Some manufacturers have got to the stage where the calipers are so big on the front wheels that the space saver spare won’t go over them. The fix in the event of a front wheel puncture is to remove the front and rear wheels on that side, put the rear on the front and the space saver on the rear. That’s not going to be at all unpleasant or dangerous on the motorway in the dark, is it? Don’t even get me started on how poor modern 385/20x21 rubber is in the snow, either. Back in the 80s, when we used to get snow every year, things like Fiestas on standard 145x12 rubber would go anywhere. Try that on 245/40s, you haven’t got a chance.
Next time out, when I get a car I want rather than just one that rolls, I’m getting a winter set of wheels. Smallest approved rim size, narrowest approved width, tall profile, winter tread profile.