Still, people need to be disabused of their delusions sometimes, so here we go.
Winter tyres are for winter. They aren't special magic tyres for Arctic conditions. They are for winter - anytime the temperature is 7ºC or less, even on a dry road, you'll be much better off on winters. The tyres most Brits have on their cars are called "summer tyres". They aren't "normal tyres" or "road tyres", they are for summer, to maximise grip on warm road surfaces. And that means warm like Europe. I looked at the average max/min temperatures for Birmingham and conclude that we are better off on winter tyres October through May (inc) so if I could only afford one set of tyres, I'd be on winters year round.
Now, that ice thing. Here's a video:
By the way, by winters I mean, actual winter tyres. As per the video, all-season tyres don't even come close. Neither do M+S (mud and snow) tyres, or the big chunky tyres that came with your 4x4. The latter two are strong in some conditions, but do not have the general cold-weather stopping and steering performance of winter compounds.
So, four wheel drive. We need to talk about this. Four wheel drive can be a massive advantage in slippery conditions, or it can be a liability. If you're driving a Land Rover or 4x4 jeep or pickup truck like a Hilux then you are probably going to be doing better than most, even on shonky tyres. Same goes for a 4x4 car designed for rallying like the original Audi Quattro, the Mitzi Evo or Subaru Impreza, Lancia Delta Integrale, Sierra/Escort Cosworth, etc. Other 4x4's, not so much. Most of the other luxury 4x4's, the 4x4 SUV's and other random things, they don't have the right kind of technology for really slippy conditions. Basically if your 4x4 doesn't have the ability to lock (or seriously lim-slip) its diffs, including front to back, you're just going to get stuck the moment one wheel loses traction. Which is kind of worse than a two-wheel drive car.
|A soft-roader, faux-by-four, or as a friend put it, "Four by f-all"
If you don't understand what the hell I'm talking about above then you probably don't have the right kind of 4x4 for the snow and ice.
Having said all that, here's a disclaimer: winter tyres mean more grip in cold dry weather, in cool damp conditions and in the snow, and on ice. They are not a brain transplant or a cloak of invincibility. Do not drive like a twit.
To recap, here's a short list of things that don't seem to work terribly well in the winter:
and the brains of non-snow-dwellers, apparently.