Because I live in Ann Arbor, MI, where we're more likely to see Santa flying overhead than we are to see a plow or salt truck, I thought it prudent to buy real snow/ice tires instead of Porsche-approved performance winter tires as I ran previously on my 986. So far, the Michelins have been phenomenal. Dry grip and highway performance are acceptable, and they turn our 2010 Boxster into a snowmobile. PSM works perfectly with them to make snow driving painless. With the PSM off (of course I had to try it), it's got plenty of grip and right-foot restraint makes it manageable. I even have some grip on solid ice. I'm running slightly narrower than stock sizes, 225/45R-18 front and 245/45R-18 rear. The front/rear rolling diameter differential is within a third of a percent of the OEM spec Bridgestones, so the nonstandard sizes don't upset the PSM, which only expects the rear tires to make 3% fewer rotations than the fronts in a given distance (see revs per mile specs). The only downside I can see is that these aren't run-flats, so a puncture would end in a tow. Since I haven't had a flat tire in a decade and I plan on taking limited long trips on the winter tires, this is an acceptable risk for me.