I live in Iowa and Drive in Illinois. Winters and Illinois roads suck. While I love the look of low profile tires. They just can't handle the horrible roads of Illinois. Low profile tires and crappy roads do not mix. I've had problems every winter with air leaks. I've also bent two rims on pot holes. So after doing some calculations on tire circumference. It looks like 205r/55-16 have identical revolutions per mile as the 215r/40-18. What I'm not sure of is rotor clearance on my 2013 nav with manual transmission. Anyone out there slapped on a set of 16's?.