Bridgestone/Firestone says it found answers in its dig for tire failure causes

By Ed Garsten
CNN Detroit Bureau Chief

NASHVILLE, Tennessee (CNN) -- After a four-month investigation that involved cutting apart 850 tires and examining more than 2,500 recalled tires, Bridgestone/Firestone thinks it has a good idea why the tread was separating on some of its tires. To the surprise of many observers, the company is accepting some of the blame.

The federal government has tied the faulty tires to at least 148 deaths. The tire company recalled 6.5 million 15-inch Wilderness AT, ATX and ATX II tires in August. That effort, according to Bridgestone/Firestone, is more than 85 percent complete.

The "root cause" investigation by the tire maker found what it believes are four major contributing factors:

  •  A problem existed with the tread design in ATX tires, which has since been corrected. The problem involved the shoulder pocket, a term for the spot where the tread and wall of the tire meet. The design of the pocket caused tires to be prone to cracking, which may have led to tread failure.

  •  ATX P235/75R15 and Wilderness AT tires produced at the Decatur, Illinois, plant had problems with rubber adhering to steel belts, caused by a process unique to that plant. This problem could also have led to tread separation.

  •  Bridgestone/Firestone puts some of the blame on Ford. It claims that "vehicle load level and low standard tire pressure...led to a decreased margin of safety for tire performance."

Most of the recalled tires were installed as original equipment on Ford Explorer SUVs. The tire maker claims Ford built heavier and heavier vehicles, putting strain on the tires.

The company also takes issue with Ford's recommended tire pressure of 26 pounds per-square-inch. Bridgestone/Firestone preferred 30 to 35 psi. Ford said Tuesday, however, that it stands by its vehicles and believes that it did not in any way contribute to tire tread separations.

  •  Bridgestone/Firestone believes the fourth factor was inadequate maintenance. The tire maker claims that drivers often do not keep tires properly inflated. An under-inflated tire becomes prone to heating up, which may also lead to tread separation.

So what is Bridgestone-Firestone doing to correct these root problems?

In addition to the defective shoulder pocket design problem, the inflation issue has been addressed. Shortly after the recall began, Ford agreed to increase its recommended inflation rate to 30 psi, although the automaker still contends 26 psi is sufficient.

The problem in Decatur is being corrected, according to Bridgestone/Firestone, which says it is changing the manufacturing process at that plant.

On Wednesday, the tire maker's parent company, Tokyo-based Bridgestone Inc, announced it would institute a "global standard" for tire development.

Both Ford and Bridgestone/Firestone claim the tread separations caught them by surprise, even though lawsuits had been filed as early as 1993. But in its root-cause report, the tire maker said it would improve the way it collects, monitors and analyzes defect claims in order to respond more quickly to problems with its products.

What may be a larger problem for Bridgestone/Firestone is whether the public will regain its trust in the 100-year-old Firestone brand. Sales of Firestone tires plummeted 40 percent after the recall began .

Ford, which has a century-old relationship with Firestone, is now offering consumers a choice of tires on the 2002 Explorer, which goes on sale early next year. In the past, Firestone tires were standard equipment.

Consumers who still trust Firestone may find it more difficult to find them. Several dealers told CNN that if their sales didn't bounce back, they might drop the brand. One longtime dealer has already removed all Firestone signs and logos from his store even though he still carries the tires.

University of Detroit-Mercy marketing professor Michael Bernacchi believes the venerable brand may never recover and could be gone within a year.

Firestone, Ford threatened with Venezuelan legal actions
September 30, 2000
Bridgestone/Firestone executive says complaints didn't reach him
September 16, 2000
Highway safety head undergoes baptism by Firestone
September 11, 2000
Firestone spreads blame
September 11, 2000
Senate committee approves tougher auto-tire safety disclosures
September 20, 2000

Bridgestone/Firestone
National Highway Traffic Safety Administration
U.S. Senate Committee on Commerce, Science, and Transportation
Consumers Union

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