They also have special rubber that works at low temperatures (and wears quickly) and sometimes run spikes aswell.
Not really practical for a road going car however, although I do agree that the skinny tyres will aid the traction.
I have kept exactly the same alloys as my summer tyres so that if I were to be involved in an accident the insurance company couldn't turn around and say that I didn't have the right size wheels/ tyres on the car at the time.
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Just an update
About 3 inches of snow this morning and not a
problem on any of the hills or getting traction. Only thing I have to remember is the backs are not as good in these conditions so keep it very steady on the corners. However if it does step out I have the traction to give it a bit of power and pull it back in.
A pair for the rears is the next step but as every where is out of stock it will have to wait for a while.