I'm in a similar dilemma. I want to get the 20" wheels and need to stay with Runflats because of not having any room for a spare with the 3rd row seats (at this time the only Runflat tires in those specific sizes are summer tires). I live in Los Angeles and we obviously have no snow here and hardly any times where the temperature is close to freezing, so the 20" summer runflats would be OK here. However, sometimes we do go to skiing resorts one or possibly two days max. a year....and even then most of the times the roads are clear of snow. So is it worth for me to consider getting 19" wheels instead of the 20's so that I could get M+S tires for the 1 or 2 days a year that we may be in snow? Would chains not work well enough in that situation for us?
Here are some chain options I found for the 315/35-20 tires. Their prices range from $73 to $425.
Spikes Spider ($425):
http://www.spikes-spiders.com/catalo...tegory/?id=598
Farad SNOW tyre crampons (£144.85): http://www.roofbox.co.uk/scripts/rbv...Tyre=315/35-20
SCC Super Z6 Chain ($73):
http://www.amazon.com/Security-Chain...668311&sr=8-13
