As the old adage goes, “there’s a lot riding on your tires.” Many of the safety advances made in recent years, such as Antilock Brakes and Electronic Stability Control are dependent upon good interaction between the vehicle and the road surface. When the tire fails, these safety advances are lost or greatly diminished. The tires on your car or truck are the only contact between your vehicle and the road, and when it comes to vehicle safety, nothing is more important.
Tire failures can result from a design or manufacturing defect, or the tire may simply be too old to withstand the heat and pressure of the road, regardless of remaining tread depth. The recall of defective Firestone Tires brought the tread separation and belt adhesion issues into the public spotlight, resulting in heightened public awareness and, no doubt, countless lives saved. In the course of our everyday lives, we carry our family, our friends, and business associates in our vehicles, so knowledge of potential tire defects is critical to safety on the road.
The dangers of “aged” tires, while beginning to come more into public view, remain a little known problem outside of the industry and one that could be the cause of a significant number of tread separations. Aged tires are often unsuspectingly mounted on a vehicle after having served as a spare, being stored in garages or warehouses, or simply having been used on a vehicle that is infrequently driven. In many instances these tires show no visible sign of deterioration, and absent any visible indicators such as dry rot, tires with adequate tread depth are likely to be put into service without consideration of age.
The physical and chemical properties of the rubber and other components in tires change over time, regardless of use. Studies show that tire performance can start to degrade after six years, leading to a greater risk of separation – even if the tire hasn’t been used at all. According to the Massachusetts auto-safety research firm Safety Research Systems, Inc. (SRS), as of June 2008, at least 159 accidents have been linked to tread separation of tires more than six years old, which resulted in 128 fatalities and 168 injuries. An additional 10 cases involving tires older than five years at the time of failure have also been documented by SRS, accounting for an additional 14 fatalities and 24 injuries.
NHTSA is conducting tests on new tires to determine their durability and developing future tests to simulate aging. The agency has said it will begin requiring manufacturers to print the manufacture date on tires in September 2009. Currently, the manufacture date for a tire can only be determined by decoding the DOT number stamped into the tire’s sidewall. Most drivers and tire consumers don’t know how to do this, and further, don’t appreciate why the tire age could be significant in the first place. The makers of BMW, Ford, Lincoln, Mercury, Chrysler, Toyota, Mercedes, Jeep, Lexus, Audi, Bentley and Volkswagen vehicles have all backed guidelines that tires should only be in service six years.
Tire Tread Separation
The tires on your car are a product designed to wear out before they fail because of the serious dangers posed by tire failure. When a radial tire suddenly loses its tread, the driver often loses control of the vehicle. A blowout of the tire, or rapid pressure decrease in the remaining core, is often associated with a loss of tire tread and drastically increases the chance of a rollover accident. As seen in the Firestone Tires that were widely recalled in 2000, tread separation occurred due to adhesion problems between the steel and rubber in steel-belted radial tires.
The treads may separate because of a defect that occurred in either the manufacturing or the design process for that tire. For example, the fusing which occurs during vulcanization may not have fused completely or properly. Time and the physical changes the tire undergoes over time also reduce the effectiveness of the bonding and adhesion of the tread to the tire, thus facilitating a tread separation.
How Old Are They Really?
The age of a tire is not readily apparent to the uninformed eye. Many consumers will see a tire and think that it looks brand new, and mistakenly associate the new appearance with recent manufacture. However, the actual manufacturing date of the tire may be quite different from the purchase date. Tire age degradation has been an “open secret” within the tire industry for years, and in June 2008 NHTSA finally issued a warning for consumers regarding the hazards of aged tires. This warning stated that even though tires may appear to be brand new, they can lead to “catastrophic failure.” The warning includes steps the consumer can use to determine a tire’s age, since the DOT code on the tire is a “consumer unfriendly” formula as opposed to a simple date stamp. It states that the age of the tire can be determined by locating the identification number on the sidewall that begins with the letters “DOT”. The last four digits represent the week and year the tire was manufactured.
To be certain that the tires on their family vehicle are not more than six years old, consumers cannot rely on the purchase date of the tire, and instead must decode the DOT number. In May of 2008, a group of reporters in California set out to see how old the “new” tires that were being sold really were. They found several retailers selling new tires that were in actuality up to twelve years old. The average consumer is completely unaware of the risk these tires can pose them themselves and other motorists.
Safety experts and NHTSA have taken the position that tires that are over six years old can be “catastrophic.” This is true even if the tire has not been in service for all of those years. The dangers of a tread separation, which could cause vehicles to lose control and crash or roll over, are very serious. Litigation is ongoing against tire manufacturers and retailers for manufacturing and design defects as well as for tread separations because of tire aging. Keep your family and other passengers safe by routinely checking the tread depth and air pressure of your tire and, until changes are made within the industry, learn to decode the DOT code on your tires to determine accurate age, and replace tires before they are six years old.
Id. (noting the effects of the change in chemicals over time on the effectiveness of the bonding of the tire layers together).
 Joseph Rhee, New Warning: ‘Catastrophic Failure’ Discovered in Aged Tires, ABC News, http://abcnews.go.com/print?id=4988518 (June 3, 2008).
Id. This “code” is likely just another way to keep consumers in the dark on how old the tires they are purchasing as “new” really are.
 Asa Eslocker & Joseph Rhee, ABC News Hidden Camera Investigation: Aged Tires Sold as ‘New’ by Big Retailers, ABC News, http://abcnews.go.com/print?id=4822250 (May 9, 2008).