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Car Talk Columns

June 1997


Dear Tom and Ray:

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I constantly get zapped when I get out of my cars when the humidity is low. Is there any way of stopping this short of dragging a chain from my undercarriage like the old fuel trucks used to do (yeah, I'm that old!)? In the dead of winter, I have actually sparked a 2-inch lightning bolt, enough to light up the neighborhood. -- Charlie

Tom: C'mon, Charlie, what kind of man are you? What's a few hundred volts of electricity between and man and his car every now and then?

Ray: Actually, there are several things that exacerbate static electricity problems in cars, Charlie. One is the relative humidity. When the air is very dry -- like in the winter -- static electricity is worse.

Tom: The second factor is tires. Tires play a crucial role in discharging the static electricity that builds up while you drive. And lots of newer "low rolling resistance" tires are poorer at discharging static than older tires that used more of a substance called "carbon black."

Ray: The final factor is sartorial, Charlie: those polyester leisure suits you wear. And we know you're of the generation that wears them because you're old enough to remember fuel trucks dragging chains!

Tom: OK, well, let's assume for the moment that you're a man of the '90s and you go light on the polyester. And let's assume you have no personal influence over relative humidity.

Ray: So the only thing you can really influence is how well your car discharges the static electricity. So you can either go to "higher rolling resistance" tires, which is impractical because tires are expensive and because increasing your rolling resistance will reduce your gas mileage. Or you can find another way to discharge the "charge."

Tom: You have three options here. One is to discharge it yourself while exiting the car. If you hold your key and touch the end of it to some metal part of the car, the built-up charge should jump from the end of the key to the car, "hurting" the end of the key and not your finger. The downside is that you do have to remember to do this, and you look kind of stupid cringing wearily while poking your key all over your car as you get out.

Ray: The second option is a pair of rubber grounding strips that you hang off your undercarriage. You can buy these at auto parts stores. They have a metal wire embedded in the rubber, and they hang down and discharge the static as it builds up. And they work pretty well. The only downside is they tend to be real cheap junk, and they wear out every six months or so and need to be replaced.

Tom: Your final option is to hang a chain under the car, like the old fuel trucks did. That's certainly the cheapest solution. And while most people would find that intolerably noisy, we figure at your age, Charlie, you might not even hear it!


In their pamphlet "Should I Buy, Lease, or Steal My Next Car?" Tom and Ray break down the strategies for buying a car, so you can make the most of your money. To order, send (check or money order) to Ruin, P.O. Box 536475, Orlando, FL 32853-6475. You can also order online.


© 1997 by Tom and Ray Magliozzi and Doug Berman Distributed by King Features Syndicate, Inc.

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