Sand bags for winter traction?

Dear Car Talk

Dear Car Talk | Dec 01, 1990

Dear Tom and Ray
I am aware that while driving in winter conditions, it is important to keep extra weight in the trunk of a car to help with traction. However, now that I have a car with front wheel drive, this practice seems to be a waste of time. Should I bother putting sand bags in the trunk or not?

TOM: Good question, David. Traction is a complicated issue, and we'll do our best to try to complicate it a little more. The truth is there are three situations in which traction is important; when you're starting, when you're stopping, and when you're moving. Other than that, traction doesn't matter.

RAY: Traction is actually a function of a lot of things; the weather, the condition of the road, the tire tread, the car's suspension, the weight of the car, to name just a few. STARTING traction is most affected by the weight directly over the driven wheels. That's why some people put sand bags in the trunk of their REAR-wheel-drive cars.

TOM: And you're right, David. Sand bags aren't necessary for FRONT wheel drive cars. Those cars already have the weight of the engine and trans??mission over the front wheels.

RAY: But there's an even better reason not to fool with sand bags. Your car's handling has been very carefully engineered. When you add weight to one end or the other, you disrupt that delicate balance. In other words, if you throw sand bags in the trunk of a front wheel drive car, you tilt the front end up, in effect, taking weight OFF the front wheels. Not only do you reduce your starting traction, but by throwing off the balance, you could easily screw up your braking and handling traction too.

TOM: So while extra weight generally improves traction, the only safe place to put it is in between the wheels. That's why, for traction, we suggest car-pooling. In fact, when recruiting car-poolers, you could start by putting up a sign at Weight-Watchers.

RAY: Actually, David, when it comes to winter traction, there's no substitute for four good snow tires. You should throw one bag of sand in the trunk, but not for the added weight. Carry it so when you DO get stuck, you'll be able to sprinkle some sand under the tires and perhaps get free. If not, at least your kids will be able to amuse themselves by building sand castles while you're waiting for the tow truck.

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