The screw was the first thing I noticed. Maybe it's because I just pulled a bloody nail out of my bike tire today, that might have been why I was focused on it...
I once ran studs on some very tall snow tires on an old Coronet that I drove many years ago and that thing would climb up the side of a barn with no trouble at all. As you say, they frown on these things around Vancouver and I really don't blame them. I'll probably check out the wreckers for some rims soon and then spring for some of these new age winter tires soon. Enjoy your winter over in Alberta - you've already had a few good dumps of snow from what I've been hearing.