How long do tires last (age) and how?

Joined
Nov 24, 2003
Messages
3,122
Location
Middle of Iowa
I have heard anything from a tire is starting to get "old" after anything from 3-6 years. I have a couple questions about how tires age...

#1 - does the mold release compound help slow aging?
I have a older set of tires that came with a motorcycle (my Guzzi). They were about 10 years old (or more), but still brand new in a cardboard box, stored in a climate controlled garage. I went ahead and had them installed on my bike. I have about 2000 miles on those tires, including a trip to The Tail of the Dragon where fun peg scraping times were had. The tires look like brand new, and are performing great! The seem to grip just as well as a brand new tire should.

#2 - is it just the outer layer of rubber that is effected?
I recently purchased a C5 for AutoX duty and weekend cruiser. She has older rubber...guessing at least10+ years old, but was stored again inside in climate controlled environment. There is no cracking, no vibrations, and they seem to ride good (and seem brand new visually). The first couple of times I could tell the rubber was hard...but as I drive it, it seems to be wearing that old layer off, and the grip is improving...a lot. Does rubber age from the outside in? I plan on AutoX'ing this weekend...I know they will be old crappy tires, but could they improve throughout the day? I'm actually ok with bad rubber as I learn the limits of the car, and will get better rubber when I can start being competitive with this car.

#3 - Both of the examples above are currently in my garage, and in use today. Am I sitting on a timebomb?
 
Joined
Aug 5, 2021
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211
Location
Kingman, Arizona
For any motorcycle, you want good tires. A blow out on the freeway could end up being a major disaster, even fatal. On a cage (car), tire life can depend on climate, but is never forever. In Arizona, four years is a good gage for when to replace tires. The dry air is very hard on tires.
 
Joined
Dec 7, 2003
Messages
11,885
Location
Florida, Cape Coral
UV is the main culprit when it comes to tire aging. If in a covered box inside, I see no reason to not use them. The time limit of -7 to 8 years is for tires ON the vehicle and used daily. Ed
 
Joined
Jul 30, 2003
Messages
2,171
Location
GA
Frist, as a tire shop's want of revenue increases, the shelf life of a tire starts to be reduced.

Now, the question is one of chemistry. Are the plasticizers, UV protectants, etc stable in the tires or are they breaking down and/or leeching out over time?
 
Joined
Mar 23, 2003
Messages
1,612
Location
Hopewell, Virginia, USA
A cousin worked for a company that built special bodies for new Class 7 trucks and used those trucks on its specialized heavy jobs. He said these were his company's rules on tires:

All rear (load-bearing) tires replaced after 7 years, no exceptions
Front tires in good condition can go up to 10 years with regular inspections

These were trucks in regular use, not sitting. Also, this part of the country is not hot and dry a lot, unlike the Southwest, which makes a difference.
 
Joined
Jul 18, 2020
Messages
218
I've done hardness testing bike bicycle tires that have been aged 1, 3 and 5 years. Based on that, and based on the cost of medical procedures in the US (even with good insurance), I would toss them...

I know it's not an apples-to-apples comparison, but in terms of compounds the aging process should be similar--and that is, the entire compound is harder than when it was new. You likely got a bump in traction when the mold release agent was fully worn off the tire. Yes, the mold release probably helped slow the aging process, as did not having them mounted. They do age from the outside in, but on both sides of the tire.
If the tires were stored at room temperature, that would help greatly; but 10 years is a long time.
 
Joined
Jan 8, 2018
Messages
212
Location
MI
I got my motorcycle out for the first time in a few years and rode around a bit. Then noticed my tires were from 2006. They still look great, but I just ordered a new pair anyway as I don’t want to risk it. I wasn’t planning on an extra 500 bucks for tires, install etc!
 

FZ1

Joined
Feb 7, 2008
Messages
5,751
Location
Texas
I got my motorcycle out for the first time in a few years and rode around a bit. Then noticed my tires were from 2006. They still look great, but I just ordered a new pair anyway as I don’t want to risk it. I wasn’t planning on an extra 500 bucks for tires, install etc!
Good call. I like the Michelin Pilot Power One tire not too expensive, soft, and handle well.
 
Joined
Feb 6, 2021
Messages
1,014
Location
Massachusetts
I have heard anything from a tire is starting to get "old" after anything from 3-6 years. I have a couple questions about how tires age...

#1 - does the mold release compound help slow aging?
I have a older set of tires that came with a motorcycle (my Guzzi). They were about 10 years old (or more), but still brand new in a cardboard box, stored in a climate controlled garage. I went ahead and had them installed on my bike. I have about 2000 miles on those tires, including a trip to The Tail of the Dragon where fun peg scraping times were had. The tires look like brand new, and are performing great! The seem to grip just as well as a brand new tire should.

#2 - is it just the outer layer of rubber that is effected?
I recently purchased a C5 for AutoX duty and weekend cruiser. She has older rubber...guessing at least10+ years old, but was stored again inside in climate controlled environment. There is no cracking, no vibrations, and they seem to ride good (and seem brand new visually). The first couple of times I could tell the rubber was hard...but as I drive it, it seems to be wearing that old layer off, and the grip is improving...a lot. Does rubber age from the outside in? I plan on AutoX'ing this weekend...I know they will be old crappy tires, but could they improve throughout the day? I'm actually ok with bad rubber as I learn the limits of the car, and will get better rubber when I can start being competitive with this car.

#3 - Both of the examples above are currently in my garage, and in use today. Am I sitting on a timebomb?
To answer number 2 no the entire tire is affected, I've attempted to patch older tires for customers (looked fairly okay on the outside) to discover when I go to sand the inside the brittle rubber just flakes off.
 
Joined
Jul 8, 2021
Messages
227
Location
SoCal
I have heard anything from a tire is starting to get "old" after anything from 3-6 years. I have a couple questions about how tires age...

#1 - does the mold release compound help slow aging?
I have a older set of tires that came with a motorcycle (my Guzzi). They were about 10 years old (or more), but still brand new in a cardboard box, stored in a climate controlled garage. I went ahead and had them installed on my bike. I have about 2000 miles on those tires, including a trip to The Tail of the Dragon where fun peg scraping times were had. The tires look like brand new, and are performing great! The seem to grip just as well as a brand new tire should.

#2 - is it just the outer layer of rubber that is effected?
I recently purchased a C5 for AutoX duty and weekend cruiser. She has older rubber...guessing at least10+ years old, but was stored again inside in climate controlled environment. There is no cracking, no vibrations, and they seem to ride good (and seem brand new visually). The first couple of times I could tell the rubber was hard...but as I drive it, it seems to be wearing that old layer off, and the grip is improving...a lot. Does rubber age from the outside in? I plan on AutoX'ing this weekend...I know they will be old crappy tires, but could they improve throughout the day? I'm actually ok with bad rubber as I learn the limits of the car, and will get better rubber when I can start being competitive with this car.

#3 - Both of the examples above are currently in my garage, and in use today. Am I sitting on a timebomb?
Rubber still hardens even without being exposed to the elements. Putting on 10+ year old tires on a motorcycle is a deathwish
 
Joined
Aug 8, 2008
Messages
6,847
Location
Cali
Still have my original spare tire on my 83 Silverado, no way I would use it, all kinds of cracks around the tire, doesn't look bad from a distance. :)
 

Nick1994

$100 site donor 2022
Joined
Feb 19, 2013
Messages
15,086
Location
Phoenix, AZ
They say 6 years here in the desert and closer to 10 up North.

My '96 Cherokee has a 3 year old set of BFG All Terrain KO2's that look almost new, maybe 5k miles on them. They'll be replaced in 3 years probably looking almost as new. I won't risk it. I even replaced the spare when it hit 10 years old. I think I have 5 years left on that brand new spare. It'll be replaced too at 10 whether it ever touches the pavement or not.
 
Joined
Jun 15, 2003
Messages
38,110
Location
ME
Part of the tire rubber formula includes preservatives. This is why we see some brands to better than others in the same outdoor environment.

I would venture... postulate... that a motorcycle tire manufacturer puts more "good" ingredients in their tires than walmart puts in the Douglas tires for a Toyota. Because they don't want a failure, either.

Keep an eye on things and know what the limits of friction feel like.
 
Joined
Feb 22, 2003
Messages
4,229
Location
Somewhere in the US
I am not a rubber chemist, but I've worked alongside some very talented ones. Here's what I've picked up.

Tire aging is all about oxygen attacking the long chain hydrocarbons and the crosslinking between those molecules. It is temperature dependent, meaning that tires in - say - Phoenix, age much faster than tires in - say - Minneapolis.

It doesn't seem to have anything to do with Ultraviolet radiation from the sun.

That's why tire testing sometimes involves oven aging, or oxygen inflation, but never UV lights.

Since oxygen can permeate through the rubber- albeit slowly - it is not just a surface phenomenon. In fact, the importance of tire aging is about the material just under the top steel belt at the belt end - where the most stress in a tire occurs. That is where failures usually start. We use the exterior as a guide because that is the only indication of the state of things going on inside - at least until you get a failure, which starts as a bulge - and then the separation proceeds very quickly to a tread detachment - very dangerous!

So, No! Mold release compounds don't help protect the tire, but the waxes and AO's (antioxidants) mixed into the rubber do. You can see the waxes as a whitish film that flakes off especially on new tires and the AO's are frequently Rust colored (because they are some form of iron oxide.) Anything that removes those shortens the tire's life - and many tire dressings fall into that category.

AO's get used up fairly quickly, so doubling the amount doesn't double the time the AO's are protecting the rubber. So that is something tire manufacturers can only slow down, but can't fix.

And since the cracking occurs on the surface first, it is used as an indicator, with the idea that some cracking is expected and OK, and it's a matter of degree. So, Yes! you are sitting on a timebomb, but the fuse is very long - years, not days! Plenty of time of take appropriate action.
 
Joined
Mar 3, 2022
Messages
527
Location
Amherst, MA, usa
the tractor hasa 70/80 y/o set of tires. Back then almost all ruber coumpound. No checking (tread it there as we use it in the forest & crop fields). The trucks, cars'n bikes, etc we look at condition. When looking bad we change out (tread, checks, bubles, rash, etc). Life span is varable 3 - 5 yrs as we go thru them.
 
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