in one direction until the pads properly seat to the discs.

TOM: But there's nothing the brake guys could have done to cause the car to swerve back and forth. That had to be your reaction to the skid.

RAY: What you might want to do is go to a wet or snowy parking lot some Sunday morning before the stores open and practice putting your car into a skid with no traffic or other obstacles around.

TOM: And next time, get the ABS.

Dear Tom and Ray:

The wheels on our 2003 Chevy Tahoe Z71 are 17-inchers. But the spare has a 16-inch wheel. Neither the salespeople nor the manufacturer can tell us why. My husband and I are hoping you can find an answer.

-- Martha

TOM: C'mon, Martha. You've seen one wheel, you've seen 'em all. What difference does an extra inch make?

RAY: GM tells us that although the spare wheel is an inch smaller in diameter, the tire is bigger. So the wheel-and-tire combinations are the same size. They have the same outer circumference, so they all travel the same distance per revolution of the axle. Therefore, no damage is done if you drive with the spare tire installed.

TOM: GM says there are two reasons for providing a 16-inch steel wheel as a spare. One is that some 17-inch wheels are hard to fit in the spare-tire storage space.

RAY: But if the overall wheel-and-tire combination is the same size, what difference could that make?

TOM: I'd have to guess it has to do with the shape of the spare-tire well. Since it was originally designed for 16-inch wheels, maybe the wheel itself is difficult to secure if it's bigger than 16 inches, even if there's enough room for a bigger tire.

RAY: The other reason GM gives is that the 16-inch spare is a steel wheel, while the 17-inchers are aluminum alloy -- and a steel wheel is less likely to receive cosmetic damage while under the car.

TOM: And a steel wheel is cheaper.

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(c)2002 by Tom and Ray Magliozzi

and Doug Berman