The BFG ATs should be able to take you to 50k miles. I know several people who have had these tires make it past 100k. In the summer I changed out a set of BFGs that had over 85k on them on my silverado. On the 4runner I am trying out a set of Hankook Dynapro ATm. So far I like them. They seem to grip well on ice. I just put these on in November and have over 8k on them already with no sign of wear yet.
85k on a set of BFG huh? thats pretty impressive. How were you about tire rotation?