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Gauging the Air Pressure of Tires Is Getting Easier


Americans could save 100,000 barrels of oil every day if they kept adequate air pressure in their tires, according to federal government estimates.

But such platitudes from Washington have never induced Americans to action, particularly if it involves a chore like kneeling down with an air pressure gauge in hand. Judging from the mail I receive from readers, most motorists don't even own a pressure gauge.

Aside from the improvement in fuel economy, tires last longer and braking systems work more effectively when tires are properly inflated. A tire that is under-inflated by 3 pounds or more begins to lose its longevity.

General Motors plans to introduce a built-in tire gauge that would alert drivers through a dashboard warning light if a tire drops below minimum recommended pressure.

The system works when an implanted sensor with a piezoelectric generator on the inside of the wheel sends a radio signal to a receiver in the dashboard.

The device will be offered first on luxury cars and eventually on other GM cars, a company spokesman said. The cost has not been determined.

In the meantime, there are alternatives. Alert Industries, a Southern California manufacturer, makes a miniature pressure gauge that attaches to the tire stem.

To check the pressure, you need only push a button and take a reading. The gauges, which extend about an inch on the tire stem, are supposed to be accurate to within two pounds per square inch, according to Alert vice president John J. Gillotti.

I tried them and found them to be accurate and easy to install. One potential problem is they release a small amount of air while you push the button and take the reading.

Gillotti said about three pounds of pressure would be lost after 50 checks. That is based on keeping the button depressed for one second. I found it took me at least two seconds to take a reading.

So, my estimate is you would lose about a pound every eight times you check your pressure, a minor loss.

Unlike other devices on the market, the Alert system does not provide continuous monitoring of air pressure.

Other manufacturers offer gauges that screw on the tire stem with a red flag or button that pops out when the pressure drops below a certain level.

The appeal is that you can visually check the tires more quickly than with the Alert devices. But, engineers at a major tire manufacturer say their tests indicate the devices leak excessive amounts of air.

With these gauges, the valve on the tire stem is open continuously, which assures some loss of air pressure. The GM spokesman said the devices, which have been offered by GM on some of its cars, are "not the best."

Alert Industries gauges are sold at some discount stores or direct by calling (800) 356-7913. They are listed for $8.95, but sell for $6 at some stores.

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