Aging tires



Hi, yesterday on the TODAY show (NBC) they did a segment about aging tires-- tires that are more than 6 years old, regardless of use (even zero miles) apparently are more prone to selfdestruct when used than younger tires. They gave a tragic example of a woman in Fla who had a flat, put on the never before used spare, which was the same age as the car (10 yrs), then let her son drive the car. At highway speed, the tire blew, he rolled multiple times and died. The correspondent then said that DOT mandates a manufacturing code be stamped on the tire, and showed a graphic so you could see where to look. As it happens I had just purchased a new set of tires the day before. I ran out and checked my tires, and one had a date in '07, reasonable I thought. The other three were just blank in the date spot! Should I be worried? Could I have counterfeit tires? Is Goodyear violating the law by not date stamping the tires? Should I go back to the shop and demand properly dated tires??


The date stamp is there somwhere, but don’t get worried about this. Unless you bought the tires at a yardsale they’ll be fine. They don’t sit in storage or the store that long. Manufacturing and shipping quotas are based on market demand, and it’s pretty scientific and accurate.

Realize that these TV shows are sensationalistic to the extreme. And the 6 year age limit is set by the buys whose business is selling tires. A 10 year old tire stored out of the sun should be fine. There are millions and millions and millions of people driving on full service spares without incident. One tire that blew for unknown reasons is statistically no where near an indication of a widespread problem…except to sensationalistic TV shows. Actually, internal defects in new tires aren’t as uncommon as they should be, they can cause heat buildup and catastrophic failure, and they’re totally unrelated to the age of the tire. And that spare was probably low in air pressure of it hadn’t been checked since it was new.

NBC found a tragedy and created a “chicken little” sensationalistic show about it. Don’t lose sleep over this. Monitor your air pressure and tire condition regularly, as you should do anyway, and don’t worry about this.

By the way, if NBC wanted to do something real on this subject they’d do a show on how much of a safety compromise “doughnut” spare tires really are, especially in bad weather and on pickup trucks. Or on why the DOT never required the anti-wash brushes over the rear wheels of trucks, which tests have proven makes a huge difference in preventing the wash from wet roads from obliterating the vision of the cars next to and behind them. But those subjects would take actual work to put a show together on. And they would not be as dramatic. It’s easier to take one tragic incident and blow it completely out of proportion.


If you have been following the show, Tom and Ray do talk about tires aging. Dry-rot and dry, cracking rubber does happen to tires over time. The case you are talking about just shows the danger of using a spare full time rather than replacing/repairing the flat tire. A spare is just that, a spare. It’s job is to get you to a shop to get you tire fixed. The trunk where the spare is stored is not always water tight…spares will age over time. As for your date stamp…the real test is visual inspection. You should inspect your tires for cracking, un-even wear, etc and for proper inflation. You should also inspect your spare and check it’s inflation regularly, even a doughnut. I would venture a guess and say, in the blowout case, the spare had never been inspected or checked for proper inflation. If the tire was low, then it was an accident waiting to happen.


The tire industry is in a state of transition from putting the date coding anywhere - and usually it was the side that was convenient to change in the manufacturing plant, but that was generally the side that went inboard on the vehicle - to the side intended out per the new regulation. That has to be 100% complete by 2009.

And, yes, rubber deteriorates with age even if not used. It gets attacked by oxygen and gradually loses its ability to flex. If the tire is exersized, this will come out as cracks, but that only is visible on the surface. Inside the tire - where it really matters - the rubber will tear and separate - and you won’t be able to see the bulge that gets created until shortly before it comes apart.


i think the story was way over sensationalized. Don’t worry about the tires, they are fine. If you went to a reputable shop or chain shop, these guys would not risk their business with a tire they would not stand behind. They move way too much stock to deal with that kind of crap.

I venture to guess that the spare in the story was a doughnut, since 95% of the passenger cars made in the last 15 years are equipped with them. The accident happened at highway speed. In Florida, highway speed can mean 70 MPH and over easily, even in the 55 MPH speed zone. This doughnut was rated for 50 MPH max. I wonder if excessive speed had anything to do with it? Especially if the tire was not inflated to 60 PSI, like the doughnuts are designed for. It was 10-years old, and when was the last time your pressure checked your spare? This is the exact conditions the Mythbusters episode showed would blow even a good tire apart.

BTW, it has been a known fact in the industry that these are the conditions a tire will blow out in. I’ve seen numerous warnings about it, but am still amazed at the number of people I run into that have no idea how to check the pressure in their tires (or at least claim not to know).

FWIW, whenever I get a new or new-to-me car, I always go to my local salvage yard for a full-sized rim. I travel a lot, and I once got stuck at a late night stop with a flat tire, and only the doughnut for a spare. No shops open on the weekends, and I had 200 miles more to go. At 50 mph, it was hell, but the doughnut held up. I was at the junkyard the next day getting a full-sized spare rim, then tire shop for two new tires, and the survivor on the spare rim. Never want to face that same scenario ever again.


The summer heat in FL will deteriorate tires more quickly than in the northern US. I, for example, ran tires on our motorhome to 12 years of age with no problem and even now have a 96 car with three of the four original tires, one being lost to a puncture too close to the sidewall. I must admit that the car has been parked in the summertime and used in the winter but my point should be clear. High temperatures and strong sunlight deteriorate tires so the 6 year limit covers all but may not apply to your particular conditions.


Here is another news story about possible problems with cars that I will not worry about:


I have a set of tires on my '76 El Camino that are 10 years old and still look pretty good with no cracking. This is on a car that sits outside in the sun in Texas. I wouldn’t worry too much about yours.


“…I have a set of tires on my '76 El Camino that are 10 years old and still look pretty good with no cracking. This is on a car that sits outside in the sun in Texas. I wouldn’t worry too much about yours…”

10 years in Texas?

Borrowed time, my friend!!


I agree. You might be fine in the northern tier of US states or further north in Canada, but parked outside in Texas, no.


I’ll post on this board when one of them fails if I survive. I drive this thing about 2K miles per year and never exceed 55 mph. I doubt if I’ll ever pony up the $400 for a new set.


Great answer mountainbike.


Look at it this way. Let’s say your tires carry a 50,000 mile warranty. The average American drives about 12,000 miles a year. That means your tires should last at least four or five years. The average Joe can ensure they last this long by applying tire dressing once in a while or parking in a garage, or putting a cover on the car. Keeping your car in a garage will protect the tires from sun and weather exposure.

So the risk of aging tires only becomes an issue if you don’t drive many miles. These folks might consider replacing their tires after six years.

By the way, don’t try tire dressing on motorcycle tires. It would ruin them. Besides, many motorcycle tires last less than 10,000 miles.

Take a look at where your spare tire is stored. If you have it underneath your car, like most pick-up trucks and minivans, your spare tire is being exposed to the elements. If it is stored in your trunk, it is not being exposed to weather and reflected sunlight. It is, however, being exposed to extreme temperatures. Even if you have a full van or small SUV and your spare is stored on the back of your vehicle under a cover, it is being exposed to the elements and should be replaced as often as necessary.

When was the last time you checked the pressure in your spare? I am willing to bet the woman’s spare tire was under-inflated. That will make the tire overheat. I am also willing to bet her spare tire was stored in a place where it was exposed to the elements. These are both important considerations.


You’ve covered one of the primary culprits in rubber deterioration- UV light. However, oxygen and the more radical form of it- ozone are just as damaging if not more so. The atmosphere in your trunk is not immune to the presence of these and the rubber will still deteriorate due to them.




I just recently saw the special. I have to admit that I was surprized at the age of some of the “new” tires they found as well as at some of the sorry explanations thay got when they asked about them. Simple honesty, simply explaining that that scenerio is normal for the industry, is the best answer. I agree with the show that “coding” things like dates such that nobody can readily understand them is a pathetic joke. It’s done in the food industry also.

However, I’s have to know an awful lot more before blaming that for the referenced tragedy. there are so many other far, far more likely causes than that. My guess is that the old tire as a cause theory was created for the lawsuit rather than as a result of an unbiased scientific study. I’ve been driving for over 40 years, almost certainly using old tires and old spares, and I’ve never had a tire blow out without a clearly identifiable externmal cause (nails and screws coming out and in one case a ripped sidewall…darn granite curbs).

It’s also very common for people to put on old spares without checking the air pressure, and IMHO that single cause alone probably is the source of the high majority of blowouts.


There should be a lot less ozone in a trunk compared to outdoors.