Opinion: Neglected Tires, Deflated Reputation

This Opinion appears in the Nov. 4 print edition of Transport Topics. Click here to subscribe today.

By Al Cohn

Director, New Market Development

and Engineering Support

Pressure Systems International

Excessive roadside service calls are a major symptom of a dysfunctional fleet operation, the sort whose pickup-and-delivery times are less than dependable and whose truck downtime is costing the head office big bucks for lost business and expensive repairs. And the No. 1 cause of roadside service calls is tires.

It shouldn’t be news to anyone that tires play an oversize role in how long a fleet truck spends pulled over to the side of the road. After all, there are 18 tires on a typical Class 8 longhaul tractor-trailer combination, and even the biggest of big rigs isn’t likely to have 18 of any other particular component.

What’s more, the most intense preventive maintenance routine can’t protect tires from eventually running into (or over) trouble or simply wearing out. A number of tire issues can occur during a trip, leading to breakdowns that require roadside service. Specific tire problems that can stop a vehicle along its route include:

• Tread-area punctures.

• Excessive heat caused by loss of pressure and causing the tire ultimately to fail.

• Sidewall damage/snags.

Tread-area punctures are the leading cause of a tire losing air, but the loss generally is gradual. It may take a few days for the tire to lose enough air pressure for its sidewall to begin the excessive flexing that generates heat buildup. Heat is a tire’s worst enemy, and any pressure loss will accelerate that.

When a tire continues to generate excessive heat, the rubber slowly breaks down, eventually leading to failure.

Sidewall damage to tires happens far more frequently on the right side — or curb side — of trailers than to any other wheel position. It’s also more of a problem for new drivers than for experienced pros.

In addition to tire failure, inspectors at roadside stations target tires as a top line item to check when a vehicle comes through their station. They are looking for tires with tread depth below the minimum 4/32 inches for steers and 2/32 inches for drives, trailers and dollies.

Inspectors also are looking for exposed belts and/or fabric along with flat tires. By definition, a tire is flat when the measured air pressure is 50% or less of the maximum tire pressure molded onto the tire sidewall.

If any of these conditions is present, the vehicle is flagged “out of service,” and a roadside service call is the only way to get the rig back on the road.

Roadside service costs fleets money and has a dampening effect on a carrier’s reputation for on-time deliveries. If a tractor-trailer — and more to the point, its cargo — is just sitting there off the road, it isn’t making money. And it certainly isn’t getting its load any closer to the scheduled destination.

Given that the average downtime for roadside service is 2.5 hours, the result is a disappointed shipper and the probability of late-delivery penalties.

More to the point, what’s at stake isn’t just the time a service call requires — it’s a fleet’s overall success as the carrier of choice for a particular shipper.

It’s a major black mark to be cited for any of these conditions, which should have been caught during pre-trip inspections and resolved before the truck ever left home.

Drivers must be trained to inspect tires visually, take tread-depth measurements and even measure the tire pressure routinely.

Visual tire inspections should include running a hand over the tread and sidewall to check for signs of irregular wear and punctures. If a tire is close to the legal tread depth, a tread-depth gauge measurement is strongly suggested. The gauge itself needs to be checked to make sure it measures zero on a flat. You also need to be sure not to take the measurement at a tread-wear indicator location or on top of a stone ejector located at the bottom of the many grooves — that could put you off by as much as 3/32 inch.

Measuring the air pressure in tires using a calibrated pressure gauge is critical — air is what carries the load, and tires with low pressure will result in excessive heat and premature tire removal. Driving with lower pressure than recommended in tires not only causes premature failures and expensive roadside service calls,it also reduces fuel efficiency as the tire’s footprint becomes larger.

Tire gauges are simple devices, but they can lose accuracy quickly. Because of these problems, automatic tire-inflation systems and tire-pressure monitoring systems can play a major role in a serious tire program.

Obviously, drivers play a major role in any good tire-

maintenance program. By accepting responsibility for paying attention to tire conditions — and making sure problems are resolved — drivers make a serious commitment to your fleet’s well-being and its ability to make good on promises to your customers.

Pressure Systems International, based in San Antonio, sells automatic tire-inflation systems. The author also is chairman of the Cleveland Chapter of SAE International.