Gone is the heat of summer, replaced by cool nights and mornings. Soon, many areas of the country will be faced with consistently chilly, even sub-freezing temperatures.

This time of year serves as a reminder that a drop in tire inflation pressures corresponds with the falling thermometer readings. Goodyear experts explain that air pressure in a tire typically goes down 1-2 pounds for every 10 degrees of temperature change.

"Odds are that many motorists haven't checked their tire pressure since the weather began turning colder. If the last time the tire pressure was checked was during the heat of summer, with temperatures around 80 or 90 degrees, many people could be riding on severely underinflated tires without realizing it," said Joey Viselli, Goodyear brand director.

Maintaining proper air pressure is the single most important thing drivers can do for their tires. Underinflation is the worst enemy a tire can have, as it causes increased treadwear on the shoulder area (outside edges) of the tire. It also can reduce fuel economy by increasing rolling resistance -- since soft tires make the vehicle work harder.

Goodyear suggests checking tire inflation at least once per month with a reliable gauge. To find the proper air pressure for a tire, look in the vehicle owner's manual, in the glove box or on the driver's side door jamb. Hint: The inflation pressure stamped on the sidewall of a tire is the "maximum" pressure, not the "recommended" pressure.

"Even though consumers can simply and quickly check the air pressure of their tires, it becomes a neglected practice by many," Viselli said. "That's too bad, because the four patches of rubber that come in contact with the road surface are important to the performance of the vehicle. They are keys for acceleration, lateral traction and braking grip."

For consumers who don't want to bother with regular tire pressure checks, Goodyear offers a "Free Air" campaign. Motorists can have their tires -- regardless of brand or where they were bought -- inspected for free at any of the 650 Goodyear-owned stores, and at participating independently owned and operated locations across the country.

The increasing usage of in-dash tire pressure monitor systems on new vehicles will likely help more consumers to pay attention to their tires' pressure levels. Still, Viselli urges the old-fashioned method of checking tire inflation.

"At least once a month, take a few minutes and check your tire pressure with an accurate tire gauge. You can't tell if a tire needs air just by looking. It could be underinflated by 10 pounds and still look fine," he said.

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