Thanks for your reply. I have style 223 on this car, and with the m-sport arches, a square setup looks kind of wonky, with a big gap.

Also, Tire Rack says if using the 255 50 19 in the rear, the tires must be run flats to satisfy the load index ratings. Interesting.

You're right, the 19'' selection is almost non existent for the staggered setup. There are maybe 3 tires to choose from at all. Swapping tires over and storing a set is a royal pain. But the peace of mind in the winter with a serious snow tire is worth it, I guess.