We have been in ice conditions for several months continuously in Fairbanks. Today the temperature may go to 5 below and it is snowing a little. Yesterday the snow was falling in large flakes, today it is falling in tiny flakes and the quality is very different. There is wind today and some fogginess in the air as well. Just right to go out driving. For traction on smooth ice you need the smallest contact so the pressure of the weight is on the smallest portion of surface possible. The ice will liquify at that point, but that is also the reason for increased traction: the surface of the the ice nelts and a small crater forms instantly, and the edges of the crater provide what traction there is. If the ice is rough already, then a soft tire compound will let the tread conform to the existing irregularities and it is similar to a gear-driven machine.