so went to get a 'free' change over from my local chain store. they said my snows .. semparit ice grip 2's.. were too 'old' being from 2005. plenty of tread left, and the best snows i have ever run on any vehicle. so got them installed at my local trusted indy with no problem. they said great tires. no dry rot at all.. good tread..question is what is too old? or is it mainly the condition of the tire?
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'91 244 200k auto

My opinion is far form expert, but here goes: Tires that are 4 years old are getting too old. At that point I think the rubber tends to slide instead of gripping on a hard stop. Even with full tread. My.02, worth what it cost.

When your trusted local indy told you that the tires looked OK - that is a good sign - they look at a lot of tires.

You should closely inspect the tires after a few weeks - signs of age might show up after a number of miles.

I would also check pressure weekly for a few weeks, especially as the temperature gets colder and lowers pressure.

When traffic allows, I would also try a few panic stops under different conditions to see if I think that the tires are performing properly.

Rubber will degrade over time, and the speed depends on how the tires are stored. If they are kept in a dark, cold and ventilated area they will keep much longer than if they are stored in a steel container outdoor. This makes it difficult to say on a general basis when a (winter) tire is too old. What I do, is to drag my thumb over the sipings and compare with a new(ish) tyre. If mine feel significantly harder, I get new ones even if the tread is okay and I don’t see any cracks. Typically, I’ll replace them after ten years, and I store mine in the basement.

Erling.
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"got them installed at my local trusted indy with no problem. they said great tires. no dry rot at all.. good tread..question is what is too old? or is it mainly the condition of the tire?"

Yes, it is the condition of the tire that matters. If the rubber is degrading. eg. cracks, then they should be changed.

I run on steel rims so am not worried about getting a flat as I carry a spare and can change a tire. You can get a flat even with a new tire. Of course companies want you to move to their newe$t offering. Do you have the newe$t Volvo, are are willing to risk driving an old car?
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1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

Just attended a tire tech session hosted by Michelin at the Euro Fest car show in Greenville, SC. They talked at length about tire life. Their recommendation was this -- if the tire shows signs of degradation/"dry rot" (tiny cracks in sidewall) then regardless of tread life, no more than 6 years. If the tire doesn't show any cracking, no more than 10 years. Seems that the composite materials tires are comprised are subject to 'aging out'. Here's an article about it -- http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=138 . Likely, the folks at The Tirerack have also been talking to the folks at Michelin.

Did those Michelin folk address hardening of the materials with age?

Recently, while I was out of town, the Boss Lady complained of nearly sliding into someone stopped for a light, with her 89 sedan equipped with Yoko Avid Touring. This was her second notice to me, so I knew the tires had "nice" tread and date code 3309 with none of the obvious checking and cracking I've seen in sidewalls. And I had done some lockup stops on our wet street to test.

She didn't like my suggestion to be careful of oil floated by recent rain and had the tires dispatched the next day and of course loves the replacement set she bought. And on return to town, it was time for me to put the snows on.

Anyway, new tires always feel so much stickier, regardless of tread depth, and I thought 7 years was not too old, but the customer is always right. And those old tires are gone, so I can't even consider doing my fingernail durometer comparison.

Funny, though, when I asked her on the phone what brand she was sold, she said "Michelin" and I was happy with the $440 bill, but when I got home to find they were BF Goodrich, for some reason I wasn't quite as happy. I understand there's no basis for this, but our long-trusted tire guy left to take a job with Honda. :(
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Art Benstein near Baltimore

I had some words with my wife, and she had some paragraphs with me. -Sigmund Freud

They didn't address 'hardening' per se Art -- just 'degradation' in general.

well thanks all for the comments. i did make sure to look very carefully at the sidewalls and there was no sign of dry rot. i was quite surprised really. the tread did feel very soft and pliable. snow tires are usually soft compounds anyway, no?. these tires are stored in a cool dry cellar all summer. i'll keep an eye on them for pressure etc., but so far (a few hundred miles) they look good.

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'91 244 200k auto