You know oddly enough the 850 doesn't have the little Miles per hour marking on the inside. Many cars do here, guess not the Vo.
Well, I've only really driven the car in the States once, that was just from the Windsor boarder to the Detriot airport to go to Dallas. I tell you my 215/40/17 tires didn't like Detroit interstates... I felt a less choppy ride on a sea-doo! Well it didn't help I was doing 140km/h the whole way because we went the wrong way for half an hour!!! (sorry no mph conversion on that
haha, maybe, from what you said about your highways turning into virtual plate tectonics after the winter 16"s are the best of both worlds. Although I would maybe consider 17"s with 45 profile but it is more risky at that kind of dough. 16"s are a little cheaper, come in the same great styles and offer a plush ride. Most T-5s came with sixteens, and we've all seen our far share of damaged volans...
Roads here are pretty smooth in general and I find 17"s offer an exellent ride in most areas, actually feel the road more and seem to have more control on the highway compared to the 15"s, thats for sure.