Ideal air pressure for driving in snow?

Dear Car Talk

Dear Car Talk | Apr 01, 2002

Dear Tom and Ray:

During a safety meeting at my workplace, we were discussing tires and driving in the snow. Several folks suggested that you could get better traction in the snow by letting some of the air out of your tires. I disagreed, since it seems like this would only increase the likelihood of skidding. I told my crew I'd research this and get back to them. Can you help? -- Danny

RAY: Well, our official position is that you should not mess with tire pressure at all, Danny. And if you won't take our word for it, ask anyone who has rolled over a Ford Explorer.

TOM: Even in theory, it's a tough question to answer, and it depends on what kind of snow you're in. Generally speaking, thinner tires are recommended for most snow conditions. Thinner tires are better able to bite down through the snow and reach the pavement for traction. That would argue for higher tire pressure, which creates a thinner tread patch.

RAY: But if you had snow that was so deep you couldn't cut through it, you might want the widest possible tread footprint, to mimic a snowshoe. That would argue for lower tire pressure.

TOM: Of course, there's no way you'd float a 3,000-pound automobile on top of the snow, but we're just talking theory here.

RAY: But that theory does apply on sand. When you drive on sand, manufacturers suggest that you lower the tire pressure. You'll never cut through the sand, so you want the largest, softest footprint you can get to try to maintain traction on top of the sand.

TOM: So what's the answer, Danny? Leave it alone. We're opposed to playing around with your tire pressure for two reasons: One is that it will hardly make a difference, in terms of snow traction. The tread pattern, the rubber compound and the condition of your tires will play much bigger roles than a few pounds of pressure either way.

RAY: And more importantly, once you get through that situation, you'll then be driving on improperly inflated tires, and that's dangerous.

TOM: So make sure your tire pressure is set at the level recommended by the manufacturer. And put a set of snowshoes in the trunk in case you have to walk to a phone booth and call a tow truck.

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