I was researching the BFG AT KO's at Tire Rack and noticed they made a point about saying size 275-70-18 is not rated for severe snow. Some of the other popular Tundra sizes are, such as 285-65-18 and 305-65-18. I don't get it. The tread depths are the same. Also, 265-65-18 is, so it's not the narrower width. Anybody know why this is? Maybe they just didn't bother to test this size, so it's not rated.