I agree with people who say "There is no best tire; it depends on the situation", so here's my situation:
I live in LA, where it's perfectly fine to use summer performance tires all year round. As much as I'd like to go more often, I only go snowboarding a few times per year. When I do go to the mountains (115 miles to Big Bear, 350 miles to Tahoe), all but the last 10 miles or so are on perfectly clear, dry, and warm (temps around 50-75F) roads. In fact, driving up to Tahoe, I'm generally be able to safely drive around 80-90 mph most of the way.
However, the last 10 miles on summer performance tires can sometimes be perfectly fine... or downright scary and I'll never know which it's going to be at the moment I leave my house.
- Continue to use Summer tires: I've done this for years in my previous cars, and have never had an accident. But, as I get older, more cautious, and own more expensive cars, this idea doesn't appeal to me so much.
- Rent an SUV. I've done this a couple of times. The problem is that I LOVE my car. I also hate having to drive 700 miles roundtrip in some lame SUV on a clear open road when I have an M3 in the garage.
- Buy a 2nd set of wheels/tires that I ONLY swap on for a trip, and then immediately go back to my regular tires. This means I'll be buying a set to only use for about 6 days per year - not the wisest use of $$
If I go with Option 3, I'm looking for the cheapest tires that do the job well. Long term wear doesn't matter too much, since I won't be doing that many miles on them.
The cheapest tires in the "snow" category that will work for me are the Blizzak WS60 ($600 after rebate) but are "Studless Ice/Snow" tires vs. the cheapest "Performance Snow" is around $750 after rebate.
Given my driving situation, should I buy the V-rated Performance Snow tires vs. the R-rated (max 99mph) Snow/Ice tires. Will the warm weather of SoCal cause the Snow/Ice tires to perform poorly or show extreme wear? Or, since I'm only putting the snow/ice tires on for the days I need them, is it actually better to have the best possible snow/ice traction vs. Performance Snow tires, since they are maybe made for people who need them every day?