On the subject of winter tires; what do the Canadians recommend for the maximum age of winter tires?

Some here say to replace them after 4 years, but that is never actually stated by the manufactures. Mine are reaching 5 years from manufacture. Plenty to thread left and stored about 8-9 months a year in a temperature stable storage, on a tire rack that hangs them from the rims, with covers over each tire.

The cold is still a atleast a month away, so not switching over yet. Have stopped topping of the windshield washer fluid, so i can add the winter stuff without too much diluting it.