Feature Article: Seven tire killers

John Baxter | May 03, 2010

Failure to seal the inner liner after the tire is punctured will allow moisture to penetrate the casing and rust the steel cords, which causes them to fatigue and break after mileage is accumulated.

6. Improper repairs

A rope repair is a simple way to plug a puncture from the outside, but it often causes air to penetrate the belts, pushing them apart. Merely plugging a hole can also allow moisture from inflation air to get into the cords, and corrode them, creating a catastrophic failure later.

“Besides the danger of running a damaged tire without inspecting the casing, rope repairs cannot withstand the air pressures required by commercial steel cord tires,” says Gudermuth. Plugging a hole in the “no repair zone” of the shoulder is a big no-no, he says. “Quality repairs are a bargain compared to compromising road safety or damaging the vehicle.”

While some forms of tire plugs may be satisfactory just to get you home, the tire must be shortly thereafter removed and inspected, Walenga says. The inner liner must be resealed – from the inside – before it can be considered safe for long-term use or casing re-use during retreading. Gudermuth says, “Even a properly repaired tire must be carefully inspected for damage to the steel casing cords and reinflated by trained service personnel.”

In this zipper failure, the gash is wide and the cords are completely separated. Such a tire can explode and seriously injure the person installing it.

The repair materials must be fresh, Walenga says. Tire sealants, patches and vulcanizing cements must be compatible with one another, so use only materials from the same manufacturer. The tire must undergo a full inspection inside and out, too, or you’ll never be safe or be able to count on retreadability.


7 Tire unsuited for the application

“My bicycle tires do a great job on my bike,” says Miller, “but they wouldn’t make it on a working truck. Today, all tire manufacturers make specific tires for specific jobs. There are steer axle tires, drive axle tires and trailer tires.”

Truck tire repairs must not be done with rope type material as it cannot contain the inflation pressures for such tires. This repair was made in the shoulder of the tire, which is not fully reinforced by belts. Air leaked in around the repair and separated the cords, resulting in a potential for catastrophic failure.

There are tires made for on-highway applications and off-road tires. “We have tires for regional service that are better for high-scrub applications and some that are for service a little closer to long-haul,” he says.

All manufacturers rate their tires as to suitability for position and application. Only a few tires are designed to work in more than one position or application.

“The wrong tire or tread will not be as durable,” says Walenga. “They won’t die suddenly, but carefully matching the tire and tread pattern to the job and position will help extend a tire’s life significantly.” n


 

Other deadly tire issues

LACK OF A FORMAL INSPECTION PROGRAM. Regular inspection will enable you to fix problems before they cause irreversible, irregular wear or other damage. For example, an object lodged in the tread, if caught early, might not ruin the casing. Also, Goodyear’s Tim Miller says, “The wear pattern of a tire is a great insight into the state of alignment and steering systems, suspension and wheel ends.”

BRAKE HEAT. This comes from an improperly maintained, unbalanced brake system, says Michelin’s Doug Jones, often because stopping duties are not equally shared by all wheels. To prevent this, do brake jobs thoroughly, replacing all parts with new ones from a quality rebuild kit. Make sure all relay valves have identical crack pressures and response curves by using parts that meet manufacturer’s specs. To prevent overheating the wheels on extremely long grades, stop and allow brakes to cool, or stay at a low speed.

FLAT-SPOTTING. This is a major worry when one or more wheels lock up. Maintaining the braking system so all the brakes work in unison will help prevent flat-spotting, which is common on trucks still utilizing non-ABS brake equipment. Control the treadle valve and apply pressure when braking hard with such equipment, responding to lockup by backing off. On most modern vehicles, keeping up with ABS maintenance by responding immediately to any trouble codes from the system will prevent tire flat-spotting.