One-half of all passenger cars on the road today may have seriously underinflated tires according to a recent sur­vey, a situation that costs car owners, as well as fleets, in terms of tire wear and fuel economy.

"A tire that is underinflated from four to 12 pounds per square inch (psi) could lose from 10 to 40-percent of its life expectancy, depending upon service conditions," said Richard A. Trafas, vice president of marketing services for the B.F. Goodrich Tire Division. The division found that "55.3-percent of all passenger cars checked have at least one tire that is underinflated by four psi or more. This rep­resents a serious condition in terms of both safety and potential economic loss to the automobile owner," Trafas said.

In addition to premature tire wear, underinflation also poses a safety hazard according to Trafas. "Underinflation causes increased sidewall and tread flexing. This leads to high operating temperatures and could result in tire failure."

Checking tire inflation pressure monthly should be an integral part of any fleet maintenance program. Trafas rec­ommends that the pressure be checked daily on cars driven long distances. With increasing operating costs due in part to rising gasoline prices, proper tire inflation can keep some of those costs in check.

"Underinflated tires waste fuel," Trafas said. "The cost of the extra fuel alone could add up to several hundred dol­lars over the life of the car."

Those savings, multiplied by the number of units in a fleet, can add up to substantial savings for fleet adminis­trators.

Of the 1,620 tires checked in the survey, 503 or 31-per­cent were underinflated by four psi or more below the recommended level. On the other end of the scale, 13.1-percent or only 216 tires were seriously overinflated.

The 11-city canvass checked a total of 405 vehicles, with 224 of them having one or more tires in the seriously underinflated category. St. Louis had the lowest average of automobiles with underinflated tires, 23-percent, while Detroit, the Motor City, finished a close second with 24-percent. Atlanta, and ironically, Akron, the tire city, tied for last place with an average of 43-percent of all passenger cars having underinflated tires. Other cities in the survey were Chicago, Los Angeles, Philadelphia, Washington DC, San Diego, Santa Monica and Newport Beach, California.