QDear Tom and Ray:

The owner's manual for my 2000 BMW 328i says in the interests of safety and handling, I should not rotate my tires. And it implies that tire rotation will not extend the life of the tires in a meaningful way. To rotate, or not to rotate? -- Larry

ATOM: We've always felt that tire rotation is of marginal value in terms of saving you money. Why? Because the cost of tire rotation roughly equals the amount you'd save by extending your tire life. So, our feeling is that if the rotation is free, do it. In other words, if you're having your brakes checked, and the wheels are already off the car and your mechanic is nice enough to put them back on different wheels for nothing, then do it. That's what we do for our customers.

RAY: Actually, we just get confused, and don't remember where the wheels came from. So we tell our customers, "We think we rotated your tires."

TOM: But if you have to pay for tire rotation as a separate service, it's pretty much a wash, as far as we can tell.

RAY: As for BMW, it figures that anyone who buys a BMW places handling above a few bucks. And in many cases, its cars come with directional tires, which are only supposed to be rotated front to back.

TOM: BMW cites safety because the front and rear tires develop different wear patterns. And for at least a little while -- until the wear evens out -- you may have slightly inferior handling. Still, we see nothing wrong with rotating your tires. No harm will be done, in our opinion. But if you're paying your BMW mechanic $125 an hour to move your tires around (and eight bucks a wheel for rebalancing, too), it's very unlikely you'll save any money in the long run, Larry.

Dear Tom and Ray:

I have a 2000 Mitsubishi Galant with only 7,000 miles on it. I have recently noticed that the steering wheel vibrates even when the car is sitting at a stoplight. I took it to the dealer, and he said the vibration is normal. Any thoughts? -- Bob

RAY: It could be normal, Bob. This is not an uncommon problem. And it's not just Galants. We see this on four-cylinder Toyota Camrys, too.

TOM: I'm assuming you have the four-cylinder engine. A lot of four-cylinder engines vibrate in drive when you're stopped at a light. The reason is that by design, it's not as smooth as a six- or eight-cylinder engine.

RAY: Four-cylinder engines vibrate because they produce fewer explosions per turn of the engine's crankshaft. So, with the explosions spaced farther apart, you tend to be aware of the spaces between them.

RAY: I'm assuming that the vibration is only noticeable when the car is under load (when it's in gear) and the engine is running at idle speed.

TOM: My suggestion would be to ask the dealer if he has a 2000 Galant on the lot that he can let you drive. If it vibrates the same way, then you might be out of luck. But if it's better than yours, you can then ask your dealer to do something.

RAY: What he can do is check or even replace your motor mounts. The motor mounts hold the engine in place, and they're supposed to absorb some of the vibration. One of your motor mounts might be broken or cracked.

TOM: He can also try adjusting your curb idle speed just a bit. Sometimes by moving the idle speed just 50 rpm in either direction, you can get the vibration to go away.

RAY: And if none of that works, try to think of it as your very own "magic fingers" machine.

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(c)2004 by Tom and Ray Magliozzi

and Doug Berman