My old 1997 M3 4dr enjoying a blast through the snow. Proper snows and a limited slip differential made this fun rather than scary.
Our family lives in New England, Connecticut to be precise. So we usually have a pretty snowy winter that tends to run November to April, give or take a month. We have a bunch of cars here and all of the "dailies" get snows put on in the winter. My car, my wife's car, & my kid's cars all have snows on them right now. (January) All but the Audi have a 2nd set of wheels that have snows mounted. It takes about 30 minutes to change them out now that I have a quick jack. An hour a year, per car. Not too bad. The Audi wheels are expensive so I re-use the same wheel and have a garage mount them in the late fall.
All of our primary "dailies" have all wheel drive.
The "fun cars" are all real wheel drive.
We live in a fairly hilly area and having AWD is really helpful. One of the worst calls I ever got was Mrs P calling to tell me that our Volvo T5 wagon had slid backwards down the driveway and into the woods with her and our 2 young kids in it. It had good snows, but it was front wheel drive with a standard differential so all that power went to one front wheel. I came home, got it out of the woods and then we traded it in for an XC70. We were very lucky no one was hurt. In fairness, it was really a worst case; weight transfers backwards both when accelerating and when going uphill, which took weight off the front tires until they just couldn't do much, and the snow and ice finished the job.
So, why snows?
There are a bunch of reasons, but let me see how short I can keep this:
Summer tires and winter tires are solving very different problems. They use different rubber compounds & different tread patterns to be optimized for their environment. If you watch racing at all, you know that race cars run on slicks (no tread, just very sticky rubber) in the dry and come in for rain tires when it rains. This is the same idea; they are solving different problems and running at different temperatures. Everything is a compromise, or as my mentor loved to say, "Ain't no such thing as a free lunch". Snow and ice tires are very different across the board from warm weather tires or all seasons, and that is a good thing.
Snows are inexpensive, and tend to last 2-3 seasons. For around $500 or less, you can get 4 of them and protect your loved ones and your car. That is 5-6 months a year for 2-3 years. At worst (5 months a year for 2 years @ $500) that is 304 days of use at $0.61 a day. Even a small accident is likely to run >$1,000 in damage, and worse could hurt someone. It only has to save you once to be worth it. If you commute every day through all kinds of weather, it's just a really good idea. You spend more on your morning coffee probably. As a side benefit, they will make your all seasons last up to twice as long.
"But I have all seasons already" All seasons are a wide ranging compromise. They are less good in the dry, less good in the wet and less good in the snow and ice. They will be ok at everything. On the plus side, it's just one set of tires to deal with. But if you get stuck in a storm, you're going to have a bad experience. If that is a concern, look for a set of snows.
"I have all wheel drive" Two questions to ask there: first is do you actually have all wheel drive, or are you turning one front wheel and one rear wheel? (very common). And second, do you have to manually activate all wheel drive?
Many SUVs look like they have AWD but they do not. We used to have a Ford Explorer. A limited slip was not standard; it was only available if you bought the towing package. Explorers were sold in 2WD, and 4WD models and the 4WD had to be manually activated. Some systems, like Audi's Quattro and Subaru's AWD system do drive all 4 wheels all the time with various tech to allow the systems to correct for wheels slipping. And they can be more expensive as a result. Ultimately if you can't put power to a wheel, it cannot help you move.
"I have traction control so I don't need them" If you do not have traction to control, it's not going to help. I hope that is intuitive. You need tires that will stick to the surface you are driving on. Then it can do something. And that "sticking" helps you start, stop and turn.
I cannot use my summer tires in cold weather (eg: the Audi). They will be damaged by the cold, even to the point of failing. (did you know that rubber freezes? It does.) Typically 40 degrees F / 4 deg C is the cutoff. Your dedicated summer tires are designed to stick to the road in warm weather. In cold weather, they will get hard and slippery and possibly have a structural failure if you push them in really cold weather. This is generally a sports car problem, but something to be aware of. All tires are busy managing heat, which comes roughly down to traction vs tire life.
Adjacent: Studded tires & chains
There are 'next level' options for folks that live in very snowy areas such as the mountains. Tire studs are little metal 'cleats' that basically screw into your tires. Their legality varies by state; they are not much good on dry pavement and can cause an excess of wear to the roads so they are generally prohibited during warm parts of the year.
Chains come in a variety of flavors. These are systems you attach to your tires, usually some combination of fabric and metal to help with traction in extreme conditions. Once again, they are poor in other conditions, not great for the roads and in extreme cases they can damage your vehicle. You will want to check with your manufacturer to see if your car can take chains, and if there are an approved set for your car or SUV. There are also areas that may require them depending on weather. Check ahead.
Things to look for when you shop for cars:
If it is 2 wheel drive, look for a limited slip. These may only be available with a sport package in cars or a towing/off-road package in SUVs. A limited slip simply means that the car wants to turn both tires at whichever end of the car it powers (front or rear) and will not allow them to spin at very different speeds (that is the "limited" part of limited slip) We've all seen stuck cars spinning one tire. That's an open differential, it's the standard because it is simple and inexpensive. But you get twice the traction turning both tires. It's a huge difference. It is hard to overstate what a big difference it is. It even saved Ralph Macchio in "My Cousin Vinny". (It is also known as 'posi-traction' but that is a brand name owned by GM for a limited slip differential)
If it is AWD, pay attention to how the system works and what it is actually doing. Audi & Subaru both use various techniques to control how power gets to the wheels. Both mfrs have systems that are on all the time. Subaru actually ships 4 different AWD systems depending on the specific vehicle you purchase. The top of the line WRX-STi has limited slip differentials front and rear, and a 3rd in between the front and rear. Audi's quattro uses a similar system to the WRX STi to send torque to any or all of the 4 wheels at any time depending on conditions. For contrast, many "AWD" systems are simply using open differentials at each end of the car and so you are turning one front and one rear tire and there is no allowance to adjust which is getting more power. Further, in many SUVs you have to turn on AWD; they will run in RWD (2 wheel drive) to save gas otherwise.
In our old Explorer we had to turn a knob while stopped to turn it on, and then stop, turn the knob and drive backwards about 10 feet to turn it off. That was a few years back, but it an example of what kinds of systems are out there.
Just get the details up front so you know what to expect. Don't assume the salesperson knows how it works. Many auto mfrs have offered systems since Audi pioneered the concept in passenger cars. VW, Volvo, BMW, Toyota, Honda, Mercedes, Nissan & Mitsubishi all have their own. (VW has some cross-over with Porsche & Audi depending on the vehicle in question) There are lots of options, technology and features. It can get confusing. Just take your time and ask these questions to help (hopefully!) clear things up.
Reference:
How to choose snow tires https://www.lesschwab.com/article/how-to-choose-snow-tires.html#:~:text=Summer%20and%20all%2Dseason%20tires,more%20pliable%20in%20winter%20weather.
Winter tire markings/ratings: https://www.tires-easy.com/blog/mountainsnowflake-symbol/
Limited Slip Differential: https://en.wikipedia.org/wiki/Limited-slip_differential
Standard Differentials: https://en.wikipedia.org/wiki/Differential_(mechanical_device)
Studded Tire Legality: https://www.ustires.org/studded-snow-tire-regulations-passenger-cars
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