With the public acknowledgement that its Decatur plant was partly responsible for the tread separation on its Wilderness AT and ATX I and II tires used on the Ford Explorer, Firestone worked last week to regain the trust of the American public --while trying to keep Ford Motor Co. on the hook for the design of the vehicle and the difference in recommended tire pressures.
The results were mixed. The Firestone findings, announced the week prior, revealed little more than what had been leaked out during the last two months: a combination of the tread design, manufacturing defects and external factors resulted in tread separation. The external factors were, according to Firestone, vehicles that were improperly loaded with cargo and the tire pressure recommended by Ford.
Firestone submitted the results of inquiry to the National Highway Traffic Safety Administration (NHTSA) and Ford, saying it was confident that after each had time to review the report that they would both concur with the findings. NHTSA had no formal comment regarding the findings.
In addition to submitting the findings for review, the company restated its beliefs that it acted appropriately and effectively in recalling the tires involved.
"Our team's findings confirm what the initial statistical claims information demonstrated from the outset: That a small number of tires generated higher rates of separation claims when used on Ford Explorers and that our recall initiated in August was more than adequate to protect the public," said John Lampe, Bridgestone/Firestone chairman and CEO.
In addition to its own internal study, the company contracted an outside investigator, Dr. Sanjay Govindjee of the University of California-Berkeley, to conduct an independent investigation. Govindjee, an associate professor in civil engineering, said in preliminary report indicated that internal cracks develop inside the tire and cause the tire to fatigue and eventually lead to tread separation. Govindjee's final results are expected by the end of this January.
The company outlined the four primary factors that combined to cause problems with the tires:
- The shoulder pocket design of the tires could lead to cracking at the shoulder pocket bottom. This could become the starting point of a failure;
- Low inflation pressure in the recalled tires increased the running temperature of the tires;
- Vehicle load levels and low standard tire pressure, initially specified for the primary vehicle for which the tires were designed, led to adecreased margin of safety for tire performance;
- Tires produced at the Decatur, Ill., plant exhibited different belt adhesion characteristics, including initial adhesion, than those same size and line tires produced at other plants.
According to Firestone officials, it has taken steps to correct some of the problems. It has instituted a change in the manufacturing processes at the Decatur plant. Additionally, it said Ford has changed its recommended tire from 26 pounds per square inch to 30 psi.
Ford released a statement suggesting it was reaching similar conclusions about the tires, but not accepting any role regarding the impact the recommended tire pressure or design of the Explorer may have had in the failure of the tires.
"While Ford's investigation continues into the cause of Firestone tire tread separations, our preliminary root cause hypothesis is: The design of the tire generates high stresses and heat in the wedge and belt area," the company said in a released statement. "Manufacturing processes at Firestone's Decatur Plant reduce the cohesion level of the rubber in that same area of the tire. This reduced strength permits cracks to propagate between the steel belts.
"We believe it is a combination of manufacturing factors and the reaction of the tire design to field operating conditions including hot weather and very low tire pressure, that have caused the increased failure rate of these tires."
Firestone for its part continued its attempts to make Ford culpable while putting on a brave face regarding its future. Some analysts have speculated the company may never recover from this kind of event. Lampe wasn't buying into the hype.
"Our engineers and analysts found through their review of the data a higher claims rate for those tires we recalled," he said, "but this same data reinforced our belief that other Firestone tires perform at world-class levels. We committed to our customers and the motoring public to find out why some Firestone tires were more likely to experience tread separations on Ford Explorers. That has been our principal focus since we announced our recall effort in August."
Settlements keep Ford on the hook
While continuing to maintain it is not responsible for the tire fiasco, Ford has quietly settled eight lawsuits related to the tire problems. All eight cases were settled in Florida. More than 200 lawsuits have been filed against Ford related to tire problems. The lawyer involved in six of the cases said that he was approached by Ford to settle the cases, which he thought was unusual.
Ford spokeswoman Susan Krusel told Reuters that it was not odd for the automaker to settle the cases and that most cases of this nature are settled out of court.
All of the settled cases were personal-injury suits filed in state court in Florida. Settling cases is not out of the ordinary, but three of the cases were settled before they were scheduled to go to trial while three more had not even been filed yet. In each of the settlements, Ford took responsibility for its role in each of the accidents without admitting there was a problem with the Explorer.