Narrower is better in real snow like we can get (some years) in Ottawa. Also, don't even think of using only two snow tires, like some tire-shop conehead advised my wife in her Ford Tempo days. Scary!

Ours is a 945 so details may be different, but we got "hub-centric" wheels specific to the Volvo from an aftermarket supplier through Frisby Tire. They were well under half the price of steel wheels from Volvo, and are practically identical. I am happy with the Yokohama Guardex 600's I got from Treff's Tire, but cannot honestly compare with other modern snows for you. Consider taking the time to swap the wheels yourself when required - you get to control wheel bolt torque and inspect your brakes and suspension at the same time.

On the subject of wheel covers, ignore those on this site who have no idea what real winter can do to a car. Go naked if you don't mind the raw, brutal look it gives your car. Or, fork over 40 bucks CDN for a set of four 15" wheel covers from Canadian Tire next time they are on sale, which should be soon. They come in several styles and are better than the 60 dollars (each!) Volvo items that came on our car. I happen to like the cheapies I got and use them all year.

Brian in Ottawa