At what temperature Summer tires unsafe to use

[CapriRacer]

Originally Posted By: 69GTX
If there's a risk of summer tires turning brittle in winter, then even being parked in one's garage could be enough stress to crack them, especially if subjected to ambient temps of -20F to +20F in unheated garages. I've never heard anyone complaining about it so it's probably not the case. ....


Just an FYI, the phenomenon is rare, but it does exist. I don't know how other tire manufacturers handle this, but the one I worked for changed the formulation when it was discovered.

 

[d00df00d]

Originally Posted By: 69GTX
1. Dude....read what I wrote.

You said "I've never heard anyone complaining about it so it's probably not the case." I know what you're saying, but that sentence as-is is a textbook example of a logical fallacy.


Originally Posted By: 69GTX
It concerned selective winter driving....not a DD in daily slush. The OP is not suggesting driving in slush either or even if ambient temps are under 32 deg F. That's no Daily Driver. They should be as selective as needed based on the weather.

All OP said on this point was "I was going to drive the car all winter until it got real messy (snow) this winter." That's not the same thing as "only when it's nice."

If the plan is to drive through the winter until the weather report gets too rough, there WILL be days when there's unexpected moisture on the road. Maybe even ice. Could be from snow that comes unexpectedly in the middle of the day, could be something left over that didn't thaw or run off completely. If you encounter that while you're on max-performance summer tires, you're screwed -- and someone else might be, too.


Originally Posted By: 69GTX
2. No one in this thread has complained about owning a summer toy that sits for most of the winter except for brief maintenance runs....and worrying about "cracking" tires. In fact, I'm the only one that replied in that manner.

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Originally Posted By: 69GTX
3. I own a '99 SS which you could have easily seen in my sig line. 350 hp 6 speed with a fairly stout 1st and 2nd gear. It can easily break loose under spirited driving on dry roads. It's no daily driver nor a Prius.

Nor is it rear-heavy with a back end that can swing like a pendulum when it breaks loose. And it has a massive understeer bias at the limit. The Porsche is much more capable and more controllable on the limit IF you know what you're doing, but also quicker to react and more neutral at the limit.

Again: different car, different tires, different usage. Different ballgame.


Originally Posted By: 69GTX
If the winter is bad this year both the OP's car and mine will be sitting for most of Dec-March. We've been lucky with 3 out of 5 recent mild winters.

Exactly. Lucky. As in, if OP intends to drive the car more often than not, he's rolling the dice.

That's why so many in this thread have recommended winter tires. That would take all of the guesswork (and irresponsibility) out of the equation. There would be no need to wring hands about weather reports, and no need to worry about what was going to happen to the tire compound.

 

[69GTX]

Originally Posted By: d00df00d
All OP said on this point was "I was going to drive the car all winter until it got real messy (snow) this winter." That's not the same thing as "only when it's nice."


Along the Connecticut coast at 42 deg F this morning it's snowing out. The OP's initial conditions (until snow) have been met here in the lower northeast. La Nina is in town.

 

[02SE]

Originally Posted By: 69GTX
If there's a risk of summer tires turning brittle in winter, then even being parked in one's garage could be enough stress to crack them, especially if subjected to ambient temps of -20F to +20F in unheated garages. I've never heard anyone complaining about it so it's probably not the case.



Actually, that's exactly what I was talking about in my previous post. Just pulling the cars and bikes out of the garage into the driveway, in subfreezing ambient temps, flexed the casing(s) enough to develop cracks in several of the summer performance compound tires.

I had a long-winded post typed out about talking with tire engineers for both the car and bike tires, but when I hit 'submit' earlier, I got a screen stating the board was being upgraded, and my post was lost. I'm not typing all that again.

 

[raaizin]

As the Original poster I thought I would give an update. My intent was to use the car only when it was nice out. Above 32 degrees and dry. As for some post about ice and snow, not sure where I inferred that. Thanks for all the responses it has been entertaining. I was able to locate a 2nd set of winter tire/wheels. I figured why take the chance and I like these wheels so I have a second set if I choose to switch wheels. Here are the wheels I purchased, these should handle any weather I should encounter:

http://rennlist.com/forums/parts-marketp...zero-tires.html

 

[IndyIan]

Originally Posted By: CapriRacer
Originally Posted By: 69GTX
If there's a risk of summer tires turning brittle in winter, then even being parked in one's garage could be enough stress to crack them, especially if subjected to ambient temps of -20F to +20F in unheated garages. I've never heard anyone complaining about it so it's probably not the case. ....


Just an FYI, the phenomenon is rare, but it does exist. I don't know how other tire manufacturers handle this, but the one I worked for changed the formulation when it was discovered.


I emailed bfg/michelin about my sport comp 2 summer tires and their cut off was -7C. Any colder and the tires shouldn't be used or mounted, etc. until they have been warmed up as they will crack. This fall I ran them in 0C before taking them off and they were a bit lumpy for the first mile in those temps.
I also recall a buddy at autocross having some DOT R-comps that he just stored in a shed so they got down to -25 -30C and they still cracked in the spring when he ran them even though it was 20C out as the cold changed the rubber somehow.

 

[d00df00d]

Originally Posted By: raaizin
I was able to locate a 2nd set of winter tire/wheels. I figured why take the chance and I like these wheels so I have a second set if I choose to switch wheels. Here are the wheels I purchased, these should handle any weather I should encounter:

http://rennlist.com/forums/parts-marketp...zero-tires.html

That oughtta work for sure. :]

Enjoy!

 

[ecotourist]

Originally Posted By: 69GTX
...ice can show up unexpectedly. Though in 45 years of daily driving in northeast winters, I don't ever recall sliding or losing traction under commuting conditions unless the road was already wet/snowy. Never on a dry surface.

I've seen it a couple of times in western winters.

First time I was driving on a bare highway in mid afternoon on a nice day in winter on the prairies. Somewhere around freezing. No recent snow or rain. I suddenly noticed a half ton truck about 1/4 mile behind me start to weave. Looking in the rear view mirror the road behind looked a little shiny and when I checked it was certainly slippery - time to slow down. The road ahead looked fine, even though it wasn't. I suspect the road had gotten "frosty" making it slippery.

The second time was on a curve in the mountains. A half ton truck had spun out a few moments before and was in the ditch. That curve was permanently in the shade and I suspect that highway too had gotten frosty.

I'm quite grateful that in both cases good weight distribution and 4 wheel snow tires saved my bacon.

 

[leeharvey418]

Originally Posted By: CapriRacer
I am not a rubber chemist, but my understanding is that some types of rubber are brittle at low temperatures. There is something called the *glass transition temperature* where some materials change properties and some rubbers have this transformation at temperatures we experience in populated areas.


Yeah, I'm quite familiar with glass transition temperature. I should have been a little more specific in my original question - I was thinking about storing summer tires in a non-climate-controlled garage during winter. I've heard that this can cause issues, but I've always questioned whether it was really a 'summer tire' issue, or if people were seeing cracking in competition tires or something and applying blanket generalizations to all summer tires.

 

[Rand]

The "glass translation temp" cracking is mostly with special track tires. Even most summer tires are ok from that.. at regular winter temps... talking -10f or higher..
now if you live in Minnesota or parts of Canada it can affect many more tires.

Summary
Storing your autocross tires in the unheated garage at -20f could easily lead to tire failure.. depending on the tire.

There are some really great UHP all seasons such as the Pilot Sport AS/3. They will have levels of grip similar to most uhp summer tires while allowing you to drive at 20F out... will they do good in the snow... not really.

 

[leeharvey418]

Right, and even if a tire's rubber compound did cross the glass transition threshold, there would still need to be some strain applied (like from the underlying steel structure not contracting as much) to cause tread cracking.

 

[slacktide_bitog]

Originally Posted By: raaizin
As the Original poster I thought I would give an update. My intent was to use the car only when it was nice out. Above 32 degrees and dry. As for some post about ice and snow, not sure where I inferred that. Thanks for all the responses it has been entertaining. I was able to locate a 2nd set of winter tire/wheels. I figured why take the chance and I like these wheels so I have a second set if I choose to switch wheels. Here are the wheels I purchased, these should handle any weather I should encounter:

http://rennlist.com/forums/parts-marketp...zero-tires.html


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