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Attorneys of Record for
Taras Kick
C. Tab Turner
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Firestone Announces the
Completion NASHVILLE, Tenn., Feb. 2 /PRNewswire/ -- Firestone today announced the completion of Dr. Sanjay Govindjee's analysis and technical report detailing why the recalled ATX and Decatur-produced Wilderness AT tires, primarily on Ford Explorers, experienced a higher rate of tread separation claims. Dr. Govindjee's findings and analysis independently confirm that there was no single causal factor. "In all cases, failure rates for the recalled tires are fractions of a percent and thus determining a single cause for the tire failures is an unrealistic expectation," said Dr. Govindjee, an associate professor of civil engineering at the University of California at Berkeley. "From a mechanical and materials engineering perspective, the phenomena of belt separation in these tires resulted from a crack that grew in the rubber between the two belts. This cracking is influenced by a number of factors, including climate, design of the tire, manufacturing differences at Firestone's Decatur plant and usage factors." Dr. Govindjee examined recalled tires to determine what could cause a fatigue crack or belt separation to grow between the two steel belt layers of the tires. His analysis, which included standard testing and new lab and field testing, found that climate played a critical role in reducing the material properties or capacity of the tires. For example, tires from warmer climates showed a substantial degradation in their material properties; further, tires that were run at high speeds, in highly loaded vehicles or at low inflation displayed pronounced heat build-up. While the effect of temperature on the capacity of the interbelt materials was confirmed, he also found the demands on the tires from extra loading were important in pushing a fatigue crack to grow. Further, his analysis showed that the interbelt material properties of the tires in question produced in Decatur, were substantially different from those at other plants and were more subject to fatigue. His analysis also found design differences in the Radial ATX could lead to a higher propensity to fatigue than the Wilderness AT. Dr. Govindjee focused on a mechanical and materials engineering analysis and, as a result, his report has some differences in scope and focus from Firestone's internal investigation, released December 19, 2000. His overall conclusions provide additional information consistent with the company's findings. "Firestone's technical staff is now thoroughly reviewing Dr. Govindjee's report as part of our quality assurance and continuous improvement program," said John Lampe, Bridgestone/Firestone Chairman, CEO and President. "We thank Dr. Govindjee for his hard work. I am confident that with our own internal review, combined with Dr. Govindjee's analysis, we have determined why some of our tires experienced a higher rate of tread separation claims and that our recall in August was more than adequate to protect the public." To determine how these factors affect tire life, Dr. Govindjee used information provided from Firestone and its research center and laboratory, independent laboratories and a survey of material properties from returned tires. His analytical work included the assessment of tire loading on the Ford Explorer, analysis of heating factors - which included an analysis of tire inflation pressure, loading and speed - and extensive finite element modeling. In addition, Dr. Govindjee used field data on Ford Explorers regarding actual dynamic loading or forces placed on the tires by the vehicle. This data was collected at Firestone's test track in Acuna, Mexico on a 1998 Ford XLT Explorer four-wheel drive. Measurements were performed at four different inflation pressures, four different cargo loads and at different speeds. Dr. Govindjee was retained by Firestone in September to provide an independent analysis of its recalled tires. While Firestone provided information and data requested by Dr. Govindjee, his work was conducted independently from the company's own internal review and analysis. Firestone has provided Dr. Govindjee's report and findings to the National Highway Traffic Safety Administration and other governmental groups. "I am grateful to Dr. Govindjee for his efforts in this analysis," said Lampe. "Finding the root cause of why a small percentage of our P235/75R15 ATX and Decatur-produced Wilderness AT tires suffered tread separations was a priority for this company, and we know it was extremely important to our customers. Dr. Govindjee's report is another step forward in assuring that the difficulties we encountered last year with this one particular tire size and type won't happen again. His report confirms and reinforces our earlier internal findings. It assures me that our company has taken the necessary and appropriate corrective steps to deal with this difficult situation. And it supports my firm belief that our company today is building the world class tires for which this company has been known over the past 100 years." For Dial Up connections (Report optimized for viewing) get the graphic optimized version (approx. 943k) click on this link http://www.firestonetire.com/REPORT_WEB_secure.PDF For High Speed connections (For news media optimized for printing) with full resolution graphics (approx. 18mb) click on this link http://www.firestonetire.com/REPORT_Secure.PDF To download Acrobat Reader click on this link http://www.adobe.com/products/acrobat/readermain.html (02/02/01)
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