Summer tires in colder weather...

The tire manufacturer states that the summer High performance tires should not be used as temps approach the freezing mark. I don't doubt that but I'm curious about why. What happens other than the compound gets hard and much less grippy. Is there an actual failure issue at lower temps? Bill

The reason you stated is pretty much it, rubber compound hardens up and looses its ability to flex and conform to the microscopic pattern of the road and looses the adhesion as compared to warmer ambient temperature. Then there is also the element of snow and ice where proper winter tires will perform much better. I once heard a phrase I agree with 100%: "In winter driving conditions, the worest winter tires will be better than the best summer tires."

They get hard, like a hockey puck. Even on dry pavement, traction suffers. It's particularly bad when it's cold and wet. Obviously it's really bad in any kind of snow or ice. I got caught in a fall snow storm once with Pirelli P-Zeros on my car. It was not pretty.

When I first got the car I had Toyo R1 summer tires on and tried to drive it home on an early winter storm. I couldn't leave the office garage and I ended up taking a cab home.

Summer tires are extremely dangerous in any kind of snow, slush or winter precipitation. In the dry, a lot depends on the tires and their compound. Summer tires that like a lot of heat for max grip (Kumho XS, Hankook RS3, etc.) are often dangerous when the thermometer approaches freezing. Other summer tires like Toyo R1R and Dunlop Star Spec will provide less grip at near freezing temps, but I'd be willing to bet would still hold up favorably on a skidpad vs 5-year old 60k mile all-seasons at temps into the teens. Some tires, like the Yokohama AD08, actually carry a warning not to use it below a certain temp, or it can damage the tire. If you do drive in the winter, be aware of this, and alter your driving habits to match your car's decreased performance. FWIW, I drive on Dunlop Star Specs all year round, and I have never had an issue; I garage my car overnight, though, and it's usually above freezing by my afternoon commute, so the rubber is rarely below freezing for me. On the rare day it snows here, I either take another car or stay home.

Due to a mechanical issue with my sons car I had to loan him my Jeep and drive my P-car today. It has Sumi z3's on it and they are not recommended for cold weather driving. I really have no intention of ever driving it in snow although the c4 aspect of the car should help... I was mainly curious about the integrity of the tire in the colder weather. It's 38 right now but by the time I drive home it should be near or below freezing. It sure felt good to drive that car again...grins

I think you'll be fine. Just be careful!

Your tires won't fall apart, but the C4 aspect won't help you to slow down or turn corners if the tires don't stick well to the road surface, I had Yoko A008R street legal competition tires many years ago that I drove the whole summer while doing auto-X events, I waited a bit too late one year and nearly understeered into some concrete divider while braking for a normal right hand corner when the temperature dropped suddenly that day.

I drove several hundred miles a few winters ago with summer rated tires, but not in the snow, only on dry roads. I had no issues, but I wasn't ***** to the walls either.

All of the above comments are true, but on dry roads you're usually fine if you take it easy until the tires warm up and soften enough to get some grip. I've not yet switched over to my winter tires. We're getting the odd week of overnight temperatures around freezing, but the daytime temperatures are still pretty good. I'll be pissed if I don't get to mount my new tires this year because of a mild winter.

From the Pirelli website: "At lower temperatures, when driving on summer tyres, little elves will appear in the corner of your rear-view mirrors and slowly rock your car back and forth, causing an odd vibratory motion that, at high speeds, are best avoided." Ok, maybe they didn't say that, but I have a hard time believing that it's a ploy to switch tires. Given the speeds we drive at, why risk it?

The other side is brakes. Depending on the pad compound you are using it will could be difficult to get heat in the pads so it could be difficult to stop especially when you are starting out.

the glass transition temperature of summer tires is high 30's...hockey puck! Just move to FL it's still 75 degrees here (:

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Wow. Now that's the first time I've heard anyone on RL say glass transition temperature, never mind know what it means.

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What kind of winters do you see down in Chesapeake? With the weather getting colder in Washington D.C. area, I've noticed my Star Specs are losing grip as they are having trouble warming up like they do most year round. I also am due to rotate, too... I'm at a standstill with deciding to put back on the Michelin Pilot HX MXM4 down to 5/32" or keeping my Star Specs (which the front's are definitively at 5/32" and a bit more on the rear). Even in rain, the Star Specs provide way better grip than the all seasons did. They are just too hard to give up.

Anyone espousing the idea that it's OK to use summer tires in the winter for reasons like "but it's not snowing", "I'm going to take it real easy", or "I'm not going far" really owes it to themselves to try a few full-on panic stops with that tire/temp combination. See, it's not that summer tires won't roll right down the street "just fine" when the temps get cold, it's that when you get into a situation where you really need the proper grip from the proper tires, it won't be available. Some of you are using the same logic that says that since there's a very rare chance that you'll get into an accident, there's no reason to use an infant seat for your new baby. After all 999 times out of 1000 everything will be just fine, right?

In my previous 996 cab I had a good lesson when I aggressively turned to enter a freeway on ramp. The car only turned a few degrees then pushed straight ahead right off the roadway into the dirt and weeds. Luckily there was no curb and no damage at all just a good lesson that summer tires don't stick on cold dry roads. It was about 29 degrees outside. This near local guy had it worse as he wrecked his Lambo the same day he won it. I'm certain his summer tires are mostly to blame and I'm sure he wasn't aware that his car would slide out easily on cold roads. http://www.ksl.com/?nid=148&sid=1858...ter-winning-it

Quotes source post: 9119802

You are correct, but also need to take into account the individual situation. An Iowa winter is very different from a North Carolina winter, and different from... you get the idea. It's currently 67F outside my window right now. When the temperature drops down to 38 for a few hours, then warms back up again it's really not worthwhile to put on winter tires - in those conditions you do as I said and take it easy until the tires warm up and gain full traction.

You definitely have to take your local conditions into account. I've always run dedicated winter wheels and tires on the C4S, but I used to run all-seasons (a.k.a. no-seasons) on our Cayenne when we lived in Indiana. It got cold there and snowed quite a bit, but the roads were flat and straight. Now that we live in the mountains, a true winter tire is an absolute must. I put my winters on the cars on October 15th and keep them on until May 15th. The main question up here is whether you should run studded winter tires or regular winter tires...

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Reading some of posts here. I'm willing to bet the geek factor is pretty high on this board, and many of us can speak somewhat intelligently about Tg and other material properties. (guilty of geekiness )

I could see the PZero Rosso logo on the Lambo video. Definetly not a winter tire!!

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I've been here a long time and would say that there are very few material scientists here. Aside from myself, I would put you as number 3 or 4 that would understand that stuff. What's your specialty?

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Exactly, it all depends on conditions. I have a set of winter tires ready to be installed on my M3, but the conditions have not yet called for it. The 996 I just drive on dry days during the winter.

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Our winters are similar to yours, but with way less snow. The snow removal plan for Virginia Beach is, seriously, "wait until it melts." It's surprisingly effective. As Star Specs on a cold day here seem to grip better than all-seasons .period., there's little point in changing them. For you, though, you may have enough snow days that you need to swap them out. This may be true of certain r-comps, but definitely not most summer street tires. Yokohama AD08 carry a warning and say they're not to be used or stored below -10C/14F. Most others don't bother with warnings at all; I think it's safe to say Tg is at least below -10C for AD08, and very likely far lower than that for most other summer tires. (And yeah, I'm an engineer, too; I have a sneaking suspicion this board is full of us!)

Quotes source post: 9121760

The focus on Tg is a red herring for warm tires, as the only (relatively) "hard" parts of the tires are the apex or the nylon or kevlar belt that runs through the belt (shown in the attached graphic in red and orange - supplied courtesy of Vredestein when I worked with them in a past life). The Tg for all tires is well below freezing. At no point will the tires become glassy (unless you live in ND or MN and are reaching temperatures around -40C) - that would be bad, but parts of it would become more rigid and change the operating dynamics. But, as I said, this is mostly a moot point when the tires are warmed up, as they'll be up in the 150 to 200F range (depending on tire design, speed driven, ambient temp, etc.). Having said that, all tires are designed to operate an an optimal temperature that is different for summer and winter tires - that is a critical difference that affects performance and traction. You will note that the tread design on summer tires is different from those of A/S and winter tires, that makes a big different to cold weather grip - now that is your main issue. Hit an icy patch with cold tires and you're in a ditch. Go out in snow and cold rain and you have nothing to give you traction. I'm not an engineer - I'm a polymer scientist, so actually understand the polymers and how they work.

Quotes source post: 9117450

I'd say you should try taking aggressive high speed turn with summer tires when the temps drop below freezing to find out but then you might end up hitting a tree and killing someone (or yourself). Suffice it to say, as others have pointed out, they pretty much turn into hockey pucks. They're pretty much useless regardless of precipitation. Add snow to the mix and you might as well have bald tires. -Eric

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I'm actually an engineer by training, but I deal with with material property issues frequently. But, come to think of it, I do less and less actual technical work these days Oh, and for what it's worth, I drive on my summer tires down to 20�F ambient or less. Just not if it's wet, icy, snowy, salty, or there is a chance of snow, sleet, or the risk of a single cloud. And I go easy.

Quotes source post: 9122506

Ahh, yes, many engineers around here - sadly few scientists that actually understand materials design. Common sense is the main thing to use. If people push their tires in conditions that they were not designed for, then they are going to end up in a ditch or attached to a light pole, but if they apply common sense, in using them judiciously in dry conditions, then there should not be an issue. I've seen more than one person describe tires as "hockey pucks" in cold conditions. That description is pure bull and misleading. As you see from the diagram I posted above, a tire is a very complex beast. Each one of those sections comprises of a different formulation and often different polymers (the reason that the Tg discussion is a red herring is because each of the many polymers in the tire has a different Tg and is not homogenous, plus each formulation has optimized mechanical properties imparted by it's formulation). It's a highly optimized system that is designed to work under the design conditions - that means that a summer tire does not work at it's optimum under winter conditions - does that mean that it turns hard and is useless? No, not at all, but it does mean that it has a fraction of the traction that it has under optimum conditions and people need to be aware and act accordingly.

Time to pull out the liability card...... First and foremost, it's selfish to decide to drive around in temperatures 45 or below without a winter-suitable compound on the car. We all know split second reaction times are sometimes necessary to avoid accidents. Think of others like you think of your kids. If you are following someone and they slam on the brakes and have winter tires are their car, and you don't you WILL hit them . How logical is the "nah, I'll be alright without them" attitude if you send someone to the hospital? If all other means of reasoning fails, think like a lawyer. And wrongful injury lawyers LOVE it when people in sports cars don't bother to take summer-only tires off in the winter. In Germany, insurance companies won't even cover claims if they find out the tires you chose to run were wrong. And, US insurance laws are likely close behind. This link has many snow tire FAQs in it. If you want to see snow tires in action, check out this . If there is still any doubt, you have to see this . Stay safe Rennlisters!

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As one of the people who referred to them as "hockey pucks" please let me respond. I never meant to suggest that the rubber compound actually turned into a hockey puck and I am happy to defer to any of the engineers on this forum as to what actually happens to the rubber when the tires get cold. From personal experience using a set of PS2s far deeper into the Winter than ever intended by Michelin (~10F), however, I will tell you that the car absolutely felt as though it was riding on...hockey pucks. Emergency braking and cornering grip were virtually non-existent at normal highway speeds (55mph) despite the roads being dry and the sky being sunny and clear. I also didn't call the tires "useless" because they didn't provide enough grip for me to drive aggressively. I deemed them useless because they provided less grip than I would expect from even a cheap all-season tire and barely provided enough grip to take a corner at (or near) posted speed limits. By my definition, that's useless. To each his/her own. -Eric

Well, I did use the car for a day and survived to tell about it. I was very cautious and fortunately, I drive mostly in the country so I was not in a high speed, high car concentration environment like a Chicago freeway. They felt fine, but I really didn't even come close to pushing the bubble and the p-car is now back in the shop building. I need to buy some winter tires, I can't stand not driving that car.... Damon, thanks for the links. Much appreciated.

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+1. I also called them hockey pucks, but that was to provide a visual image to help people understand that just because something is made of rubber doesn't mean it's soft and pliable. Hockey pucks are hard when they are warm too. I don't think anybody actually tried to convince somebody that the rubber was exactly the same as a hockey puck. I just wanted to help people understand that summer tires are not good in cold weather, even on dry pavement. I've personally experienced this, so I was just trying to pass it on. Not trying to mislead anyone...

Damn Dennis, I was ready to put hockey pucks on my Porsche, guess I won't now.

I'm going to a hockey game tonight... that's about as close as I'll get...

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I pity the fool who puts a hockey puck on (or anywhere near) my Porsche.

There will be no hockey near the C4S. We're headed down to the Pepsi Center to watch the Avalanche play the Tampa Bay Lightening. We're taking the Subaru.

If you have summer tires, and you drive the car once or twice in sunny dry winter cold, you should be fine as long as you: Don't have to stop quickly Don't have to avoid something in the road by swerving Don't have to turn quickly If you DO have to do any of the above, you are more likely to wreck your car than if you were using winter tires (or all season tires). You can get away with it on summer tires, but the feeling you get when you don't get away with it makes riding on the right kind of tires worth it!

Are you guys really saying not to drive your summer tires in cold weather? I understand that summer tires will be of little use on ice and snow but cold pavement? Guess I lived a charmed life with my Subie STI...

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In my mind it all depends on you're personal circumstances and how often you are driving your car. IMHO, if you are driving your car frequently and don't have alternates for bad weather, then you should spring for winter tires. If you're only driving occasionally on dry roads and not driving aggressively, then all should be well. It's all a matter of your personal risk assessment of whether the conditions and your driving style will cause an issue. I'm still weighing when to install the winter tires on my M3 - the forecast is still showing weather in the 50s and 60s for the next couple of weeks, but the fact that the morning temperatures will be in the upper 30's with chances of wet roads are making me inclined to do the install before I go back to work in the new year.

I know one thing for sure, when I go skiing to night, I'll be taking our Subi even though there are winter tires on the C4S. It's more of a matter of ground clearance than traction today!

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Summer tires, regardless of the car they're on (Subaru, Porsche, etc.), do not grip as well in temperatures below ~40�F regardless of whether the ground is wet or dry. I drove an STI some time in February 2005 (I remember the month because I was kindly asked to vacate my house (read: kicked out) because we were hosting a bridal shower). It was extremely easy to get the STI's wheels to spin and to get it to go sideways on dry roads. I knew what to expect but the dealer really should have warned me before handing over the keys and saying, "have fun!!" The experience between driving that car in the Summer and Winter on the same set of tires was night and day. If you don't notice a difference then your definition of "cold" and "Winter" are much different than in New England. I agree with you on "personal circumstances" but disagree entirely when it comes to "how often you are driving your car." If you're planning on going out even once and have no alternate means of transportation for driving in weather that is below freezing when there is a possibility of ice/rain, then you need the right boots on your feet....err...tires on your car. OR just don't use your car. As for driving in dry weather a few times when the temps drop into the 30-40 degree range, while I would slow down and be mindful of the Summer rubber, I probably wouldn't worry about getting an extra set of tires. I think we're in agreement on this, however, there is a big change in performance between a dry 30-40 degrees and a dry 10�F. If the temps are regularly in the 10-30�F range during the Winter and you plan on using your car in the Winter, then I'd invest in a set of proper Winter or, for those who don't like having 2 sets of tires, AS tires. -Eric