I can vouche for the DWS's on the IS F as I had them on my stock rims and I cannot compliment these tires enough. Unfortunately, my purchase was short lived as about 800 miles later, I went with Vossens which called for 20 inch tires. If anyone is interested, let me know.Unless you live in the hot Southwest ... like me ... The Conti ExtremeContact DWS are amazing tires. Plus a long tread life, too.
Even though cars like the IS-F are unlikely to be used in heavy snow conditions, while the "S" is visible on the tread light-to-moderate snow can be conquered!
My son replaced the Bridgestones on his Mazdaspeed3 at 22,000 miles with the DWSs. Without changing his driving style the "S" is still visible after another 20,000 miles of Southeast and Midwest driving.