Sounds like a wheel bearing, but it could still be the tire(s).
I had a constant tire noise for at least 6 mos. Turned out to be a cupped tire - a steady bup-bup-bup-bup...., etc., sound.
Sears gave me the run around, but there was a noticeable scalloping/cupping wear pattern on the tire that also could be felt with the hand. A newborn could have detected that!
The bad tire was eventually replaced, totally eliminating the sound problem. I don't understand why Sears blew-off my problem several times, especially in light of the recent Firestone litigation.
