Dear Tom and Ray:

I have a 1998 BMW 528i sports edition -- and only one speeding ticket so far. Shortly before a long road trip, my dealer rotated my tires at a regular service (at about 9,500 miles). Although the car still rode very well, I noticed a slight difference in turning and handling. When I looked at the owner's manual that evening, the manual clearly stated on page 107: "In the interest of safety and optimal vehicle response, we advise against rotating tires. Braking and traction may be adversely affected." I called several BMW dealers. All said they always rotate tires to extend the tread life. So why does BMW recommend against rotating tires as a matter of practice? -- Pat

Ray: The key words in the owner's manual are "optimal vehicle response." And you know how serious the Germans are about optimizing everything, right? They're the ones who refused to provide cup holders to Americans because, "Vee see no reason vy ze driver should desire a beverage. Ze car is zatisfaction enough."

Tom: BMW is right that handling and braking can be affected by rotating the tires. And they've correctly concluded that it would be most noticeable: a) on a precise- handling car like a BMW; and b) by people who are very picky about their cars, like BMW 528i sports edition owners.

Ray: Over time, each tire on the car develops a unique wear pattern based on which corner of the car it's on. So when you switch them, you do -- at least temporarily -- alter the handling.

Tom: Then, after a few hundred miles, the tire wears down to its new position and everything is normal. By the way, that's also why rotated tires last longer. By wearing them down in different areas, rather than wearing them all the way down in one area, you extend their life.

Ray: If you want to minimize the impact on the car's handling, you'd have to rotate the tires frequently, before the wear patterns were firmly established. A spokesman at BMW says that if you're going to rotate the tires, it's best to do it every 3,000 miles. But then, he says, it becomes cost-prohibitive.

Tom: Right. If you spend $25 to rotate the tires every 3,000 miles, and the tires last 48,000 miles instead of 36,000 miles, that extra 12,000 miles will cost you almost $400 bucks in tire-rotation costs!

Ray: And come to think of it, I guess that answers your original question, Pat. "Why do the dealers rotate tires even though BMW recommends against it?"

What's the best way to warm up your engine in the morning? Find out by ordering Tom and Ray's pamphlet "Ten Ways You May Be Ruining Your Car Without Even Knowing It!" To order, send (check or money order) to Ruin, P.O. Box 536475, Orlando, FL 32853-6475. You can also order online.

© 2000 by Tom and Ray Magliozzi and Doug Berman Distributed by King Features Syndicate, Inc.

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