If you are going to be driving the ///M through the winter I would get a dedicated set of winter tires and wheels. Driving on summer tires through the winter is not ideal. I believe most summer tires are only good to about 40 degrees F. When the temps get lower than that those tires will get very hard and won't have much grip.
Getting a wheel/tire set will probably end up saving you money long term because you won't have to deal with mounting and balancing everytime you change over, plus 18" tires will be cheaper than 19". When I winter drove my ///M I ran a set of stock 18s (purchased here on the forums) and ran 245/40/18 and 255/40/18. You can pick up a set of stockers for like $800 on here. Plus you don't want to ruin your comp wheels.
I ran Dunlop Wintersport 3Ds.