A couple of days ago, a post was made concerning Firestone/tire pressure/Ford Explorer. It was stated that Ford had reduced recommended tire pressure to an unsafe level for the tires that were on the vehicle, or something to this nature. It was further stated this was an attempt to help reduce the tendency of the vehicle to roll over. The person who wrote this must have been sitting in a different meeting than me. In my meeting, there was a pre-launch issue of excessive road noise due to a change in the carpet and underlayment which produced a lot of noise. The solution? Drop tire pressue. Assignments were given to several people to get Firestones' buy-in to the lowered pressure. They got the OK from Firestone and that's how the road noise problem got closed off the launch matrix. Don't recall any conversation of roll over. Remember, the manufactuers tell the tire companys what they need and then the tire companys design to accomodate the specs set by the auto manufacturers. I wouldn't bother with this except my pension check comes from there and I'd like to keep the record straight.
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Re: To clarify a point on tire pressure
My statements were based on a recent book about the Explorer/Firestone fiasco. The primary sources were deposition and trial transcipts and various supporting documents presented during discovery and trial. Ford denied the rollover issue as being a factor in their tire pressure recommendation, but documents and testimony proved otherwise. Ford engaged in a coverup to save their butt, but it didn't work. After losing one trial they settled most of the other cases. They had no choice as the cat was out of the bag, and Ford clearly had culpability in the issue. So did Firestone because the tires were not up to minimum industry or federal quality and performance standards. Tire failure led to loss of vehicle control and the Explorer's relative lack of rollover resistance led to an very high rollover rate after tread separations.
The documents and testimony indicate that Ford understood the Explorer had a relatively high propensity to roll over - much higher than the Ranger pickup truck built on the same basic chasses - and the low recommended tire pressure - 24 psi - was recommended because the lower lateral grip that lower tire pressure afforded reduced the rollover tendency.
You definitely don't want sticky rubber on the first generation Explorer (before the current IRS model) as it may increase the rollover tendency. Low lateral grip will increase the tendency to spin if the driver looses control, which is a "safer" way to dissipate kinetic energy than rolling.
I don't recall the book's name, but I found it at my local library in the new books section, and I believe it was a non-fiction best seller for awhile. As far as I could tell the author provided a reasonably objective account though he clearly was not a fan of Ford's behavior.
It certainly wasn't the first time big business had tried to coverup their erros and poor judgment, and it undoubtedly won't be the last.
Duke -
Re: To clarify a point on tire pressure
With all due respect to your evidence, I stand on my statement. The decision to reduce tire pressure was was made to settle an NVH concern after the last prototype build and prior to Job 1 production. I still have a copy of the design problem/concern matrix where it states same. I remember sitting in the meeting thinking that Firestone will never agree to a tire pressure this low.
At the time, it was quicker, easier and cheaper for Ford to convince Firestone to drop air pressure than for Ford to redesign the interior components that caused the problem and delay a model launch. This is not to say the chassis design guys were not delighted to hear the tire pressure news. They may have realized it would help reduce the tendency for the vehicle to tip over.
Prior to the tire failures, according to one printed source, whose identity escapes me, the Explorers were less likely to be involved in a roll-over than some of the other high center of gravity vehicles in it's class.Comment
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Read the book. *NM*
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