And, I have recently learned, if you go to Les Schwab Tires (if you are in the right part of the country), you can buy a set of chains, then return them unused for a full refund.  So even if your trip to snow country is a one time deal, and you don't want to buy a set of chains, you can get some, then get your bucks back later.  And if you had to use them, at least you got unstuck... 
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OBG