What Are the Causes of Broken Belts in Tires?

Auto Safety explains the Firestone tire recall of 1978. The largest tire recall to date occurred when Firestone recalled 14.5 million steel belted radials. The Firestone tires were sold under other names, as well as Firestone, such as Wards, Shell, National, Seiberling, LeMans and Kmart.

Firestone switched to new tire technology to keep up with competitors, Goodyear and Michelin. The new radial tire-building machinery and process required rubber components attached to a brass coated steel wire in the tire's inner belts. The radial belt and the tread separated when the outside tread spilt from the rest of the tire or the inner steel belts came loose from the rest of the tire. The Firestone 500 steel belted radials resulted in the death of an Alabama State Policeman in 1974.

Attorneys Smith and Fuller provided tire terms to clarify aspects of tire safety. Belts are steel cords within rubber layers of tires under the tread that help the tire retain its shape and help keep the tire puncture proof. The tread is the outer, wear-resistant layer of the tire located above the steel belts. Tread bonds to the tire under heat and pressure in a process called vulcanization. Tread separation has occurred as a result of improperly cured tires when workers shortened the curing times to produce more tires in the day or because a worker dropped a chicken bone from his lunch into the manufacturing process. Belt wedges are rubber pieces inside the tire fused at the edges of the belts to reduce heat, stress and wear on the tire.

Tread separation, claims attorneys Smith and Fuller, would probably not occur if the manufacturers were equally diligent in manufacturing all their tires. When the tread of the tire separates from the inner air compartment, the tire remains inflated, and the vehicle lurches to the side. Suddenly, the driver, in motion on the highway, driving on a tire with no tread, loses control of the vehicle resulting in injury or fatality. The Medina Law Firm lists sample cases of tread separation. Juries usually award damages to the victims in these personal injury cases. Over-inflation of tires to get better gas mileage can also cause tread separation.

Only specially trained mechanics should mount tires. According to Goodyear, the tire rim assembly could explode if the tire is not mounted properly. Underinflation or overloading is dangerous. Tire air pressure should be checked frequently.

Oversteer occurs when the rear tires are at a greater angle than the front tires. Tread separation causes the vehicle to oversteer and become difficult to control. During oversteer, the rear of the vehicle "fishtails" and spins one way, then spins back the other way.

According to Goodyear, nylon safety overlay strips are an important safety component designed to prevent tread separations and decrease stress at the steel belt edges. Some tires have nylon overlays that cover the entire belt structure for multiple layers of protection.