Alberta Tire Regulations

Tires must be matched in size and type on each axle. Tread depth minimum is .32 cm (1/8”) above wear bars, no baldness showing on adjacent treads is allowed. No part of the vehicle shall come within 2.54 cm (1 in.) of any part of the tire in any position of travel or turn. The minimum tread depth you should have on your tires at the commencement of winter is approximately 6/32″ (or 4.8mm). One way to measure this relatively easily is to use a typical Canadian quarter. Push the quarter into a tire tread (the caribou on the quarter should go in nose first). If the tire tread covers the tip of the nose, it is probably adequate. If not, you should replace your tires. There are no studded tire restrictions in Alberta also the province of Alberta does not make it mandatory for vehicles to be equipped with winter tires during the winter months. However, Alberta Transportation does recommend that driving in severe winter conditions that vehicles are equipped with four winter or all-weather tires for improved traction and control.

Source: http://www.transportation.alberta.ca/content/doctype45/production/commdriversguide2web.pdf
Source: http://www.qp.alberta.ca/documents/Regs/2009_122.pdf
Source: http://www.qp.alberta.ca/documents/Acts/t06.pdf