I was looking at this stuff last week. It seems the Trailhawk tire size is just very unusual. Based on the fact that I won't be doing any rock crawling, I decided I may be better off going with the Latitude with the 1.4L turbo and that way I can get the 6-speed manual too.
The standard tire size on the manual Latitude is 215/65/16, and there are a ton of A/T tires available in that size including both the Yokohama Geolandar and General Grabber AT2. I think the Grabbers look like the better tire (I love the more rugged look), but I'd have to do some reading to determine which is best. But either way, you seem to have a lot of choice at that size.