fyi bad wheel bearing
 

Just thought I would share a lil fyi about my wheel bearing. When I first bought my 01 cherokee I took it on a 1500 mile trip all around michigan.

After about 20 minutes of driving you could hear a sound that was like a hum kinda like how a bad pinion bearing sounds(thought it was this at first) I jacked it up 3 differant times and the wheel was rock solid every time.(another reason I thought it might have been the pinion, sounded just like when my mustang pinion went)

Once I got home I eventually changed the wheel bearing and the sound went away. So even if the wheel is solid when you check it, it can still be the bearing.