I've got a 1998 Accord Coupe with 180,000 miles.  Yesterday, the car started
making a loud droning noise which seems to be coming from the back wheels.
My first thought was I was driving on a low air pressure tire, but tire
pressure is fine.  It's a loud drone that gets louder the faster I go.  Like
the noise snow tires used to make when they were on a car or, sometimes the
noise you get when driving on certain grooved pavements.
Could it be a wheel bearing or something like that?  Tires are rotated every
7k and they were done 3k ago.

Any thoughts?