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Road Gator Wrestling

Why summer roads are littered with tire treads and how to avoid them

by Mac Demere
DriveSmart - Driving - autoMedia.com

Starting in mid-May, those who drive Sunbelt roads begin seeing the occasional 18-wheeler truck tire tread lying beside or on the highway. Some call them "road gators." We presume that's because they'll take a bite out of your car if you run over one. Hit a road gator that's lying on its side and it'll slice open the engine or transmission oil pan, rip off a brake or fuel line or snap off a suspension component.

Gator Season

By June and July, the phenomenon creeps northward. In mid-summer, you can find road gators as far north as Interstate 70 or 80. In the Deep South, August is prime road gator birthin' month. Last August, on one the hottest days in Mississippi history, U.S. 78 (which will soon be renamed Interstate 22) was bordered by literally thousands of truck tire treads.

The damage from these "sleeping" highway gators is minor compared to what a gator can do while it's being born. A tread in the process of leaving the tire is a heavy, steel-reinforced band that can easily slice through a nearby vehicle: Another good reason to never cruise alongside a big rig.

If you hear an 18-wheeler tire making a regular whap-whap-whap sound, that's the pre-birth cry of a highway gator. It may take a few minutes or a few days, but a new gator is about to enter the world. They're born full sized and angry.

Behind the Breed

Many mistakenly think that most, if not all, highway gators are failed retreads. My unscientific, but regular studies say that almost none are retreads. Instead, they're what tire engineers call "tread separations." The tire's steel and nylon belts—along with the tread—have broken free of the tire's body or "carcass." Here's how to tell: If the road gator's ends shows frayed steel or fabric, it's a tread separation, not a failed retread.

Car, pickup and SUV tires also fail in the same way and for the same reasons. These smaller gators are less obvious and not as dangerous to other vehicles. But they can be catastrophic to the four-wheeler that loses the tread.

Tread Separations

The most common causes for tread separations—for both big rigs and passenger vehicles—are underinflation and overloading. Both of these create heat that breaks down a tire's internal components. Add in a furnace-like summer southern road and you have the recipe for a catastrophic failure.

Another cause of truck tire tread separations is that some big-rig drivers inappropriately use the dual tires for extended mobility. There's only one reason big rigs have two tires on all positions (except the front axle): So they can carry up to 80,000 pounds. The second tire in a pair is not a backup or spare. If a fully loaded truck doesn't have all 18 tires holding up their share of the load, tires will start failing.

Often big-rig drivers keep on driving even after a tire fails. Sometimes this is because the driver isn't aware of the failure. (I have a Class A Commercial Driver's License: The driver can't feel the tires as in a car.) But often there are other reasons: fulfilling a deadline, reaching a nice motel before his driving time expires, or making it to a good truck stop.

One major shipping company's policy says drivers will be immediately fired if caught driving on a failed tire. "But you'd be surprised how many tires fail just as the truck enters the 'yard'," said a company representative who asked to remain anonymous. Of course, the tire had failed many miles before its home base. But there's probably another company policy that says drivers will get fired if they consistently miss deadlines.

When one truck tire fails, that's only the beginning of the problem. If the driver doesn't stop immediately, the remaining tire of that pair becomes overloaded. In short order this will damage the tire's internal components. Because of the safety margin built into tires, the remaining tire probably won't come apart until after it receives a new mate. But it's like a hand grenade with the pin pulled: It's just a matter of time before it blows. If it's a trailer tire, it may be many months before it fails. The trailer can sit unused or is employed to carry light loads. But the next time that tire experiences a 110-degree day with a legal-limit load aboard, a new road gator will enter the world. If the driver doesn't stop immediately, its mate—the replacement for the original blown tire—will suffer terminal damage. And the cycle will repeat itself.