I have the stock sized Michelin X-Ice on our HiHy and they work fine going up the mountain passes. Back in October, my choices were already pretty limited, with Tirerack out of stock in our size (but got some more later in Nov), Costco tried to order some for me, but they were out of stock as well. I finally got mine through Discount Tire. There is also a Toyo and Dunlop snow tire in our size as well.
Here's an online retailer in Canada that shows they have inventory of snowtires in our size, its more expensive, but if you need them its there.
http://www.1010tire.com/tires.asp