From Tire Rack....
Priorities for Sizing Winter Tires Are Different
Does your sports car, coupe or sedan use wide, low profile tires that are mounted on large diameter wheels? Or does your light truck use large flotation-sized tires? If you're going to drive through lots of snow this year you'll want your winter tires and wheels in sizes that help put the laws of physics on your side.
A wide, low profile or large tire has to "plow" a wide path through snow which causes more resistance. The narrower the tire, the easier you can get through snow. We'll help verify sufficient load capacity and the appropriate diameter for your vehicle when you speak with one of our sales specialists or use
Winter Shop by Vehicle.
More here:
Winter Tech - Size Selection of Winter Tires
This doesn't specifically address ice, however.
If I measure both types of my 235/55/R17's on my S350 diesel, the winter tires are a full inch narrower than the summer tires. Same for my Land Rover Discovery Blizzaks vs. Michelins.
Some of these things can be counter intuitive. Personally I prefer to keep the cars looking the same and buy the next wider tire, which they've
always recommended against.