Bridgestone Blames Tire Woes on Design, Ford

Bridgestone/Firestone Inc. says failures in its recalled tires are due to a combination of tire design, manufacturing problems at its Decatur, Ill., plant and customer abuse.

A new study prepared by the company and released today details the results of a four-month internal investigation.

Engineers who conducted the investigation found that flaws in the tires blamed in at least 148 U.S. deaths may in part be the result of the process used to mix the rubber used in the tire-manufacturing process.

The Decatur plant uses a process known as pelletizing, where rubber pellets are blended with a lubricant to create the rubber that coats the steel belts of the tire.

This process is unique to Decatur. Other plants use a slab system that does not involve pellets.

Wedge of Woe

The tire maker also found a problem with the wedge area of the tire, located near the shoulder where the tread meets the tire wall on the recalled ATX model. These scalloped areas help give the tire traction.

But the investigation did not entirely blame the company — it found that Ford let the weight of its Explorer vehicle increase throughout the mid-1990s. That could have pushed the SUV’s weight closer to the tires’ load-bearing capacity.

Customers were also to blame, the company said. The report claims some drivers did not keep their tires properly inflated, and did not fix flats properly.

Firestone vs. Ford

Firestone continues to insist that the lower inflation pressure recommended by Ford Motor Co. played a role in the tire failures. Ford recommended that Firestone tires on the Explorer sport utility vehicle be inflated to 26 pounds per square inch, while Firestone recommended 30 psi.

A Ford spokesman, Ken Zino, said the automaker is continuing its investigation and has yet to come up with a root cause for the failures.

“In our discussions with both NHTSA [the National Highway Traffic Safety Administration] and Firestone we discussed tire design and manufacturing problems, and we still don’t see the Explorer as the issue,” Zino said.