Well, it looks like I am the 1 in 15 so far to pick the Nokian Hakkapeliitta studded tires. It was reviews like Nokian Hakkapeliitta
that convinced me. I have 2 miles of ranch roads that end in a 15%+ grade up to my garage. They are on a NE facing slope from 7,200 ft to 8,000 ft (800 ft elevation gain) and are typically packed powder most of the winter. Late March and early April are the freeze thaw time of year and I can end up with some pretty good soft and wet ice for several weeks. In town, Pagosa, and up to Wolf Creek, those icy conditions can happen any time of the winter. This winter will be a good test of the Model S in snow and ice, mountain driving with the best studded snow tires available.
See Up the Driveway at Hole-in-the-Wall – YouTube for a typical winter drive up in a 4WD Chevy Pickup in packed powder conditions.