Yes, I know M3s can do amazing things in the snow w/o chains. They are required by law at the ski resorts I go to. Please don't turn this thread into one about whether chains or needed or not; too many other threads have gone in that direction.
(also posted on Bimmerfest)
I didn't find too much info on this when searching in the past, so I thought I'd share some info.
After looking around, the SCC Super Z6
snow cable seems to be the best choice for me. It's low profile (only 6.3 mm of clearance required), and on my second try (though it was my first attempt after reading the instructions
), it took me less than 2 minutes per tire. Cost is about $78.
I'm using them with my snow tires, which are 235/40 R18s. According to a tire size calculator online, the radius of the snow tires is 12.7 inches vs. 13.2 inches of the stock 19s. The difference is 0.5 inch, which is 12.7 mm. Since I'm only adding 6.3 mm to the radius, I should be doing fine.
But, obviously, there are calculations on a computer... and there is real world testing.
I haven't tried them in the snow yet, but I drove down the street a bit with them on. I couldn't hear any rubbing or scraping. I've included the best pics I could.
Hope this helps!