I've just finished a stint w/ 245/45-16's on 16x7.5 35mm offset wheels. It handled quite nicely and the 45's were a good compromise between 50s & 40's, in the comfort department.
My concern w/ the stock 40mm offset wheels is the tire rubbing on the front strut where the tie rod mounts. W/ the 225 on the 40mm offset there is barely enough room (in fact there isn't enough) to slide a finger through at this point. Conversely, with the 245 on a 35mm wheel there was plenty of room to slide a finger through. I'd be hesitant about dropping the cash unless I could do a test fit to make sure they wouldn't rub.
Not sure in the 17s as a euro option, maybe Canada? That is what I plan on running when the big reds go on. Depending on how they ride, I may switch to 235/45-17 when it comes time for the next set.
Manufacturing tolerances, you gotta luv 'em. Your results may vary.