I tried a set of 31s before my lift, and they only would have rubbed in a turn if I hit a bump (or maybe without hitting something? I dunno). Again, my springs and everything were old, but there ya go. At that time, I chose to go with 30s.. But you might have better luck..
And now that I think of it, I really wouldn't have had much to worry about. They were on there for a few months and I stayed on the street... And now they're sitting in the shed out back.. DOH! Oh well...