Sean Kane and the staff of SRS have been advocating for consumers in the tire safety arena since the Ford Explorer/Firestone Wilderness ATX tire catastrophe of the late 1990s. Kane’s investigation uncovered Ford’s secret recall of Firestone tires on Explorers in Venezuela which they failed to disclose to U.S. government investigators. Public disclosure of his findings became a watershed moment leading Ford and Firestone to announce a recall days later in the U.S.
Our firm has regularly submitted comments to National Highway Traffic Safety Administration dockets on making the Tire Identification Number accessible and easy-to-understand, on tire age and on improving the tire recall system.
Our comments to NHTSA’s tire age docket included background on the little-known warnings in owner’s manuals that tires older than six years posed dangers and identified important manufacturer’s reports and studies, including the BRMA recommendation, which had previously been suppressed from the public. We have testified before or supported the work of state legislative committees considering tire age legislation. We have petitioned the agency to take a higher profile on the dangers of tire age. For example, in June 2008 NHTSA issued a Consumer Advisory warning the public about the dangers of tire aging, after SRS began lobbying the agency to educate the public, beginning in 2003. We have requested automakers to adopt tire aging guidelines.
In the absence of any existing database documenting tire age in crashes in which a tire was a causal factor, SRS conducted original research. Our findings thus far, submitted to NHTSA in 2012, have identified 252 incidents in which tires older than six years experienced tread / belt separations—most resulting in loss-of-control and rollover crashes. These incidents were the cause of 233 fatalities and 300 injuries.
SRS continues to document the scope and magnitude of the tire aging problem as well as its investigation into what is known and when it was known about this danger. For a more complete accounting of our advocacy efforts, including docket submissions and letters to manufacturers, see SRS Advocacy on Tire Safety.
Tires Age Dangerously
Tires, like any other rubber product, have a limited service life regardless of tread depth and use. This unremarkable fact has been long-acknowledged by automakers and some tire manufacturers. Yet, the public, and even tire retailers and service technicians, know little about the dangers of aged tires. Aged tires are often unsuspectingly put into service after having served as a spare, stored in garages or warehouses, re-sold on the used tire market or are simply used on a vehicle that is infrequently driven. In many instances these tires show no visible sign of deterioration, and absent any visible indicators, tires with adequate tread depth are likely to be put into service regardless of age.
The phenomenon of tire age degradation or thermo-oxidative aging has been documented in technical papers going back more than 80 years, and according to one journal article from 1931, it wasn’t news then: “The auto-oxidation of rubber has been known for a long time, and for a long time, too, it has been known that it plays an important part in spontaneous deterioration or aging, and it has been the object of numerous studies of much interest.” In 1929, the Journal of Physical Chemistry published a technical paper of the absorption of oxygen by rubber, noting that oxygen aged rubber, and that an artificial aging test was needed not only to “accurately foretell the natural life of rubber goods, but also for the development of rubber compounds of superior aging qualities.”
Today’s concerns about tire age began to emerge about thirty years ago, in part, because the new radial tires lasted significantly longer than the old-style bias-ply models and the early radial designs of the 1970s and 1980s. In 1985, Uniroyal authored one key paper on tire “long-term durability.” Presented at the International Rubber Conference, Kyoto, Japan, the paper acknowledged that tire age had “long been a concern for radial tires” and that government required short-term durability testing is done “without any consideration of chemical reaction, which would happen in long-term service
Safety Research & Strategies Tire Aging Animation
Two independent studies in Germany, using different data sets, concluded that tires failed at a greater rate after six years and recommended manufacturers alert consumers in an effort to prevent potential crashes. In 1989, ADAC, Germany’s consumer advocacy counterpart to Consumers Union and AAA in the U.S., tested 23 unused spare tires ranging in age from five to 12 years old, in a high-speed bench test to determine the level of safety reserves over time. Although the test sample was small, the organization concluded: “Even tires that are just six years old – though they appear to be brand new – can present a safety risk. Tire experts even say that if they are not used, indeed, tires age more quickly.”
Overseas, the rubber industry’s acknowledgement of material degradation aging eventually evolved into the concept of an expiration date for tires. European and Japanese vehicle manufacturers including BMW, Audi, Volkswagen, Toyota, and later Mercedes-Benz, Nissan, and GM Europe, among others, included warnings to consumers in their owner’s manuals that tires older than six years should only be used in an emergency and replaced as soon as possible.
Many of these warnings, which were added beginning in 1990, were also included in U.S. owner’s manuals. For example, GM’s European divisions Opel and Vauxhall added warnings to their owner’s manuals as early as 1991: “Tyres age even if they are used only very little or not at all. A spare wheel which has not been used for six years should be used only in emergencies; drive slowly when using such tyres.” Other warnings, such as those in Volkswagen’s 1992 owner’s manuals were more pointed: “WARNING – Tires age even if they are not being used. Tires which are older than 6 years old should only be used in an emergency and then with caution.”
In the U.S. it took the Ford Explorer/Firestone Wilderness ATX scandal to push tire aging to the front burner. In the 1990s, America’s most popular and best-selling SUV, the Ford Explorer, equipped with their original equipment Firestone tires, was prone to fatal rollovers after tread separations at highway speeds. The Firestone Radial ATX and Wilderness radial tires met all of the federal regulations at the time. Those standards, however, were written when bias-plies were the norm. There were no federal standards for occupant protection in rollovers and there was no minimum stability standard for Sport Utility Vehicles. Industry fought off any regulations, even as the rollover death tolls in light trucks rose to epidemic levels.
Then a series of gruesome high-profile crashes and news stories about the safety of Ford Explorers and Firestone tires triggered Congressional hearings. The Transportation Recall Enhancement, Accountability and Documentation (TREAD) Act in 2000 compelled NHTSA to re-write the tire standard and to examine tire aging. While the agency embarked on a tire-aging research and rulemaking, rubber manufacturers overseas were again translating their knowledge of tire aging into policy.
In June 2001, the British Rubber Manufacturers Association (BRMA), which represents the same tire manufacturers in the U.S. market, issued a recommended tire aging practice:
“BRMA members strongly recommend that unused tyres should not be put into service if they are over 6 years old and that all tyres should be replaced 10 years from the date of their manufacture.”
The recommendation noted that environmental conditions like exposure to sunlight and coastal climates, as well as poor storage and infrequent could accelerate the aging process. Aging, the BRMA said could be identified by small cracks in the tire sidewall, however, “‘aging’ may not exhibit any external indications and, since there is no non-destructive test to assess the serviceability of a tyre, even an inspection carried out by a tyre expert may not reveal the extent of any deterioration.”
And yet, there was no such recommendation emanating from the Rubber Manufacturers Association in the U.S. Instead, the RMA was fighting NHTSA’s attempts to regulate tire age. In 2002, NHTSA proposed a tire aging test, only to be met with overwhelming industry opposition. The agency withheld further rulemaking and began additional research.
The Ford Motor Company, however, conducted its own research into the material science behind tire aging. Led by former 3M materials scientist Dr. John Baldwin, the Ford team conducted a methodical evaluation of thermo-oxidative aging and its effects on radial tires, and developed more precise tire age test methods. Ford’s conclusions, published in peer-reviewed journals, were based on a series of detailed analyses of field-aged tires. Baldwin’s team devised artificial aging techniques to replicate field aging, and tested tires to failure to determine the effects of age.
The National Highway Traffic Safety Administration (NHTSA) also tested and analyzed field-aged tires and reached similar conclusions in 2006. The American Society of Testing and Materials (ASTM) working group on tire age, which consists of tire, rubber, and vehicle manufacturer’s representatives, also replicated these findings.
The most significant data that links tire age to failures was cited in the August 2007, NHTSA’s Research Report to Congress on Tire Aging. In 2005, a provision in the Safe Accountable, Flexible and Efficient Transportation Equity Act required the agency to report to Congress by August 2007 on tire aging, including potential regulatory testing to evaluate the risk of failure after a tire has been aged. The agency reviewed insurance company tire claims reported from 2002 through 2006 and found 77 percent of the tire claims came from five hot-climate states (including California) and 84 percent of these claims were for tires more than six years old. This is the strongest published evidence to date of the link between tire age and tire failures.
And yet, this strong, contemporary research – following in the footsteps left by rubber material scientists more than three-quarters of a century before – have yet to translate into federal regulations, an industry consensus on policy and best practices or consumer or tire technician education. What the U.S. has seen is the slow spread of warnings in owner’s manuals and internal recommendations. In early 2005, Ford concluded that it needed to issue a 6-year replacement “recommendation” for tires, regardless of tread. The warning was placed on their website and appears in all of their 2006 owner’s manuals. DaimlerChrysler also added the 6-year warning.
In October 2005 Bridgestone/Firestone broke ranks with other tire makers and issued a “Technical Bulletin” to its dealers advising them that tires should be inspected after 5 years and replaced after 10 years – “even when tires appear to be usable from their external appearance or the tread depth may not have reached the minimum wear out.” Michelin and Continental issued similar bulletins in February 2006. Hankook joined the chorus in 2009. Most – including Bridgestone/Firestone – were actually recommending a 6-year shelf life for tires, because the tiremakers’ tire age warnings defaulted to the individual vehicle manufacturers’ recommendations. Automakers had, by and large, opted for a six-year tire age recommendation.
In June 2008, the National Highway Traffic Safety Administration has issued its first consumer advisory that addressed the dangers of aged tires. The agency was under increased pressure to address consumers following the recent high-profile stories on tire aging on NBC’s Today Show and an investigative report on ABC 20/20. A Congressional hearing on rollover safety – a potential forum for Congress to ask NHTSA what it planned to do on tire aging – was also looming. The Consumer Advisory, released the day before the hearing, kicked off the summer driving season. The all-purpose warning for motorists to check their tires – including the spare – for signs of wear, under-inflation and age, was an important public acknowledgement of a safety hazard the agency has long understood. While NHTSA’s Consumer Advisory did not define any tire age limit, it did refer to vehicle and tire makers age recommendations.
“Some tire and vehicle manufacturers have issued recommendations for replacing tires that range from six to ten years of age. Consumers are advised to check with their tire or vehicle manufacturer for specific guidance.”
Rulemaking that would require a tire aging test has stalled out. Ford, which sponsored and published so much research on tire aging, doesn’t appear to educate its own dealerships, service writers or service technicians about tire age. Ford has not issued technical service bulletins, or service information, or included information about the hazards of tire age in Ford technician training materials, in the curricula at technical schools offering Ford affiliated programs or in communications with Ford dealership service writers.
Today, used car dealers sell older vehicles with old tires, tire techs are still rotating aged, unused spares into service; you can purchase very old “new” tires at retailers, including Sears and Walmart. In June 2008, one broadcast journalist in Kansas City, Missouri went undercover with an 11-year-old tire and a concern about the tire being under-inflated to see if tire technicians would notice its age – or if they would even be able to read the Tire Identification Number molded on the sidewall to determine its date of manufacture. Nine out of ten service techs at some of the nation’s largest tire retailers—including Walmart—were unable to identify the hazard or the correct age. Few tire retailers would agree to address the failures of their own personnel to the report. Wal-Mart issued a statement in response: “We follow manufacturers’ guidelines and provide our TLE associates training in regards to general tire safety. We recommend that customers concerned about the age or condition of their tires have them inspected by a tire professional.” Sears conceded: “Our technician should have recommended that the customer go to the consumer relations section of the tire manufacturer’s website for more information about specific tires and we plan to retrain our auto center technicians on appropriate procedures going forward. Also, to assist customers with tire recalls, Sears will now post the customer relations numbers of major tire manufactures on our website.”
But little has changed. Consumers continue to purchase and use aged tires, because there isn’t a law or an industry agreement to ensure that doesn’t happen.