U.S. drivers will pay the highest fuel prices on record this Memorial Day weekend, and inflation is playing a big role at the pump.

The air pump, that is. Tires' importance at the gas pump also is growing as gas prices climb, according to Bill Egan, chief engineer of product design for Goodyear.

Average U.S. retail gasoline prices jumped by 3.4 cents last week to $1.526 a gallon, according to the U.S. Energy Department. The pump price is up 40 cents a gallon from a year ago.

Running a tire 20 percent under-inflated -- only 4 to 5 pounds per square inch -- increases fuel consumption by a whopping 10 percent, Egan said. Tread life is reduced by 15 percent.

If that's not enough, the Society of Automotive Engineers reports that 87 percent of all flat tires have a history of under-inflation.

In 1995, the Energy Department said underinflated tires wasted an estimated 4 million gallons of gas daily in America. "At today's prices and with more vehicles on the road, that's a huge expense," Egan said. "An under- inflated tire deflects more energy and increases rolling resistance, which robs the vehicle of fuel efficiency."

The escalating gasoline prices mirror the severity of tire under- inflation, Egan added. In the 1970s, the National Highway Traffic Safety Administration claimed that half the nation's cars had underinflated tires.

Other studies stated that 25 to 28 percent had at least one tire "seriously underinflated" (4 psi or more below manufacturer's recommendation).

Goodyear conducted its own parking lot survey, sampling 250 vehicles or 1,000 tires. More than 28 percent of the vehicles had one or more low-on-air tires.

Goodyear recommends that motorists should check tire inflation monthly or before a long trip. Tires should be inflated to the vehicle manufacturer's recommendations printed on the vehicle's door placard or in the owner's manual, not the maximum limit stamped on a tire sidewall, Egan said.

An estimated 34.4 million Americans will travel over the weekend, making this the busiest Memorial Day weekend on record, and up more than 3 percent from last year, according to the AAA.

The wary eye on tires may lead to better consumer understanding. For example, consumers may choose to replace worn tires with the tires that came on their new vehicle. Egan said most original-equipment tires are optimized for low-rolling resistance, which converts into improved fuel economy.

Fuel-efficient tires are only part of the solution, however. Proper tire inflation is paramount to saving money at the gas pump. An under-inflated energy-efficient tire defeats the purpose in saving fuel, he said.

The Organization of Petroleum Exporting Countries is expected to meet June 21 in Vienna to discuss oil production. In March, OPEC members agreed to increase production by 1.7 million barrels a day, but that didn't go far enough to ease U.S. gas prices.

Egan said consumers may control their own destinies - with tire care. If just half of the 28 percent of motorists who regularly ignore tire inflation begin monthly maintenance, the gas shortfall and resulting price increases may be kept in check.