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Author Topic: Extreme Performance Summer tires in cold weather  (Read 6380 times)
travisb
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« on: March 28, 2015, 02:44:33 PM »

I recently purchased new Dunlop Direzza ZII Star Specs and new wheels for my Subaru BRZ. Dunlop and Tirerack say " it is not intended to be serviced, stored nor driven in near- and below-freezing temperatures, through snow or on ice." I've read stories of Summer tires cracking when driven in cold weather.

Tomorrow morning it is supposed to be in the low 20's and 37-43 around noon. Would driving to the track and running these tires tomorrow damage them and should I switch back to my stock tires and wheels instead?
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Shane Irving
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« Reply #1 on: March 28, 2015, 03:48:03 PM »

Im going to run hankook rs3 this season and was thinking the same thing but I got my answer when I was loading up the wheels into the trunk tonight. Found a small nail in one so I wont be running them till i get a patch on it. Just my factory pirelli p zeros instead, but I think once heat can get built up in the tires should be ok. The first run or 2 will be like driving on ice.
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gunny
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« Reply #2 on: March 28, 2015, 03:58:59 PM »

put a plug in it until you get it patched!

Travis, the tires will be fine. a little slippery in the morning but they wont crack or get ruined.
I drove mine today, it was cold.

Gunny
« Last Edit: March 28, 2015, 04:00:38 PM by gunny » Logged
travisb
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« Reply #3 on: March 28, 2015, 04:00:53 PM »

edited, just saw gunny's reply to me
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ccann26
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« Reply #4 on: March 29, 2015, 03:25:50 PM »


 I believe that warning is intended for "normals" not autocrossers....
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If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. Mark Donohue
travisb
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« Reply #5 on: March 29, 2015, 06:04:07 PM »

This is what I was afraid of happening - http://www.autoevolution.com/news/c7-corvette-cracked-tires-problem-explained-by-michelin-engineer-93114.html

Luckily, it looks like my tires survived the day.
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Marc
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« Reply #6 on: March 30, 2015, 03:38:16 AM »

There is a certain temperature, different for each polymer, called the glass transition temperature, or Tg for short. When a polymer is cooled below this temperature it behaves in an increasingly brittle manner.

So, if the soft compound tires we run are cooled enough they can become hard and brittle and can crack when subjected to load. This is the reason for the C7 tires cracking... and why Tirerack won't even ship R-comps during the winter months.  I was recently told by a BFG/Michelin tire engineer that for their current crop of "ultra high performance" tires, Tg starts around 40 F but in moderate weather, as long as you warm the tire up by driving on it, they should be fine.
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travisb
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« Reply #7 on: March 30, 2015, 04:40:53 AM »

Marc, thank you for the explanation. I have a basic understanding of the tires becoming more brittle in the cold. I like exact figures and I wish tire manufacturers could state more specific temp/weight/pressure scenarios of when the tires reach Tg.

I understand they need to be vague in their wording to protect themselves from liability. They can't really give an exact figure because even tires of the same compound can vary so the lawyers just say "they should not be used near X temperature."

This is my first experience with new tires in this level and I just wanted to make sure they would be ok.

Thanks again.
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Stu
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« Reply #8 on: March 30, 2015, 04:41:38 AM »

I daily drive on my RS3's and Rivals all year.  Snow, ice, rain, below freezing etc.  Just make sure you don't let anyone borrow your car in those conditions.  
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whiteryder
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« Reply #9 on: March 30, 2015, 09:07:13 AM »


I think Marc is just making excuses why he was too chicken to come out and
race a poor lowly base Carrera yesterday.
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Marc
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« Reply #10 on: March 30, 2015, 11:02:19 AM »


I think Marc is just making excuses why he was too chicken to come out and
race a poor lowly base Carrera yesterday.


So, you did miss me yesterday!

Actually, as afraid as I am of getting beaten by a girl in a lowly base Carrera... I was home sick.
But I WILL be at VMP on the 19th!
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sjfehr
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« Reply #11 on: May 31, 2015, 03:51:04 PM »

The risk of tire damage in cold weather is specific to each tire.  I daily drove ZI* and ZII all winter long for 6 years, including temps down into the teens with no issues whatsoever.  I was surprised how much grip they had, even in extremely cold temperatures- not exactly competition level, but better than a typical snow tire, and grip came up once they got some heat.  They were usually warm to the touch by the time I got to work.

I tried driving once on snow... never again.  Cold is one thing, but these are NOT snow tires.

What'd you think of ZII* in the cold, any issues?  I haven't had mine out much below freezing.
« Last Edit: May 31, 2015, 03:52:59 PM by sjfehr » Logged
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