FIRESTONE SAYS THE FORD EXPLORER HAS A
DESIGN DEFECT AND BLAMES IT FOR THE ROLLOVER AND STABILITY PROBLEM
May 31, 2001
Mr. L. Robert Shelton
National Highway Traffic Safety Administration
400 7th Street, S.W.
Washington, D.C. 20590
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
John T. Lampe