General Maintenance & Repairs - What might this wa-wa-wa noise be?

For about 1-2 weeks now I've had a low frequency wa-wa-wa noise (reminds me of a helicopter blades at slow speed) inside the cabin. The noise seems to start above 20-30MPH, then gets faster as the speed increases. The speedometer seems to flutter a little as speed approaches 60MPH.

I've checked tire pressure and lugnut torque. Because of recent surgery I wasn't able to get under the vehicle to perform a complete tire wear check, but I didn't see/feel anything while it was parked.

Can a failing wheel hub, axle bearing, u-joint, driveshaft, or differential cause this? I just assumed it was the differential until I noticed the fluttering MPH needle on the dash.

Check the differential.

Uneven tire wear and/or bad wheel/axle/pinion bearings are all possibilities. More than likey, it is a bearing in the rear end.

It was the RF wheel hub. We replaced both this morning and the noise is gone. I've had play in the hubs in the past but it never was audible. This will probably be the last time I use 315's on a daily driver due to fuel economy and accelerated wear on parts :) Thanks for the help guys!