If your google-fu is strong enough, you can find the actual code on line...but fenders, mud flaps, driving lights, and bumper height are all limited/controlled in Alberta.
As I recall, the reader's digest version is that you are supposed to have full coverage of your tires by your fenders (the fenders are supposed to stick out farther than the tires) and your rear tires are supposed to have mudflaps that extend at least halfway down the tire. I've seen guys run without either one of those things for years without any issues....and I've also seen tickets issued to some guys for not having mud flaps even when they had full fender coverage. I'd say that part of it is luck of the draw, and part of it is not giving cops any reason to pull you over....or not cheesing them off after they pull you over.
Like Johnny says - mudflaps seem to be the antidote to most "tire coverage" relate tickets, and they are easy to take off before you head onto the trail. Your mileage may vary.