have focused attention on unsold new tires being put into service long after their "best-before" date. In reality, there is no official best-before date for light-duty tires - nor for heavy-duty truck tires.
This tempest in a teacup began when ABC's "20/20" investigative reporter, Brian Ross, filed a story suggesting that older tires - anything over six years of age - were sold as brand new in tire shops all across America. Ross suggested in as many words that these tires were little more than ticking time bombs.
A similar report, "Expired Tires" on NBC, highlighted an alleged tire failure that claimed the life of a 20-year-old Florida man. The tire in question was said to be a spare tire that had been installed on the car just three days prior to the accident.
Video footage showing the tread on the accident tire led me to believe that tire had plenty of miles on it prior to the incident. And at no time during either of the two network news stories was there any discussion about the speed the vehicle was traveling at the time of the incident, or what the tire inflation pressure might have been. Both or either could easily have contributed to the type of failure illustrated in the video.
The tail end of the NBC report revealed that the tire in question had been included in an earlier major recall, and that it should have been pulled from service by the previous owner of the accident vehicle.
Is there, or should there be, concern over aging truck tires? The tire experts we look to frequently here at Heavy Duty Trucking say the answer is no. Getting a million miles of service over a decade or more (with several retreads) isn't uncommon for premium truck tires these days. That's what we've come to expect from premium tires, and that's about what premium tires should deliver - assuming they have been well maintained and skillfully retreaded.
Peggy Fisher, president of Tire Stamp and a highly regarded tire expert and lifelong participant in tire-related activity within the Technology and Maintenance Council, says it's wrong to lump heavy truck tires in with passenger and light truck tires in this context.
"There is no comparison. These tires are built entirely differently than passenger and light truck tires," she says. "Medium and heavy-duty truck tires are designed to run 1 million miles today. That means they have to be retreaded several times, and could take up to 10 years or more to run this many miles."
Absence of Evidence
Both of the aging-tire "exposés" allege the practice of selling expired tires is rampant across the U.S. Both networks sent undercover camera crews out to buy tires at various dealerships, and both reported being able to buy old tires from stock at several tire dealers - some as old as 12 years. New, unused tires sitting in stock for more than 10 years suggest there's an inventory management problem at some of these dealers, or the tires they found and bought were odd sizes or special-order stock that never sold. The reports never made that clear. (While the investigative reports never asked the question, you have to wonder why a tire would sit in inventory that long if stock was being regularly rotated and moved through the supply chain.)
But that still doesn't answer the questions of whether or not old tires are actually a safety hazard.
Appearing briefly on both reports, Dan Zielinski, vice president of communications with the Rubber Manufacturers Association, said there's no scientific information that points to when a tire should be removed from service solely because of its age. RMA believes there are too many variables to set a timeline for tire expiration.
"Tires are not milk. Milk will go bad in maybe 10 days or so. Tires [and] their performance are affected by a number of issues," Zielinski said in the NBC report. "Right now there is no information that points to a specific date when tires will no longer be able to perform solely due to age."
Jim Davis, public relations manager at Goodyear Tire and Rubber, agrees. He says that while the age of a tire really isn't a key factor, tire care, maintenance, and general condition of the tire are factors that will affect performance and service life.
Still, Ford Motor Company and DaimlerChrysler (as the company was then known) added tire-age advisories to their owners' manuals in 2005 suggesting older tires be taken out of service after six years regardless of the mileage. Several German automakers and Toyota have had similar warnings in place since the 1990s.
All that information and much more about age-related degradation is summarized in a document titled, "Tire Aging Tests, Data and Policies Continue to Emerge," copyrighted in 2006 by Safety Research & Strategies. SRS is a research enterprise with tight ties to several law firms specializing in product liability litigation - which would go a long way toward explaining the hype surrounding aging tires.
Truck Tires are Different
Twice during ABC's report, a shot of a peeled truck tire tread lying at roadside flashed on screen. Nothing different from any of the thousands of "alligators" we see at roadside every day, but the shot and the narrative posed a suggestive question: Maybe aging truck tires are equally dangerous?
That's highly unlikely, says Goodyear's Davis.
"The aging tire dialogue has so far been confined to consumer tires," he says. "It just doesn't apply to heavy truck tires. The difference is the extent to which truck fleets manage and look after their tire investment. The key is consistent care."
As noted earlier, there was no discussion of inflation pressure or vehicle speed in the TV reports. There isn't a self-respecting fleet manager in the country who could argue that inflation pressure isn't the chief cause of much of the tire debris found at roadside today. Failures resulting from pressure-related sidewall failures and tread separations are well documented and well understood. Fleets are making substantial investments in pressure monitoring technology and inflation systems to combat the problem (more on that next month).
Still, those same self-respecting fleet managers will probably tell you there is a correlation between a tire's age and its failure rate. Simply put, says Fisher, older tires do fail at a higher rate than brand new tires, because they have had more opportunity to be run underinflated, overloaded, abused, and damaged over the course of their lives.
"Tires build up and accumulate a heat history caused by all of the above, and this fatigues and eventually fails tires. However, if a truck tire is maintained properly, there is no reason why it cannot live to a ripe old age of let's say 10 years, be retreaded several times, and run a million miles," she notes.
How's 10 years for a best-before date? For the price, you won't find may other components with the level of stress and exposure a tire undergoes lasting better than a decade.
From the May 2009 issue of Heavy Duty Trucking.