Loud road noise- bad wheel bearing?

2005 XLE Limited AWD: I have noticed that the road noise has gotten significantly worse in the last 6 months. I don't think it's the tires as they have been well inflated and still have about half their tread left. The noise gets very noticeable starting at 30 mph and gets louder with speed, and you can even feel the "grinding" vibration in the accelerator pedal and steering wheel. It's as though the bearings in the front wheels have lost their lubrication or something. I had an oil change and chassis lube done recently, no change. Any ideas what to look for or how to troubleshoot? I have the extended warranty, but my fear is that the dealer will say "that's just how it was made."