What is the silica tread compound? I dunno, I just read about it a little while back. I guess the first 50% of the rubber is impregnated with a silica compound that enhances traction in ice and snow, but I don't really know how it works.
I've never had problems with getting hung up on my Pacemark Snowtrakkers from Sam's club, so I just run those.
There's a bunch of different tires with the silica tread compound...Blizzaks, Dunlop Graspics, Artic Alpins (I can't remember who makes those)...just look up snow tires on Tirerack, everything that comes up except the Wintermaster are silica-compound tires.