WHAT IS WRONG WITH SOME FIRESTONE TIRES ?  WHY SO MANY TIRE TREAD SEPARATIONS ? 

 

The first problem is the design of the tire itself. Many of the tires are developing what is called fatigue failure, which basically describes the sudden and catastrophic separation of a device (tire) into two or more pieces caused by the application of loads or deformation over time. Fatigue usually occurs after the initiation and spreading of a crack. Both Ford and Firestone agree that the tires in question are experiencing steel belt separations or cracks beginning at the belt edge.

 

 Most tire tread separations begin at the edge of the # 2 belt or upper belt in which has the highest point of stress. >From the start of the crack, the growth aims toward the center in a wedge formation. The final stage of the failure is a total or partial separation of the upper belt from the lower belt and tire hull or carcass.  Studies have shown that the cracking and separation patterns of the Firestone Wilderness AT tire at the Decatur plant have the same shape and consistency as those observed from Firestone's Wilson plant. The Wilderness AT tires at the Wilson plant were not included in the recall, even though they are the exact same tire.

 

Another major problem with the Wilderness AT tire is the issue of durability. The tires are to sensitive and not designed, engineered, or manufactured for the tough expectations that the typical SUV consumer expects from the vehicle or the standard equipment (tires). The tires need to be tough enough to overcome the real world situations that a SUV will reasonable encounter, not that of a test track , under controlled conditions. Unfortunately, most SUV's have  tires that only meet the minimum requirements and therefore cannot hold up to the dangers that exist to the motoring public. Many tires have been intentionally designed that were undersized or under-weighted to achieve or fix another problem with the vehicle itself.

 

Smaller tires help lower the center of gravity, therefore lowering the rollover propensity. Lower tire pressures also help in this problem area too. Lower tire pressures however, with less air, create extreme temperatures and help promote or accelerate the rate of tire tread failures and separations. Some tires including the Wilderness AT were designed to be lighter in weight than comparable other tires to also fix the SUV's problem with excessive vehicle weight. Lighter tires, means lighter vehicle, creating better gas mileage. The lighter tires, with less rubber, with lower tire pressure on SUV's that are too heavy for the tire, with minimum numbers of belts are nothing more that pressure cookers waiting to explode.

 

It is believed that the tread design of the ATX and Wilderness AT tires may also contribute to the build up of excessive heat at the pockets or lugs on the outer edge of the tire tread. The excessive heat increases the crack formation. The pocket or lugs design allows for the development of exterior cracks as well which tend to enlarge during rolling deformation and can act as an inflator or pump of water, debris inward into the inner steelbelts causing rusting of the steelbelts and weakness of the central structure that the tire is formed. Once the inner core is weakened, this cancerous type of process of destruction is unstoppable and potentially dangerous.Other sources for tire tread separation and failures include the lack of a nylon overlay, the 1 X 5  wire cord design used in the steel belt construction, the skim compound used has poor rubber to wire adhesion characteristics, the lower recommended tire pressures, lack of overall quality control at the Firestone plants, including but not limited to the Firestone plant at Decatur.

HISTORY OF THE FIRESTONE TIRE RECALL & FORD EXPLORER ROLLOVER PROBLEM

 

In August 2000, Firestone determined that a safety-related defect existed in all Firestone P235/75R15 ATX tires and in Wilderness AT tires of that size manufactured at its Decatur, Illinois plant, and recalled those tires. NHTSA's Office of Defects Investigation (ODI) has conducted an extensive investigation to determine whether other Wilderness tires, beyond those recalled by Firestone, contain a safety-related defect, and whether they should be recalled.NHTSA's initial decision applies only to P235/75R15 and P255/70R16 Wilderness AT tires of the design supplied to Ford as original equipment. It does not apply to other tire sizes of Wilderness AT tires, such as those supplied by Firestone to General Motors and Toyota as original equipment, since those tires have different design features and have experienced relatively few tread separations.

 

Most of the tires subject to today's NHTSA decision were manufactured at Firestone's Wilson, North Carolina and Joliette, Quebec, Canada plants. Fewer than 100,000 of these tires, in the P235/75R15 size, were produced at the company's Oklahoma City plant. Tread separation failures on the Wilderness AT tires covered by NHTSA's initial decision have led to numerous claims and crashes, approximately 50 injuries, and 25 reported fatalities. Although these figures are lower than those for the recalled ATX tires, this is because the Wilderness AT tires have not been in service as long. Plant-by-plant failure trends for these tires are very similar to those of the recalled ATX tires over similar periods of service. Their failure rate is also significantly higher than that of competitors' tires used on SUVs, especially the Goodyear tires used as original equipment on the Ford Explorer.

 

DRIVERS LOOSE CONTROL OF VEHICLE WHEN TIRE TREAD SEPARATES

 

The tread separations at issue in this investigation reduce the ability of a driver to control the vehicle, particularly where the failure occurs on a rear tire and at high speeds, and can lead to a crash. The likelihood of such a crash, and of injuries or fatalities, is far greater when the tread separation occurs on an SUV than when it occurs on a pickup truck. Claims and complaint data indicate that a tread separation on an Explorer is no more likely to lead to a crash than on other SUVs. See: Rollover Tire Defects

 

Like other radial tires, the Wilderness AT tires have two steel belts. Tread separations typically begin as belt-edge separation at the edge of the top belt, the area of highest strain in a steel-belted radial tire. Once belt-edge separations begin, they can grow and develop into cracks between the belts. If they grow large enough, they can result in catastrophic tread detachment, particularly at high speeds.

In these Wilderness AT tires, the design of the "shoulder pocket" can cause higher stresses at the tire's belt edge. The tires often exhibit a series of weak spots around their circumference, leading to the initiation and growth of cracks earlier than in competitors' tires and in other Firestone tires used on light trucks.

 

A critical design feature used by tire manufacturers to suppress the initiation and growth of belt-edge cracks is the "belt wedge," a strip of rubber located between the two belts near their edges on each side of the tire. The belt wedge thickness in the ATX and these Wilderness AT tires produced prior to May 1998 is typically less than those of competitors' tires. These tires did not adequately resist the initiation and growth of cracks between the steel belts.

 

During March and April 1998, Firestone phased in a thicker wedge gauge, which then became comparable to competitors' tires, and revised its material composition. These modifications would tend to inhibit the initiation and spread of the belt-edge cracks that lead to tread separations. Moreover, there have been very few tread separation failures of the tires with the improved wedge, and NHTSA's inspection of used Firestone tires indicates that these tires have less severe cracks and separations between the belts than tires built before these changes.

 

For these reasons, NHTSA did not include the tires with the improved belt wedge in its initial defect determination. However, because tread separation failures rarely occur in these tires until at least three years of use, NHTSA cannot determine whether their actual field performance is significantly better than the older tires. NHTSA will continue to monitor the field performance of these newer tires.On May 22, 2001, Ford announced a program to replace all Wilderness AT tires installed on its vehicles. NHTSA encourages owners of all Ford vehicles with P235/75R15 and P255/70R16 Wilderness AT tires built after April 1998 to take advantage of the Ford program.

 

FORD EXPLORERS & FORD RANGER TRUCKS ROLL OVER WITH FIRESTONE AT TIRES

 

The rate of tread separation failures of Wilderness AT tires on Ranger pickup trucks is lower than their failure rate on Explorer SUVs. This is due to a variety of reasons, including the fact that the Explorer generally carries higher loads, and its tires had a significantly lower recommended inflation pressure, particularly on the rear wheels. Moreover, the likelihood of a crash due to a tread separation, and of deaths or injuries, is substantially lower on a pickup than on an SUV. Therefore, NHTSA's initial decision applies only to tires installed on SUVs. However, because the risk of future separations on pickup truck tires remain a cause for possible concern, NHTSA is pleased that Firestone will offer to replace these tires on pickup trucks at no cost to owners. See: Ford Ranger Rollover

Consumers with P235/75R15 and P255/70R16 Wilderness AT tires can determine whether their tires are covered by this action by checking the DOT serial number on the tires, which is located in the lower sidewall area directly above the rim flange. The tires are covered if the last number is "4," "5," "6," or "7." If the last number is "8," only those tires having 018 through 188 as the last three digits are included. Firestone dealers and retailers will also provide assistance in this regard.

 

WHY WERE FIRESTONE TIRES DE-TREADING (TREAD SEPARATION FAILURES) AND CAUSING ROLLOVER ACCIDENTS ON FORD EXPLORERS ?

 

The National Highway Traffic Safety Administration (NHTSA) has made an initial decision that a defect related to motor vehicle safety exists in certain P235/75R15 and P255/70R16 Firestone Wilderness AT tires manufactured before May 1998 that are installed on sport utility vehicles (SUV). This Engineering Analysis Report provides the basis for that decision.Belt-leaving-belt tread separation failures of ATX and Wilderness AT tires manufactured by Bridgestone Firestone, Inc. (Firestone), have led to numerous rollover, wrecks, crashes, injuries, and fatalities. In August 2000, Firestone determined that a safety-related defect existed in all Firestone P235/75R15 ATX tires and in Firestone Wilderness AT tires of that size manufactured at its Decatur, Illinois plant, and commenced a recall to replace those tires. Wilderness AT tires were the successor to ATX tires and are similar to them in many respects. NHTSA's Office of Defects Investigation (ODI) has conducted an extensive investigation to determine whether any other Wilderness tires contain such a defect, and whether they should be recalled as well.

 

The focus of ODI's investigation was on those non-recalled tires that are similar to the recalled tires; i.e., Wilderness AT tires of the size P235/75R15 and P255/70R16 manufactured by Firestone for supply to Ford Motor Company (Ford) as original equipment, as well as replacement tires manufactured to the same specifications ("focus tires"). Most of the focus tires were manufactured at Firestone's Wilson, North Carolina and Joliette, Quebec plants, beginning in 1994. In late 1998, Firestone began producing P255/70R16 Wilderness AT tires at Decatur, and in mid-1999, it began producing P235/75R15 Wilderness AT tires at a new plant in Aiken, South Carolina. Also, fewer than 100,000 P235/75R15 Wilderness AT tires were produced at Firestone's Oklahoma City, Oklahoma plant. The focus tires were predominantly used as original equipment on Ford Explorer SUVs and, to a lesser extent, on Ford Ranger compact pickup trucks, and as replacement tires for use on these and other SUVs and pickups.ODI's investigation included, with respect to both Firestone tires and peer tires, thorough analyses of available data regarding the performance of tires in the field; shearography analysis to evaluate crack initiation and growth patterns and their severity in tires obtained from areas of the country where most of the failures have occurred; and observations, physical measurements, and chemical analyses. ODI also reviewed numerous documents and extensive test data submitted by Firestone and others.

 

BELT-TREAD SEPARATIONS (WITH COMPLETE AIR LOSS OR PARTIAL AIR LOSS) BOTH CAN CAUSE ROLLOVERS TO OCCUR FROM LOSS OF CONTROL

 

Belt-leaving-belt tread separations, whether or not accompanied by a loss of air from the tire, reduce the ability of a driver to control the vehicle, particularly when the failure occurs on a rear tire and at high speeds. Such a loss of control can lead to a crash. The likelihood of a crash, and of injuries or fatalities from such a crash, is far greater when the tread separation occurs on a SUV than when it occurs on a pickup truck.

 Firestone tread separation claims included in the Firestone claims database involving the recalled and focus tires have been associated with numerous crashes that have led to 74 deaths and over 350 injuries (as of March 2001). Tread separation complaints from all sources included in the ODI consumer complaint database (including the Firestone claims data) that can be identified as involving these tires have reportedly led to 192 deaths and over 500 injuries (as of September 2001).

The belt-leaving-belt tread separations in the recalled and focus tires generally occur only after several years of operation. Thus, since the focus tires have not been on the road as long as the recalled ATX tires, the absolute number of failures of those tires, and the unadjusted failure rate of those tires, are less than those of comparable ATX tires. Claims in the Firestone claims database involving the focus tires have been associated with 17 deaths and 41 injuries, with additional crashes and casualties reported in the ODI complaint database, including reports of six additional fatalities. However, on a plant-by-plant basis, the focus tires manufactured at the Wilson and Joliette plants have exhibited tread separation failure trends that are similar to those experienced by the recalled ATX tires at similar service intervals.

These failure trends indicate that it is likely that, if they are not removed from service, the focus tires - at least those manufactured before May 1998 - will experience a similar increase in tread separation failures over the next few years, leading to a substantial number of future crashes, injuries, and deaths. The tread separation failure experience of the focus tires is far worse than that of their peers, especially that of the Goodyear Wrangler RT/S tires used as original equipment on many Ford Explorers.

 

COMPLETE BELT-TREAD SEPARATION OR BELT FAILURE OFTEN BEGIN AS BELT EDGE SEPARATION 

 

The belt leaving belt tread separations that have occurred and are continuing to occur in the recalled and focus tires begin as belt edge separation at the edge of the second, or top, belt. This is the area of highest strain in a steel belted radial tire and is a region with relatively poor cord?to?rubber adhesion because bare steel is exposed at the cut ends of the cords. Once belt?edge separations have initiated, they can grow circumferentially and laterally along the edge of the second belt and develop into cracks between the belts. If they grow large enough, they can result in catastrophic tread detachment, particularly at high speeds, when the centrifugal forces acting on the tire are greatest.

 

ODI conducted a non-destructive analysis of numerous randomly collected focus tires and peer tires from southern states, where most of the failures have occurred, using shearography, which can detect separations inside a tire. This shearography analysis demonstrated that the patterns and levels of cracks and separations between the belts were far more severe in the focus tires than in peer tires. Many of the focus tires that were examined were in the later stages of failure progression prior to complete separation of the upper belt. The shearography results for tires manufactured at Wilson were similar to those manufactured at Joliette.

 

A critical design feature used by tire manufacturers to suppress the initiation and growth of belt-edge cracks is the "belt wedge," a strip of rubber located between the two belts near the belt edges on each side of the tire. The belt wedge thickness, or gauge, in the ATX tires and the Wilderness AT tires produced prior to May 1998 is generally narrower than the wedge gauge in peer tires, and the wedge gauge in cured tires was often less than Firestone's target for this dimension. The tires with this wedge did not adequately resist the initiation and propagation of belt-edge cracks between the steel belts. During March and April 1998, Firestone changed the material composition and increased the gauge of the wedge in its Wilderness AT tires (and some other tire models).

 

Another important feature of radial tires related to the prevention of belt-leaving-belt separations is the gauge of the rubber between the two steel belts, or "inter-belt gauge." The inter-belt gauge initially specified by Firestone for the focus tires is generally narrower than the inter-belt gauges in peer tires and is narrower than Firestone's original specification for the ATX tires in the early 1990s. Moreover, the actual measured gauge under the tread grooves in several of the focus tires measured by ODI was far less than Firestone's minimum design specification. Since an inadequate inter-belt gauge reduces the tire's resistance to crack growth and its belt adhesion capabilities, this narrow inter-belt gauge may be partially responsible for the relatively low peel adhesion properties of the focus tires compared to peer tires. In August 1999, after becoming concerned about the adequacy of the inter-belt gauge in the cured Wilderness AT tires, especially in the regions directly under the tread grooves, Firestone changed the inter-belt gauge specification back to the original dimension.

 

Another relevant feature is the design of the shoulder pocket of the focus tires, which can cause higher stresses at the belt edge and lead to a narrowing, or "pinching," of the wedge gauge at the pocket. The focus tires exhibit a series of weak spots around the tire's circumference, leading to the initiation and growth of cracks earlier than in competitor tires and in other Firestone tires produced for light trucks and SUVs. In addition, many of the focus tires exhibited shoulder pocket cracking similar to that which Firestone identified as a significant contributor to the risk of tread detachment in the recalled ATX tires.

 

Because the tread separations at issue in this investigation occur only after several years of exposure, almost all of the failures on which ODI's analysis of field experience was based involved tires manufactured before the May 1998, when Firestone increased the dimensions and improved the material of the belt wedge. In theory, these modifications to the wedge would tend to inhibit the initiation and propagation of the belt-edge cracks that lead to tread separations. If these modifications actually improved the resistance of the focus tires to belt-edge separations, the historical failure trends described above may not predict the future performance of the newer tires. However, because tread separation failures rarely occur in the focus tires until at least three years of use, it is not now possible to ascertain from field experience whether their actual performance has improved significantly.

 

ROLLOVER RATE OF FORD RANGER LOWER DUE TO LOWER CARGO LOADS THAN THE FORD EXPLORER

 

The rate of tread separation failures on Ranger pickups is lower that the rate of such failures on Explorers for a variety of reasons, including the fact that the Explorer generally carries higher loads and is a more demanding application, and the tires on the Explorer had a significantly lower recommended inflation pressure (especially on the rear wheels). The risk of such a separation on Rangers remains a cause for possible concern. Nevertheless, because the likelihood of a crash due to a tread separation, and of deaths and injuries resulting from such a crash, is substantially lower when the separation occurs on a pickup than on a SUV, NHTSA's initial defect decision does not apply to focus tires installed on pickup trucks.

Under the National Traffic and Motor Vehicle Safety Act, in order to compel a manufacturer to conduct a recall, NHTSA has the burden of proving that a safety-related defect exists in the manufacturer's products. The record of this investigation supports a determination that a safety-related defect exists in the focus tires manufactured by Firestone prior to its 1998 modifications to the belt wedge that are installed on SUVs. Although the agency has concerns about the possibility of future tread separations in focus tires manufactured after the wedge change, the available evidence at this time does not clearly demonstrate that a safety-related defect exists in those focus tires. NHTSA will, however, continue to closely monitor the performance of these tires.

 

Therefore, on the basis of the information developed during the ODI investigation, NHTSA has made an initial decision that a safety-related defect exists in Firestone Wilderness AT P235/75R15 and P255/70R16 tires manufactured to the Ford specifications prior to May 1998 that are installed on SUVs. These tires were manufactured primarily at Wilson and Joliette and, to a lesser extent, at Oklahoma City. The initial decision does not apply to the P255/70R16 tires produced at Decatur or any of the Wilderness AT tires produced at Aiken, since these tires were all manufactured after May 1998.

 

Recalled Tires: Firestone Wilderness AT Tires, Firestone Radial ATX &  Firestone ATX II Tires and others...

Last August, Bridgestone/Firestone, Inc., the largest subsidiary of the world's largest tire and rubber manufacturer, recalled 6.5 million tires of a certain brand and size in North America. The recall was preceded by the U.S. government's investigation into hundreds of motor vehicle accidents resulting in death or serious injury, allegedly caused by tread or belt "separation" in these tires. Most accidents involved Ford Explorers equipped with the recalled tires.Based on recently released public information, it appears that many incidents of tread separation are attributable to poor manufacturing practices and quality control at certain tire plants. This information greatly bolsters manufacturing-defect claims involving tread separation. In addition, finger pointing by Firestone and Ford supports additional claims against these companies in tread separation cases, including design defect, marketing defect, and negligence claims.

 

On May 2, 2000, the National Highway Traffic Safety Administration (NHTSA) initiated a formal investigation into tread separation of Firestone Wilderness AT, ATX, and ATX II tires. These tires were original equipment on many Ford Explorers and other Ford sport utility vehicles and light trucks and were also available as replacement tires. At the time NHTSA initiated this investigation, the agency was aware of 90 incidents involving these tires, 33 of which resulted in crashes causing 27 injuries and 4 fatalities. These numbers increased dramatically over a short period of time. At press time, NHTSA had received over 2,000 complaints, including reports of over 100 fatalities. Most drivers reported that they were driving at highway speeds when "suddenly they lost control." In some of the crashes it was reported that the tread wrapped itself around the rear axle. NHTSA noted a "strong geographical trend," with most of the incidents occurring in the warmer-weather states.

 

FORD RECALLS FIRESTONE TIRES ON ITS VEHICLES - TOO MANY EXPLORER ROLLOVERS

 

Shortly after NHTSA began its investigation, it was discovered that Ford had already recalled Firestone tires on its vehicles in at least 10 foreign countries, where it said hot temperatures could make the tread separation problem worse. Ford was replacing these tires for consumers in Venezuela, Ecuador, Colombia, Saudi Arabia, Kuwait, Oman, Qatar, Basra, Thailand, and Malaysia.During the same period, numerous retailers, including Sears, Roebuck & Co., stopped selling these tires.Firestone announced the recall on August 9, 2000. The recall included all 15-inch Firestone ATX and ATX II models produced in North America and all 15-inch Firestone Wilderness AT models produced in the company's Decatur, Illinois, plant. Firestone made about 14.4 million of these tires. The company estimated that 6.5 million of the recalled tires were still in use, including 3.8 million Radial ATX and ATX II tires and 2.7 million Wilderness AT tires.

 

Firestone indicated that it would execute the recall in three phases, beginning with the warmer-weather states. The company said the recall would take one year to complete. By August 12, Ford began offering replacement tires for its vehicles with tires subject to the recall in the United States.

Shortly after the recall, concerns were raised about its scope. Consumer groups in this country and others questioned why the 16-inch tires of all the models were not recalled and why the Wilderness AT tires built in plants other than the Decatur plant were not recalled. It was discovered that in 1999 Ford recalled 16-inch Wilderness AT tires in Saudi Arabia, other Persian Gulf countries, and Venezuela. Further, there was evidence that some of Firestone's other plants experienced manufacturing problems similar to those experienced at the Decatur plant. On September 1, NHTSA issued a "consumer advisory" for an additional 1.4 million Firestone tires that were not covered by the recall, noting that tread separation rates for the additional tires exceeded those for the recalled tires, sometimes by a large margin.Firestone's and Ford's problems with government agencies were not limited to products sold in the United States. In late August, the Venezuelan consumer protection agency released a report indicating that it had enough evidence to proceed with criminal charges against Firestone and Ford. Ford announced that Firestone had failed to include a nylon overlay in the Venezuelan tires that could have reduced the tread separations that led to hundreds of accidents and many fatalities. Firestone, however, maintained that Ford recommended tire pressure that was too low for driving conditions in that country.

 

According to Firestone, it built the tires to Ford specifications, which did not include a requirement for nylon overlays. Ford charged that Firestone agreed to include the nylon overlays in tires manufactured in Venezuela but failed to do so. Ford further asserted that Firestone mistakenly labeled the tires to indicate that they contained nylon overlays.Ford has continuously maintained that the problem is exclusively related to the Firestone tires. Firestone, on the other hand, blames Ford for recommending an excessively low tire pressure.

 

On September 6, the chief executives of Firestone and Ford testified before the U.S. Congress. Masatoshi Ono of Firestone offered an apology, stating he accepted "full and personal responsibility" for the events leading to the hearings, but reiterated the company's defense that drivers are to blame for the accidents Jacques Nasser, Ford's chief executive, placed the blame on Firestone. He said that Ford did not learn of the tire problem until the company "virtually pried the data from Firestone's hands and analyzed it ourselves."During the hearing, committee members accused Firestone and Ford of conducting a cover-up at the expense of people's lives by failing to notify U.S. safety officials sooner about the problem.13 Both Ono and Nasser promised to furnish the congressional committee with additional information.