.I see no problem with a 17in if it is lighter than stock and you have went up in rim, down in tire, overall not enough change to adversely affect the car.I use this tire size calculator to see how different sizes relate to the stock and how close overall diameters are. The 205/40/16s I think would be no problem on the stock wheels and yes there is a lot more choice in that size for sure.
I went with 175/65/14 for snows. Same diameter as stock 16's and nice and skinny for the winter. Better selection of quality winter tires in this size also.I personally would love to have a set of summer tires as wide as i can go and some really thin winter tires and would like to know what sizes work.