I have on occasion thought about running 31s, but a couple things are holding me back for now:
1. My Toyos are only a couple years old, and don't have much in the way of miles on them (not a DD anymore). Being the cheap bastard that I am, I didn't go to 30s until I wore out my last set (P225s), and would like to get my $$$'s worth out of these first.
2. With the stock 3.55s still in my axles, I'm concerned about it being too much of a dog on the highway when I take it to work (snowy days, for example). Yes, I could go to separate street/wheeling tires, but I don't have a place to put them and swapping them around would be a major PITA.
3. I keep hearing that you need at least 3" lift or fender trimming to clear 31s if you flex up a lot. I like my body too much to hack on it (rear quarters are another matter due to rust), and the current height is still accessible cleanly in work clothes.
Maybe down the road a little I might reconsider, but for now I want to see just how far I can go with what I've already got. After all, isn't that half the fun?
Rob