you need to jack it up to isolate it. if you say it vibrates all the time, it has to do with the axles or a wheel bearing. i think its a wheel bearing. but like i said, jack it up, wiggle the tires up and down and side to side. shake your axles with your hand and see if it has lots of play.

i still think its a bearing. if its a brake issue, then vibration should only happen during braking. in my experience, when i see a bad bearing, evry time, the rotor will be warped as well on that side wiht the bad bearing.