After Long Delay, NHTSA Issues Advisory Addressing Tire Aging

WASHINGTON, D.C. – Eight years after the Explorer/Firestone rollovers pushed the problems of tire aging to the fore, the National Highway Traffic Safety Administration has issued its first consumer advisory that addressed the dangers of aged tires.

On June 2, NHTSA released the advisory as a kick-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.”

The advisory also reminded motorists that summer heat, especially in hot climates, can take its toll on worn, old or improperly inflated tires leading to tread separations, crashes and rollovers.

Internally, the agency has been studying the effect of age on tire robustness for at least seven years. NHTSA’s own investigation into Firestone ATX / Wilderness tire defects found that tires were failing predominantly after several years of service and that age was a factor particularly in the high ambient temperature environments, because the rubber becomes less resistant to fatigue crack growth with aging, thereby increasing the risk of failure. In a 2003 presentation, the agency noted there was general agreement within the industry that older tires are more likely to fail than newer tires – and simply that “tire age matters.” More recently, the agency’s Research Report to Congress on Tire Aging cited its analysis of insurance company tire claims reported from 2002 through 2006. The analysis found 77 percent of the tire claims came from hot climate states and a whopping 84 percent of these claims were for tires more than six years old.

Safety Research & Strategies has been advocating for the agency to issue a tire age advisory since 2004 and continued push NHTSA to provide meaningful information to the public. SRS’ comments noted “consumers and tire dealers need information and guidelines about the increased, and often invisible, risks presented by aged tires. . . Many of the cases we’ve reviewed show due care was exercised by the vehicle owner and even the tire service technicians; however, absent guidelines and information about the risks results in preventable tragedies.” SRS reiterated its request in its May 2 comments to the Tire Age docket and submitted a list of 159 incidents in which tires older than six years experienced tread / belt separations-most resulting in loss-of-control crashes. These incidents were the cause of 128 fatalities and 168 injuries.

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. Adding to the pressure was the June 4 Congressional hearing on rollover safety which gave Congress a forum to ask NHTSA what it planned to do on tire aging. The Consumer Advisory was sent out the day before the hearing.

Some German vehicle manufacturers and Toyota have included warnings buried in owner’s manuals for nearly 20 years following several studies in the late 1980s that found a disproportionate rise in failures once tires reached six years old. During the next ten years, others added similar warnings. The Firestone-Ford catastrophe and the Tire Recall Enforcement, Accountability and Documentation (TREAD) Act forced

NHTSA to examine tire aging issues. 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.

Tire manufacturers in the U.S. reluctantly joined the chorus in October 2005, when Bridgestone-Firestone specified that all tires should be removed after 10 years regardless of the remaining tread depth or that motorists follow the vehicle makers’ recommendations (i.e., six years). Continental, Michelin, and Cooper followed suit and issued Technical Bulletins on tire aging early in 2006.

The NHTSA advisory raises the bar says SRS president Sean Kane. “Increasingly manufacturers, distributors, retailers and service providers are going to have to address tire age. It’s getting harder and harder for the industry to deny this hazard and the advisory is another significant step toward solutions.”

Copyright © Safety Research & Strategies, 2008