I see that you bought a set which is always smart to have, but for those that are traveling and want to have a set "just in case". Les Schwab Tires (stores all over western states) offers a purchase program where they will give a full refund any time if the boxes are still unopened. Never used it myself but might be handy if this is for one trip only.
I think you can't return them until spring, like sometime in April. I think they count on you losing your receipt by then.
