Just checked the balance on the wheels. They were a little out so I re-balanced them. Didn't help at all, noise is still as loud as ever.

Tire wear doesn't appear to have any abnormalities. And as I said before, it still made the noise even with the wheels off the ground and the car stationary. So I'm convinced it has something to do with the drive train.

I guess I'll try replacing wheel bearings and axles until the sound (hopefully) goes away.

Any tips on checking for a bad cv axle?