Sorry, but I am moved to post again.
You guys just dont seem to have a clue how dangerous frozen motorways are. Chains are irrelevant, nobody is driving on the motorways in chains here. I dont remember the last time I saw somebody with chains (though they are compulsory on some small roads in Austria, I think).
I have driven up the Inn valley in a blizzard where I could hardly see 10 yards ahead of me, snow all over the motorway, unable to see the lanes, and lorries all wanting to go faster than I did.
Almost every day I've been out on the motorway in winter, it's been frozen. You can have bright sunshine and a seemingly dry road, that can STILL have ice on it, that lengthens your braking distance.
German drivers drive very fast and far too close together. They all have winter tyres. If you emulate them without winter tyres, you are just asking for trouble. People can come to a dead stop on the motorway, showing no lights at all, in the middle lane, with both other lanes flowing freely in these conditions. If you can't stop fast enough, you'll hit the back of them.
You can drive from good weather into a heavy snow shower, that turns the motorway into a skating rink within 30 seconds.
There is a certain sort of jelly-like slush that is fairly common here, that I've never seen in the UK, it is lethal.
And I repeat, if you dont have winter tyres, and you are involved in an accident, you WILL get blame, even if it wasn't your fault.