I had my front tires changed on 96 altima, and after few days I noticed that I was hearing a periodic loud chirp (bird-like) noise from the passenger side. The noise was most prominant when the windows were down and when going under a bridge or between closed spaces.
The pitch of the noise changed with the speed, and didnt seem to be related to engine or brakes.
After a couple of days of reading posts online, I concluded it might be time to spend some $$$ and get the possibly expensive fix. Just out of curiousity I inspected the tires and axels once more before taking the car to a mechanic and found out what was making this noise. The air-outlet on the right tire was brushing against the hub-cap (which was not properly aligned). I just removed and put back the hub cap properly and thats it.. it was that simple.
I thought I would post this just in case someone finds it useful... sometimes simplest of things can drive someone nuts :)