Recent news reports about old tires failing has experts asking if tires should have expiration dates the same as many other products. Why? Because old tires are failing and killing people!
In a letter released September 22, 2003, a private safety group called Strategic Safety asked the National Highway Traffic & Safety Admin. (NHTSA) to investigate the problem of tire aging. The group says they have documented at least 20 accidents caused by old tires blowing out, 10 of which resulted in fatalities. Most of the lawsuits involving these tread separation accidents have been on tires that were six or more years old.
The group says the NHTSA should have a new rule requiring tire manufacturers to put expiration dates on all new tires.
The group also says tire retailers should NOT sell tires that have been in storage for more than six years since the date of manufacture.
Tires deteriorate over time, even if they are not used or driven on. The tires may appear to be in like-new condition on the outside, but inside the rubber is slowly deteriorating. This may dangerously weaken the tire and increase the risk of a blowout at high speed or during hot weather.
In one such incident, the owner of a 1964 Sunbeam Tiger was returning from an antique car show. The tires only had 4,000 miles on them and looked good as new on the outside, but the tires were 11 years old. On the way home, one of the tires blew out causing the car to crash. The passenger suffered permanent brain injuries as a result of the accident.
The Rubber Manufacturers Association, to which tire manufacturers belong, has responded by saying tire expiration dates may be hard to determine because there are so many variables that affect tire aging. "It's not so simple to just slap a date on it," said Dan Zielinski, a spokesman for the Rubber Manufacturers Association.
Zielinski said a discussion of expiration dates would be worthwhile, but said NHTSA should not act without collecting some solid scientific evidence. Zielinski said tire manufacturers worry that consumers wouldn't pay any attention to the an expiration warning anyway and would not replace old tires with new ones. "People might think, 'Here's the tire industry trying to get us to buy more tires by stamping a date on them,'" he said.
NHTSA issued new tire performance standards in June 2003 but put off an aging test because experts couldn't agree on how to conduct such a test. NHTSA spokesman Rae Tyson said the agency hopes to have a new proposal on tire aging at some point in the future.
Tire makers say expiration dates would complicate their distribution systems because new tires often sit on shelves for two years or more. They also say tires vary in chemical makeup, so one expiration date would not fit all tires. The National Highway Traffic Safety Administration says additional research is needed to come up with an appropriate aging test for tires.
How old are the tires on your vehicle? The date of manufacture is indicated by the last group of digits in the DOT manufacture code on the sidewall of the tire. The number is often stamped in a recessed rectangle. The DOT code tells who manufactured the tire, where it was made and when. The last group of digits in the code is the date code that tells when the tire was made.
Before 2000, the date code had three digits. Since 2000, it has had four. The first two digits are the week of the year (01 = the first week of January). The third digit (for tires made before 2000) is the year (1 = 1991). For most tires made after 2000, the third and fourth digits are the year (04 = 2004).
In the photo above, the date code is 8PY806. The 8PY is a manufacturing shift code, and the date the tire was actually made was 0806, which is the 8th week (08)in the year 2006 (06).
The date of manufacture is essential information for car owners and tire buyers because tires deteriorate even if they are not used. European automobile manufacturers recommend replacing ANY tire that is more than six (6) years old, including the spare tire. No such recommendations have yet been made by domestic vehicle manufacturers.
Tires have wear bars (flat spots)in the tread grooves to visually indicate wear. If the tread is worn down so the wear bars are flush with the surrounding tread, the tire is worn out and needs to be replaced. If you see cords showing through the rubber, the tire is unsafe to drive on and is on the verge of failure. Replace the tire without delay! The same advice goes for any tire that has bulges, deep cracks or the tread is separating from the casing.
Tread wear can be measured using a penny. Place the penny with Lincoln's head upside down in a groove between the treads. If you can't see the top of Lincoln's lead, the tire is okay and still has some wear left in it. But if the top of Lincoln's head is flush with the tread, the tread depth is 2/32-inch (1.6mm) or less, indicating the tire is worn out and needs to be replaced.
Some experts now say the same test should now be done with a quarter. If the top of Washington's head is flush with the tread when you place a quarter upside down in a groove, the tread depth is 4/32-inch (3.2mm). Though the tire still has some tread wear left, braking, traction and handling are significantly reduced compared to a tire with more tread on it. Because of this, many experts now recommend replacing tires when the tread depth is worn down to 4/32-inch or less.
Officials at the National Highway Traffic Safety Administration (NHTSA) believe that they have developed a test for determining the durability of aged tires. It reportedly involves subjecting a tire to high temperatures (up to 150 degrees Fahrenheit) for 8-to-10 weeks in a high oxygen environment. The test was given a stamp of approval by The Aged Tire Durability Task Group, a 33-member task force which includes representatives for tire makers, the auto industry and safety groups. The Task Group was formed in 2002 to establish a tire durability test. The Task Group also endorsed its own, separate durability test that would run tires at about 75 miles an hour for more than 30 hours.
NHTSA is required to report its tire durability test findings and recommendations to Congress by August 2007. At issue is the claim that some rubber compounds degrade over time, even if unused. NHTSA has been in the process of studying the topic but has found that it may be difficult to establish a uniform time limit that does not take into account other contributing aging factors such as climate, handling and storage. Several auto companies are backing a 6-year tire expiration date and a number of safety advocate groups are urging NHTSA to institute a regulation.
While supporting tire expiration research, SEMA believes it is important that regulators and lawmakers have the best science available before making any decisions on this topic. They should also consider the associated environmental, social and economic costs if expiration dates lead to premature tire scrapage. If a regulation were proposed, SEMA would likely seek a provision that exempts limited production tires (15,000 or less annually) and other specialized tires, similar to that already included in a California law requiring replacement tires be as fuel efficient as OE tires. (The law has yet to be implemented.) Meanwhile, SEMA urges consumers to also focus on critical safety issues such as tire inflation and overloading of vehicles.
In a separate but related rule issued several years ago, as of September 2009 tire manufacturers will be required to print the tire's manufacture date in an easy-to-read, four-digit code on the outside of tires. The date is currently printed on one side of the tire but coded in a fashion that it is difficult to decipher by most consumers and frequently facing inside when the tire is mounted. For more information, contact Stuart Gosswein at email@example.com.
On Friday, May 9, 2008, the ABC news show 20/20 ran a special report on the dangers of old tires. The news show used undercover reporters to purchase "new" tires from various retailers and tire stores. Some of these so-called new tires were anywhere from four to 14 years old!
The report said these old tires are "ticking time bombs." As rubber ages, it increases the risk of the tread separating from the tire, causing a sudden blowout and loss of control of the vehicle.
The average consumer assumes that when they buy new tires for their vehicle, they are getting new tires, not old unsold tires that may have been sitting in a warehouse for years. The date code is not obvious, and if you don't know how to read it, it is just a meaningless number on the side of the tire.
The 20/20 report said that because there is no expiration date on tires, it creates a potential hazard for consumers who buy new tires but are actually getting old tires that may be too dangerous to use.
The 20/20 report said some experts are now recommending an expiration date of only 6 years from the date of manufacture, whether a tire has been in use on a vehicle or has been sitting in a warehouse.
In August, the Missouri-Kansas chapter of the Automotive Service Association (ASA) emailed its repair shop members on the potential dangers of old tires. The mailing was titled "Risk Management: Tire Aging."
Here is a summary of what the notice said:
For years, a tire's condition has been determined by the depth of its tread. This may work for tires on vehicles that are properly maintained and driven the typical 12,000-15,000 miles annually, but vehicles that are driven less or sporadically, tire aging can be a real safety hazard.
As a tire ages, the structural integrity deteriorates both on the surface and on the inside of the tire. The deterioration on the inside of the tire can not be seen, and at this time there are no standard tests to determine the true condition of the tire.
Over time the rubber cracks, which eventually can cause the steel belts in the tread to separate from the rest of the tire. Environmental conditions like exposure to sunlight or coastal climates, as well as poor storage and infrequent use accelerate the aging process.
The age of a tire can be determined by its date code. Tires made in the 1990s have three numbers at the end of the DOT code, while tires made after 2000 have four.
According to experts, tires older than six years become increasingly more dangerous regardless of how long they have actually been on the road.
If you need a new set of tires, are used tires safe to use? It depends on the tire, but yes used tires can be a less expensive alternative to buying new tires IF they meet certain criteria. For more information on this subjct, see Used Tires.
What Tire Dealers Should Do
Auto service facilities and tire dealers should employ the following tips to help prevent customers from experiencing tire failure from aged tires:
Store tires in a cool climate away from sunlight.
Determine age of tires.
Implement a "first in-first out" rotation strategy.
Check the age of all tires both serviced and sold.
Check existing tire inventory and new tire shipments. Tires that are past the manufacturer's service life should be returned.
Make sure all technicians are properly educated on tire aging.
Educate your customers on tire aging and the importance of having good tires on your vehicle.
Recommend to customers replacement of aged tires.