To select a type of studded tire all you need to do is ask yourself two things.
How much snow does my region get?
0 - 8in = Mixed Terrain
8 - 12+in = Deep snow
What type of ground will I be riding on?
Bare Frozen Ground , Woods , Rocky Soil , Snow = Mixed Terrain
Soft Clay , Sand Loam and Motocross Tracks = Deep snow / Motocross
Mixed Terrain tires can be used in some deep snow and will work for motocross tracks it is an all around general use winter tire.