| Firestone-Ford Field Data Summary
Firestone and Ford Motor Company released
detailed information August 13 related to Firestone's safety recall
of all P235/75R15 Radial ATX and ATX II tires, as well as Wilderness
AT tires of the same size produced at Firestone's Decatur, Ill.,
plant.
This analysis of Firestone tire field data
was conducted by Ford and Firestone engineers and computer technicians.
The following ten charts summarize the analysis, identifying
the type of tires accounting for the tread separations reported
to date and it identifies safe tires with superior field performance
to be used as replacements in the recall.
This chart (above) illustrates the rate of claims
in the federal government's safety agency's records of Firestone
tire complaints of all kinds over the past ten years. It depicts
the number of Vehicle Owner Questionaires (VOQs) from the National
Highway Traffic Safety Administration (NHTSA) database for all
Firestone tire complaints on Ford Explorer, F-150 and Ranger vehicles.
Considering the millions of Firestone tires over 10 years of production
of these three vehicles, the number of complaints recorded was
extremely low until very recently. No discernable trend was evident
from this data until the publicity effect began this year.
This chart (above) shows counts of Firestone
customer claims (primarily warranty claims for property loss but
also including injury claims and lawsuits). P235/75R15 tires accounted
for 2030 claims, by far the largest source of claims against Firestone
for the past 10 years.
An analysis of the 2030 claims involving Firestone
P235/75R15 tires shows that the ATX (including ATX II) tires comprise
the overwhelming portion of claims. Wilderness AT tires account
for less than 1/11 of the number of ATX claims. Further, claims
involving tread separation account for more than 70 percent of
the total ATX claims and about 35 % of Wilderness tire claims.
Four states – Texas, Arizona, California
and Florida – account for more than 80 percent of the tread
separation claims for Firestone 15" ATX tires. Tread separation
claims in northern states are extremely rare.
The rate of claims for tire tread separations
reported for Firestone ATX tires for the 1996 tire production
year (248 incidents per million tires) was 11 times higher than
for Wilderness AT tires (22 incidents per million tires), produced
in the same year and therefore with a similar time in service.
The overall rate of claims of tread separations
involving Firestone ATX tires from all plants show an increasing
rate from 1991 to 1996 production years. ATX tires were discontinued
as OEM tires in 1996, replaced by Wilderness tires, which have
had a markedly lower claim rate. Firestone continued to manufacture
a smaller number of ATX tires to be used as replacements; these
tires also show a markedly reduced claim rate.
This chart (above) takes a magnified look
at the most recent years of production of Wilderness P235/75R15
tires. For the 1996 production year, claims involving 15"
Wilderness tires produced at Decatur occurred at a rate of 66
per million tires produced. The claim rate for Decatur-produced
15" Wilderness tires has fallen in subsequent years, although
the 1998 and 1999 tires have been in service a limited time. Tire
built at plants other than Decatur have been involved in much
fewer tread separation claims – 1/10 as many for the '96
production year and 1/34 as many for the '97 production year.
In fact, 15" Wilderness tires produced at Firestone plants
other than Decatur are performing at world-class levels of safety
and quality – only one claim per million tires in the 1997
production year.
This chart (above) shows the cumulative claim
rate for P235/75R15 ATX tires produced at Decatur and all other
Firestone plants from 1991 to 1996. The claims rate for ATX tires
is steepest between two years and five years after production
and then quickly falls off to a flat rate (i.e., very few new
claims). Although the claim rate is much lower for the non-Decatur
plant, a similar pattern follows – most claims occur two
to five years after production.
Using the same scale as the previous chart, this
chart shows the much lower cumulative claims rate for P235/75R15
Wilderness AT tires produced at Decatur and all other Firestone
plants from 1996 to 1999. Claims appear to be almost non-existent
for tread separations on non-Decatur-produced 15" Wilderness
AT tires, but we need to magnify the scale (next chart) for further
review.
This chart (above) greatly magnifies the
previous chart, showing cumulative claims rate for P235/75R15
Wilderness AT tires produced at Decatur and all other Firestone
plants from 1996 to 1999. Claims are almost non-existent for
tread separations on non-Decatur-produced 15" Wilderness
AT tires. These tires are performing at world-class levels.
New non-Decatur-produced Wilderness AT tires are being used as
replacements in the recall.
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