Many people think those are retreads, but if you look carefully, you'll see wire strands coming from the rubber. That's a sign that the carcass failed, not the tread layer. Using retreads on all positions is safe, legal, and very economical, but whether virgin rubber or retread, air pressure is critical to operating economy and tire life.

Gauging for pressure

Large commercial vehicles are not yet included under the Transportation Recall Efficiency, Accountability and Documentation (TREAD) Act, so the U.S. Department of Transportation urges gauging tires during pre-trip inspections. That could take 15 minutes, so most drivers opt to “thump” their tires to detect if one is low.

Unfortunately, tests have demonstrated that above 65 psi, it is almost impossible to tell if a tire is low just by sound. Shop personnel should gauge tires if drivers won't do it. One reason large fleets have far fewer tires with low pressure is because dedicated yard and shop personnel gauge tires regularly.

There are devices to check and maintain tire pressure. Dana's Road-ranger Central Tire Inflation System (CTIS) is a variation of a system our military uses. Pressure can be raised or lowered to meet conditions: low pressure for low speed; high flotation such as a muddy jobsite; normal for street use; high for highways when fully loaded.

Air pressure monitors from Doran, Tire Stamp, and others have sensors that are either strapped to the wheel or in the valve cap. They transmit to dashboard-mounted displays and alert drivers when pressure is lost.

When gauging tires, it's important to have a calibrated tire gauge. A gauge can be off by as much as 10% to 20% if dropped or handled carelessly. You can take your gauges to your tire dealer (if they don't have a way to calibrate gauges, find another dealer) or buy a calibration machine for your shop.

With a fleet of 10 trucks or more, a $200 unit from ValvePal will pay for itself in less than a year. Its Gauge Testing Station is pressurized with shop air. Then the regulated output is zeroed electronically. Accuracy is within 1.5%.

As Harvey Brodsky, director of the Tire Retreader Information Bureau likes to quip: “In real estate, it's location, location, location. With tires, it's inflation, inflation, inflation.”

— Paul Abelson is a former director of the Technology and Maintenance Council of the American Trucking Association. E-mailtruckwriter@anet.com.