2000 XJ Front end noise

I have had my 2000 Jeep Cherokee for 2 years now.  I put a LOT of miles on it.  What your average driver puts on in a year I do in a few months.  I have put probably 60k miles on it in the 2 years I have owned it.  It sees mostly highway speeds and highway driving.  I have a rumbling or humming noise comming from the front.  My mechanic tells me it's my tires.  I have Bridgestone Dueler AT Revo's on it.  They aren't worn out and I don't see any strange wear patterns.  I don't think it is a wheel bearing because it doesn't get louder in hard cornering on country roads.  I have also noticed when I am in a parking lot or turning around the front end seems to, for lack of a better word, bind up a lot like when it is in 4WD but I'm not.  Maybe I'm crazy or maybe I just notice these things before they get really really bad because I live in my car and travel a lot in my jeep.  I'm getting frustrated with this noise and it has become very demoralizing and I want to get any bugs worked out before I got lifting it and adding other mods.  Any help would be much appreciated.