Firestone, Ford Bid to Cut Probe Short

In singling out design and manufacturing issues as root causes of disastrous Firestone tire failures on Ford Explorers, Bridgestone/Firestone and Ford Motor Co. are trying to convince federal regulators and their congressional overseers that their investigation and recall need go no further.

But initial reaction Tuesday from the National Highway Traffic Safety Administration and from Capitol Hill suggests that Ford and Firestone still have some persuading to do.

“It’s almost like they are trying to put a fence around the whole thing,” said a congressional staffer, who noted that the role played by the Ford Explorer in the fatal crashes has scarcely been addressed by the two companies.

“I think we only have one piece of the puzzle,” said the staffer, who was briefed by Firestone on its findings. “It’s like trying to find out what’s wrong with a complete human being and you only have a report from the foot doctor. We have to wait to see what the other doctors say.”

Whether to accept the companies’ analyses or broaden the investigation may well be one of the first safety-related decisions the new Bush administration has to make.

On Tuesday, NHTSA released more than 90 pages of documents from Ford and Firestone showing that the companies generally agree that small interior cracks--invisible from the outside--began the deadly chain of events.

The cracks spread between the tires’ inner belts because of heat buildup, particularly in a sensitive area where the tread meets the sidewall. Overheating gradually weakens the tire’s rubber and its cohesiveness, allowing the tread to come off.

The overheating was intensified by the design of Firestone’s ATX tires and by other factors such as under-inflated tires, the company investigators concluded.

A unique manufacturing process at Firestone’s aging Decatur, Ill., plant--where many of the tires were built--was also cited as a contributing factor, since it produced a rubber material more vulnerable to heat. The company said Tuesday it is making changes in that process.

Indeed, Firestone declared that the problems have been found and corrected.

“Our recall in August was more than adequate to protect the public,” said John Lampe, Bridgestone/Firestone’s new president. The problems “are unique to the recalled tires,” he stressed, adding that “other Firestone tires perform at world-class levels.”

Firestone has replaced more than 5.6 million of the estimated 6.5 million tires it recalled Aug. 9. The recall covered ATX and ATX II models and 15-inch Wilderness tires built at Decatur. NHTSA has received reports of at least 148 deaths linked to the tires under investigation.

Ford’s analysis, which ran more than 70 pages, also drew a distinction between the recalled tires and other Firestone models under scrutiny by NHTSA, such as the 16-inch Wilderness tire.

However, critics said the companies have not done nearly enough testing to rule out problems with other tires or with the Ford Explorer.

“Tires outside the recall have been excluded from this analysis,” said Sean Kane, president of Strategic Safety, a consulting firm that helped bring the problems to public attention. “That concerns me.”

Kane noted that the ATX and ATX II are older Firestone models no longer produced, and possible problems with the company’s new line of Wilderness tires may simply not have had enough time to emerge.

“The wild card . . . is what is going to happen with these tires as they age,” he added.

Firestone has told federal investigators that its newer Wilderness tire is more solid than the ATX models, and thus unlikely to encounter a problem.

However, NHTSA spokesman Rae Tyson said the agency will not accept the companies’ conclusions at face value. “We are doing our own investigation,” he said. The agency has also found high rates of failure in other Firestone models, including the Firehawk ATX. The company declined to launch a recall, but offered to replace the tires for customers with concerns.

Additional details about the recalled tires surfaced in the documents released Tuesday.

A Firestone analysis partially explained why rear tires were more likely to fail than front tires on Ford Explorers, and why the left rear tire failed more often than the right rear tire. The analysis found that rear tires ran some 20 degrees hotter than front tires, and when tires are under-inflated, the left rear tires ran about 10 degrees hotter than the right rear tire. But it didn’t explain the differences.

Rear tire failures are more dangerous than front tire failures, since drivers cannot easily control the skidding vehicle.

An additional report is expected soon from an independent expert retained by Firestone. And NHTSA has pledged to announce the findings of its own investigation by springtime.