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Doug Sharpe
President of Elasto Proxy

Did you drive to work today? Maybe you carpooled, or traveled by van or bus instead? If your method of transportation was a motorized vehicle with tires, you may want to track a rubber-related investigation by the National Highway Safety Transportation Board (NHSTB). Earlier this year, the independent federal agency launched an inquiry into two tire-related incidents that resulted in injuries and loss of life.

First, the NHSTB announced it was investigating the fatal highway crash of 15-passenger van in Florida. The incident occurred when the driver lost control of a 2002 Ford E350 XLT after the tread separated from the left rear tire, a two-year old BF Goodrich model that was part of a product recall initiated by the U.S. tire maker.

Next, the independent agency announced a probe into an incident involving a 10-year-old Michelin tire that was not the subject of a product recall. The Lousiana accident claimed four lives and injured 36 when the driver of a 2004 Kia Sorrento lost control and collided with a school bus. In that crash, the Kia’s left rear tire suffered sidewall separation and rapid air loss.

Do Tires Have an Age Limit?

According to ABC News, the NHSTB’s inquiry into these “tire-initiated events” is the first of its kind. The investigative agency will analyze numerous factors, but tire age-degradation is a special focus because of the accident involving the 10-year old tire. According to Don Karol, the NTSB’s lead investigator for this initiative, “aging does potentially play a role in the degradation of the internal structure of the tire”.

Sean Kayne, a safety consultant who testifies on behalf of plaintiffs in tire-related lawsuits, agrees. He also criticizes the tire industry’s opposition to date codes for tires. “They did not want to give the impression that tires might have a service life,” Kayne says. For “a universal practice that inherently keeps you safe,” he adds, replacing tires that are more than six years old is “a good place to go”.

Dan Zielinski of the Rubber Manufacturers Association (RMA), an industry trade group for tire makers, disagrees. Arguing that the six-year limit is “arbitrary”, Zielinski says “it’s more important how a tire is used, whether it’s maintained, and how it’s stored”. The RMA’s Executive Director opposes legislation that would establish age limits on tires, and is lobbying against mandatory inspections of tire age.

Cracking the Code

For motorists who wonder if there’s a way to determine the age of their vehicle’s tires, the code that Sean Kayne mentions holds the key. Located on the wall of your tire, this four-digit identifier contains two sets of numbers. The first two digits indicate the week, and the second two digits indicate the year. So a tire with a date code of 2108 was manufactured in the 21st week of 2008 – making it 6 years old.

Would you feel safe in a vehicle with six-year old tires? Should tires have an expiration date, even if they’ve never been used, to avoid tread separation and accidents like the ones in Florida in Louisiana? Alternatively, do you believe that a six-year age limit is arbitrary, and that motorists need to consider how a vehicle’s tires are used, stored, and maintained?

Before answering these questions, consider that there are several types of rubber in your tires. As I explained in What if Your Tires Could Talk? Rubber Compounds and Resistance, EPDM is used for the sidewalls because it resists ozone, which can attack stress points. SBR provides good traction in the tire’s tread, and BR rubber provides great abrasion resistance along with good cut and tear properties.

How Can We Help You?

Elasto Proxy doesn’t manufacture tires, but the company that Donna Sharpe and I founded 25 years ago does custom-fabricate industrial rubber products such as specialty seals and custom insulation. Do you have questions about how rubber ages, or how a rubber part’s usage and storage can affect its service life? Do you need help choosing the right type of rubber for your specific application?

Please contact us for more information, or join the conversation about safe tires on our social media channels. Look for a post with a link to this blog entry on LinkedIn, Facebook, Google+, and Twitter. Elasto Proxy has a YouTube channel, too. Finally, please subscribe to our free e-newsletters. They’re a great source of information delivered right to your email inbox, and they provide links to blog entries like this one.