yet another tire question, sorry

I'm not a tire guru, but I once read an article that ALL-SEASON tires (EVEN if they are snow rated) are NOT recommend at all for snow. Why? The rubber will have a very difficult "time" adjusting its composition to grip the snow. In other words, an all-season tire is only good for summer and mild rain; not for snow.

I also do not know the consequences of riding snow tires during the summer so i leave this question to others.

I'd recommend 195/60 tires.

 

I often visit family living in middletown springs and rutland, VT. I can't imagine living there relying on a Prius without snow tires. An all wheel drive jeep or even most front wheel drive vehicles, but not the Prius which is notorious for getting stuck more than most cars due to it's hypervigilant traction control and low ground clearance. On top of that, you missed out on the excellent VSC.

I believe Consumer Reports did a nice test a few years back comparing the some snow tires with all-seasons. Here's a couple tests from the TireRack comparing the ice traction of different types of tires.
http://www.tirerack.com/tires/tests/testDisplay.jsp?ttid=80
http://www.tirerack.com/tires/tests/testDisplay.jsp?ttid=64
There are some excellent European tests, like this one from Sweden: http://www.aftonbladet.se/vss/bil/story/0,...,709278,00.html. Nokian tires are understandably extremely popular in Vermont.

The advantage of dedicated snow and ice tires is snow and ice traction and safety unmatched by any all-season tires.

The disadvantages are higher total tire costs per mile or year and worse traction and handling (and probably worse ride and noise) than all season tires offer on clear or warm roads. The cost of winter tires becomes really bad if you don't change out of them as soon as winter ends. Studless snow tires wear very quickly, so the cost is higher than the price per tire suggests. Studded snow tires usually wear longer and offer great traction on ice and hard packed snow. They seem like a fine choice for you as they're legal in VT and you say noise isn't an issue. (Many find the noise of studded winter tires unbearable.)

If you're unconvinced that you'll want snow tires as you go from a jeep to a Prius, the TripleTreds are a fine choice. They might work ok for you when they're new and the tread is still really deep. If you're undecided after trying these in the winter, you might buy snow tires another winter when the tread on your TripleTreds has gotten shallow. I wouldn't use any Goodyear Eagle tire on a Prius in a Killington winter.

 

Tires do not "adjust their compound".. Their compound simply is what it is and it will either provide a degree of traction in ice/snow or it won't. It does not change with road conditions..

Basically the issues are: 1) compound and 2) tread design.
Rubber compounds can be formulated and manufactured for differing road conditions. In general there are hard compounds and soft compounds.. Hard compounds give you better tire wear and are generally best on dry pavement. Soft compounds wear away faster, but give better grip in most conditions. Additional things added to the rubber like silica, bits of walnut shell grit, etc and the use of porous rubbers, etc can improve grip in wet and ice as well.. For grip in snow, the tread design is more important than the compound. In general, you want a more "luggy" and aggressive tread design for snow traction, but these designs are very poor for most other conditions which need a smoother tread, so in fact, most "all season" tires tend to be designed as "3 season" tires- the tread and compound are designed for best performance on wet and dry pavement, but ice and snow performance are typically lacking.. There are tires like the GY TripleTred that claim that they have tread elements for all types of conditions, but the truth is that it's a bit more complicated than that.. The tread has to work together as a whole, no one single component can do all the work: for instance, they claim that the little strip down the centre of the tire is for ice grip, but if you think about it logically, there is absolutely no way in hell that a little 1/2" wide strip of tread down the centre of the tire is going to provide all the traction needed to stop a car moving on ice- this is all marketing BS. In reality, all elements of the tread have to work together, and there are always tradeoffs when this occurs... Optimal tire sizes for winter are a matter for debate.. It is normally recommended that you use the narrowest tire available for your car in snow as they can cut through snow more easily than a wide tire, but for ice grip, which generally relies on the compound, a wider tire gives you more tread surface to grip with.. In reality there's only about 1/2" of difference and you probably won't notice a difference either way and you should make your decision based on cost and availability..

If you live in an area where you get a lot of snow and especially ice on the roads, you really should look for a dedicated ice and snow tire. I've slid right through intersections on brand new all-seasons, and I can tell you that the difference between an average snow tire and even a top-of-the-line all-season is like night and day, and the premium winter tires are even better. Bear in mind however, that not even the best winter tire will let you drive like it was the middle of summer, but they do provide much surer traction on winter road surfaces. Having experienced the difference first hand, I can tell you that I will *NEVER* drive without dedicated winter tires again, no matter what the cost..

 

You could get Nokian WRs for general use. My experience with other vehicles is they are just fine in all but the very worst winter weather. In fact, we had an episode of very bad freezing rain last winter and I was able to get around just fine on my WRs, although I had to keep my speed way down. You'll find they wear very well, especially considering how well they work in rain and snow (60,000 mi treadwear guarantee).

That would take care of all but the worst winter conditions. Then, if you find they're not good enough for the very worst conditions, you can get true ice tires on steel wheels, or use the 4x4, though being a PU, in my experience it would be worse than the Prius. 4 wheel drive will get you going when 2 wheel drive will leave you spinning wheels, but you still have to stop, and a 4 wheel drive is heavier with less complient suspension, and can be a handful to stop! Especially a PU, with no weight in the rear! I've had SUVs forever, and I speak from experience.

 

As I said in my post, I use them on another vehicle (two actually). If any reader is using Nokians on their Prius (I know you're out there in the north east US ) please post your experiences re mileage. They are supposed to be LRR tires, so it shouldn't be bad.

I'm still waiting to get my Prius. Waiting for a vehicle to sell so I'll have room in the garage for it.

 

According to the Greenseal report (http://www.greenseal.org/resources/reports/CGR_tire_rollingresistance.pdf), many studless snow tires are LRR (low rolling resistance). They report is a few years old, but they cite winter tires from Dunlop, Bridgeston, and Michelin. Unfortunately the newer excellent study by the Transportation Research Board excluded data on winter tires (http://www.trb.org/publications/sr/SR286Rolling_Resistance_Data.pdf).

 

Do not get studded tires. They rip up the road, they have a narrow 'better traction' temperature range and generally have worse grip on wet or dry roads which, even in Vermont, is what you drive on 95% or more of the time if you are not on dirt roads. The colder it gets below freezing, the harder the ice, the less useful the studs. And we Vermonters all know 32F is a rare sight in winter.

I have TTs on my Prius, going into winter #3. I have not had problems and run them all year. However, there might be more steep roads in Killington and maybe they don't get to plowing the ones you need as quickly. My wife wants Hakka winters for her '06, now I just have to decide which ones. I'll be able to do a MPG comparison in a few months - OEM Goodyear Integrity (which she has now), her new Hakkas and my TTs. I don't think I took much of an MPG hit with the TTs but since there isn't anyway to do a scientific 'all other variables held constant' test, I have no hard facts. Even the switch from OEM to Hakkas will be hard as the MPG will be dropping with the temperature in a few weeks which is when the tires will get changed.

 

All season (M&S rated) tires are adequate for my SUV to get to Tahoe during a winter storm on a plowed Interstate 80, but inadequate for someone who drives in a true winter climate (i.e. temps so cold that typical tire compounds lose their grip).

The Snowflake (severe winter service) is more indicative of a tire that will perform well in true winter conditions: cold temps, snow, and ice. But now there are non-Winter tires that have gotten the snowflake rating. The Goodyear Fortera TripleTred (for SUVs, not the Assurance TripleTred for cars) has the snowflake rating but is an all-season tire with a long treadwear warranty. Either that tire performs really well on snow and ice, or the snowflake rating is not as meaningful as it once was. There are other light truck and SUV all-season tires that have the snowflake rating too. I'm not aware of any passenger car all-season tire that has achieved it, but I haven't checked closely.