What is considered a too old of a tire to be reliable?

I just went to a conference and one of the talks was about tire failure. It was mentioned that tires generally have a shelf life of 10 years. I also learnt how to read the sidewall code that refers to age. Here is a link, http://www.bfgoodrichtires.com/tires-101/tire-basics/about-tires/reading-your-sidewall.page

Basically, you look for the word "DOT" (Dept. of Transportation) and then you have a bunch of letters/numbers. The last four or three (if older than 2000) tell you the week/year when the tire was manufactured such as WWYY (W=week;Y=year). Before 2000 it was only the last digit of the year so you will have to infer the decade.

Looking at the BF Goodrichs in my car, I found the code on the inside wall. Mine were from 2001, which makes sense, because that's when the car was restored. The thread looks like new, which coincides with the paperwork that indicates the car was driven about 5k miles from the time it was restored 12 years ago to when I bought it. My question is, even though the tires look great, should I be concerned about age? Over time they are more likely to delaminate, especially if they have been patched or externally hit something. Right now I don't have new tires in my budget. Maybe in couple years so I can upgrade from 235s to bigger tires.

I don't go by the date code on the tires - I go by the physical characteristics of what I see: cracking from dry-rot, etc.

I say this because I have a set of 33x15.50 Interco Super Swamper TSXs on my Jeep... since 1996. Not a speck of dry-rot (or other signs of aging) to be found anywhere. I hardly ever drive the Jeep, and it lives in the garage for the most part, so I'm sure that's contributed greatly to the longevity of the tires. But until they start showing signs of aging, I'm not looking to replace them any time soon - not at $350 per tire, that's for sure.

a member here told me of buying some older Mickey Thompson's that had been stored indoors and out of sunlight but were 8 or 9 years old. Within a few months of putting them on, he had a belt failure in one of them-and while that tire may not be a fair comparison- old tires can look fine and still fail.

I found several articles addressing tire age. Here is a good one: http://www.edmunds.com/car-care/how-old-and-dangerous-are-your-tires.html

My expertise is in polymers and what happens is that rubber, as many soft (plasticized) polymers such as vinyl, will oxidize due to exposure to oxygen in the atmosphere. Their oxidation will be accelerated due to many other factors such as heat and UV. Therefore, the rubber of a tire that is stored in an indoor environment even when not in use will oxidize and age. This means that it will harden and crack over "time". How fast it happens depend on the type of rubber so it is hard to determine how long the tire would last. I think that's why they use 10 years as a safety limit. It could last longer or less depending on many factors. I also read that for tires used at high speed it should be 6 years. I am sure the latter recommendation is adding a level of safety due to the inherent risk of tire failure at high speed. If the car is driven at "normal" speeds then the risk is obviously less.

I am answering my own question here, but based on what I know and read, the risk of failure increases as the tire ages. The risk of failure accelerates with time, temperature, use, and other factors. How the tire looks on the outside may be a good measure, but it is nearly impossible to know how it looks in the inside. If the rubber hardens and starts cracking on the inside we won't know until it is too late. I will keep mine for a little longer until my budget allows a new set. And... won't be driving at 100 MPH.

Tires are loaded with fillers in addition to rubber. and the belts add a degree of complexity to the innards that is hard to predict how they will react. I would think you would be okay with conservative driving, but if I were in your shoes, I'd be putting aside some money for new ones

Guys - thank you! This is good information, as well as good common sense.

I totally agree on the conservative driving: less speed = less extensive damage, typically.

My Jeep rarely sees the higher side of 45-50 mph - because the tires are so big (and seem to have minds of their own) I avoid highway driving with it... mostly because I resemble a drunk driver just correcting from road surface imperfections. rofl

On vehicles like my wife's car, the Mustang, and my Ram that primarily drive at speed on the local freeway, yeah - I tend to pay more attention to the tell-tales offered-up by the tires.

Good question. The rear tires on my Mustang are 20+ years old and seem OK. I certainly am NOT going to throw away my tires every 4-5 years. As long as they are not visibly dry-rotted and and have decent tread on them, I'm running them.

I do however make efforts to keep the car away from ozone-producing machines (electrical motors and such) in my garage...ozone being the killer of rubber.

I do however make efforts to keep the car away from ozone-producing machines (electrical motors and such) in my garage...ozone being the killer of rubber.

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Ozone is like oxygen in steroids, which will accelerate oxidation tremendously. However, keep in mind that the oxidation process occurs over long periods of time so I don't expect a short ozone exposure to affect the longevity of the tire by that much.

Storing your car in a garage with electric motors near will definitely age your tires and other rubber components quickly.

It is all a matter of degrees-unfortunately since the damage isn't clearly measurable, erring on the side of caution is my preference.

I wouldn't get on a motorcycle with tires over 5 years old

A car isn't quite as bad. That being said I wouldn't drive on 20 year old tires any further than to the tire shop-but that is me, and I wouldn't presume to say how much risk anyone else should be willing to take.

I drive my Mustang HARD at times. I don't carry a spare, cause my tire size is large enough a full size won't go in the trunk-I don't want to see a blow out tear up the quarter panel or a fender and have to then repaint the car to fix it. Tires are relatively cheap when you view them in terms of the damage repair costs that can come from failure.

Assess your risk tolerance and the issue for yourself.

a member here told me of buying some older Mickey Thompson's that had been stored indoors and out of sunlight but were 8 or 9 years old. Within a few months of putting them on, he had a belt failure in one of them-and while that tire may not be a fair comparison- old tires can look fine and still fail.

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yup..they can look good and fail.. mostly cause steel belted tires need to be rotated one way only. if you buy a used set of tires it is hard to determine what side of the car they was on during there life....Reason why you never rotate your tires side to side..Steel belts get use to going one way and get tight inside the tire.flip it around and boom...tire can fly apart and look just fine...but long as you know the history usualy the tread will fall off before a blow out.

My dad once took a gamble on some truck tires for his ford...they looked awesome..Not a splitt or anything mounted on rims still great tread.. his buddy only wanted 20 bucks for all 4...He stuck them on the truck..We drove around town for about a half hour, then the truck started riding funny..We got home and jumped out too look at the tires..and there was football sized eggs growing out of the side of the tires...We had to walk inside and wait while each one exploded while it sat in place...lol

When I got my 73 from the 3rd owner (1998-2012) I contacted the 2nd owner (1987-1998) and showed him pics of the car and how it looked.

The 2nd owner told me that the tires were the same when restored the car in 1990. Scared the bejebbies out of me as they were 23 years old and I did about 500 miles on them.

Obviously I went for new tires.

The tires might look good and have plenty of tread but they are still old. I replaced mine soon after getting my car because they were 11 years old and I had driven my car in excess of 80 MPH once.

I decided that it was not worth body damage from a tire coming apart at that speed. And no, I don't normally drive my car that fast but it was necessary as an evasive move to keep from getting hit on the beltway here in Houston. It was either speed or brakes. I knew the car was better at speeding than braking. I was definately right on that choice. I must say it was amazing how quick I was at that speed from around 45 to 50 MPH! Even had to fight it a little to keep it in a straight line.

Just look at it like insurance when you replace them. If you only drive short distances at very slow speed not that big of risk. However if you drive a long distance even slow, the tires are going to get hot and seems like they are more likely to fail.

Good question. The rear tires on my Mustang are 20+ years old and seem OK. I certainly am NOT going to throw away my tires every 4-5 years. As long as they are not visibly dry-rotted and and have decent tread on them, I'm running them.

I do however make efforts to keep the car away from ozone-producing machines (electrical motors and such) in my garage...ozone being the killer of rubber.

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OK, Kit! Are you nuts? Go buy some new tires and donate those to the tire museum! I should have sold you my 11 year old tires. I did keep one to mount as a spare tire but just never got a rim for it.