I think they call those little teeth "Cutters" which do most the work while the blocky tread displaces and expels snow so the tread is clear for it's next contact with the ground.
These were my Avons
I took this photo in Argos carpark. The deep well cut in tracks were mine, The lighter, almost skimming over the surface tracks in front were from a Peugeot 307 on normal tyres, the wider ones going straight across were from a crewcab 4x4 type vehicle. All three were made in about 15 min of each other and there was no fresh snow falling to cover any sets of tracks.
They do cut in really well!
