By TIMOTHY AEPPEL, STEPHEN POWER AND NORIHIKO SHIROUZU
Staff Reporters of THE WALL STREET JOURNAL
Continental General Tire Inc. is expected to announce a recall of about
200,000 tires supplied to Ford Motor Co. because of tread-separation
problems, adding more woes to the auto maker already embroiled in the
massive Firestone recall.
Separately, Ford said company engineers have
determined that the left rear tire on all vehicles,
including the popular Explorer, is the most
vulnerable to failure or tread separation, but
haven't made "a clear-cut finding" as to why.
Officials of Continental General, the U.S. unit of Germany's Continental
AG, and Ford are meeting in Washington Tuesday to brief the National
Highway Traffic Safety Administration about failures of Continental tires
that were supplied for Lincoln Navigators.
Why the Left Rear Tire?
Possible explanations behind why Ford Explorers' left rear tire treads
blew off more frequently than other tires' treads.
Fuel tank is by left rear tire.
Drive shaft movements tend to load the left, rather than right rear
'Reflective energy': Grass or gravel on the right hand side of the
road keeps that side cooler than the concrete or asphalt on the
left. High temperatures put more stress on a tire.
Continental supplied a total of nearly 700,000 tires to Ford for
Navigators over the last three years. However, people close to the
situation say the replacement action would focus on a group of fewer
than 200,000 tires, just a portion of the 16-inch tires supplied in 1998
and 1999. Navigators switched to using a 17-inch tire in 2000.
The Continental replacement action is expected to take place in the U.S.
as well as overseas. Last week, Ford acknowledged it had experienced
possible tread-separation problems with Continental tires on Navigators
in Saudi Arabia, the same country where early problems with Firestone
tires surfaced. People close to the situation say Ford has encountered
similar problems in the U.S.
In a joint statement, both companies noted that "the information the
companies will share with NHTSA includes no reports of serious
accidents, fatalities or serious injuries." No rollover accidents, the main
source of injuries and deaths in accidents linked to Ford Explorers with
Firestone tires, are known.
NHTSA officials said there are no investigations at this time regarding
Continental tires failing on Navigators. Ford requested the meeting to
discuss complaints about tread separations on those tires in Saudi
Arabia. The two companies plan to brief the NHTSA on Continental's
warranty and claims experience in the field for 1998 and 1999 Lincoln
Navigators with 16-inch ContiTrac AS tires.
Meanwhile, congressional investigators, poring over reams of
documents turned over by Ford and Firestone on Friday, participated in
conference calls with company officials, questioning them about test
data on the tires that go back years. "You're looking for that one
document that says, 'we have 800 accidents involving tread separation,'
or 'eight accidents involving tread separation,' " a congressional staffer
said. "The problem is, test people don't write that kind of stuff. They tell
you it failed or it went so far. And unless you know what the test was
done for, you don't know what it means."
Ford dismisses the notion that the greater failure tendency of the rear
tires, and especially the left rear tires, of the Explorer helps explain the
large number of Firestone tire failures that led to last month's recall by
Bridgestone/Firestone Inc., a unit of Japan's Bridgestone Corp. But
others, including Bridgestone Chief Executive Yoichiro Kaizaki, note that
the bulk of the Firestone tire failures have occurred on Ford Explorers
and suggest the vehicle could be part of the problem.
The fact that most of the Firestone tire-tread separations involve the
left rear tire could help determine if there is something about the vehicle
itself that contributes to the tire failures, tire experts say.
Both Ford and Bridgestone/Firestone are still trying to pinpoint what is
causing so many accidents involving Firestone tires on Ford's Explorer.
The NHTSA has reported more than 1,400 complaints, 88 deaths and
250 injuries stemming from accidents during the past decade in which
Firestone tire treads separated.
Ford says there are several possible reasons the left rear tire may fail
more often. Mr. Vaughn notes that is where "the fuel tank is." As a
result, there is more static weight there, which would mean a constant
and heavy pressure in that area. He also said that the way the drive
shaft turns tends to load more pressure on the left than on the right
Driving habits also put more stress on the left rear tire. People tend
drive in the right lane, thus the right tire is bordered by grass or gravel.
The left tire is bordered by more asphalt or concrete, which has a higher
temperature. The theory, according to Mr. Vaughn, is that the concrete
and asphalt produce "reflective energy." Increased heat on a tire can
lead to tread and belt separation.
Dick Baumgardner, a tire expert who often testifies against tire makers
in lawsuits, has studied about 50 accidents involving the recalled
Firestone tires since 1995, and says he has noticed a pattern. About
80% of the time, the accidents occurred after the failure of a rear tire.
And in about half of the 50 cases, it was the left rear tire that failed.
He believes the rear-tire failures on the Explorers cause a "steering
reaction that can't be controlled by the driver." That, coupled with the
high center of gravity of the SUVs, leads to the high incidence of
Tire makers insist there is no reason a tread separation should result
an accident. They point to the prevalence of tread separations -- as
evidenced by the mounds of tire treads on the edges of highways.
"Tires fail from separations, but that's no reason for a vehicle to go
of control," says Harold Herzlich, a tire consultant who often works for
tire makers. Mr. Herzlich says that even if a rear tire on a vehicle fails,
basic rules of physics still apply: Objects in motion want to keep moving
forward in a straight line.
A vehicle that loses a tire tread will be pulled "slightly" toward the
the failure, he says, but most drivers should be able to compensate and
slowly bring the car to a stop. Mr. Herzlich acknowledges, however, that
some drivers may be startled by the loud noise of a tread coming loose,
stepping on the brakes or turning sharply in their confusion.
Separately, Ford said tires on its 2002 Explorer will require a higher
tire-inflation rate because the vehicle will use 16-inch tires and has a
third-row seat that makes the vehicle heavier. Ford spokesman Jason
Vines said Ford hasn't yet determined what its recommended level of
tire inflation for the 2002 Explorer will be.
Tire pressure has emerged as a crucial issue in the Firestone debacle.
When tire pressure is low, sidewalls flex more than they are meant to as
the vehicle travels down the highway. All that extra flexing can quickly
build up high levels of heat inside the tire, which can damage the bonds
that hold the tire together.
Firestone has recommended that the tires be inflated to 30 pounds per
square inch, while Ford initially recommended 26 pounds per square
inch, although it now recommends a range of 26 to 30 pounds per
square inch. Ford said the higher tire inflation rate for the 2002 models
is not the result of the Firestone recall.
Write to Timothy Aeppel at firstname.lastname@example.org, Stephen Power at
email@example.com and Norihiko Shirouzu at