Thx. I've not done anything on the rear. not checked the oil and actually did not know the wheels even had bearings .
When I open the window to listen, I cant hear the noise, so it may be something underneath, like you say. I switched the fronts and will know tomorrow if that changes anything.
The tires are a year old and my DIY alignment is a little older. I started noticing the noise a month or two ago, I think.

https://photos.google.com/photo/AF1Q...jywg_blOw1HlaI

Edit: switching tires changed nothing.
The sound I'm hearing is similar to blowing over the top of be a coke bottle, repeatedly.

 

I'v concluded the noise is coming from air blowing over and through the fixes I've made over the years to my front end after at least three DIY repairs. Grill, bumper, bafffle, Come-along on the frame, too-big tires... after a while I guess it just adds up to road noise.

 

Those push nuts are just factory assembly aids. They keep the rotor from falling off, and make installing the brakes a little bit faster.
Once the wheel's installed, the rotor is squeezed tight up against the flange.