Complete Firestone Letter To NHTSA : It's Fords Fault!
May 31, 2001
Mr. L. Robert Shelton Acting Administrator National Highway Traffic Safety Administration 400 7th Street, S.W. Washington, D.C. 20590 Via Fax
Dear Mr. Shelton:
Today, I am requesting that the National Highway Traffic Safety Administration open an investigation into the safety of a certain models of Ford Explorers. Testing done by Dr. Dennis Guenther, a Professor of Mechanical Engineering at The Ohio State University, the results of which are now in the possession of Bridgestone/Firestone, Inc., shows that certain of the Explorer models will experience an "oversteer" condition in most circumstances following a tread separation on a left rear tire, an event which is clearly foreseeable. In his analysis, Dr. Guenther says: "An oversteer vehicle is not safe at highway speeds in the hands of an average driver. This must be regarded as a highway safety defect within the meaning of the NHTSA's charter." Based on his initial findings as reported to Firestone, Dr. Guenther has concluded that the Explorers as tested are defectively designed in that they have an inadequate margin of control (due to insufficient understeer) to permit control by average drivers in the foreseeable events of tread separation during normal highway driving in most load and turning circumstances. This can make the Explorer's handling imprecise and unpredictable in foreseeable circumstances, such as tread separation, where precise and predictable handling is essential to safe vehicle control. As I have said many times in the past, it is critically important to look at the tire and the vehicle as an integrated system. What affects one, affects the other. We ask NHTSA to investigate to determine the cause of the serious safety issue with a substantial segment of Ford Explorers and to take the necessary steps to remedy the potential defect so as to protect motor vehicle safety. A complete copy of our analysis has been given to your office. As always, we stand ready to offer you any assistance you think is necessary. Thank you for your consideration.
John T. Lampe
cc: Dr. Dennis A. Guenther Professor The Ohio State University