If you plan on going to Whistler in the M3, then don't cheap out because there may be times where non-snow flake tires will not be allowed past Furry Creek.
Same goes for the local mountains.
I have all-weather Nokian's on my QX4 and while they do their job in the snow, they aren't the best and if there is any underlying ice, then they suck ballz.
Being up on SFU, I've seen many many SFU students in all sorts of cars and all the all season tire guys always manage to get stuck going up the hill or slide down and play bumper cars. With your M3 being rwd, you definately don't want anything that isn't a true snow tire especially if you plan on taking the car to the ski hills.
I have the General Altimax Arctic but with studs on my wife's CRV and found them to be very good when we had snow up on SFU but they will definately run like you are on pillows.
I'd highly recommend a sport winter tire. The sidewalls are stiffer so they will handle better in the dry and being a full snow tire, you should not be hassled at the check points.
Also, go down a size to 16's and run a narrower tire. Don't run 285/35/18's in the snow.
