I checked out the rear wheel bearings and CV boot/shaft/ bearings on my audi A4 98' 1.8 (aeb) and they appear to be ok but there is still excess road noise. It sounds like a bearing problem of some sort but the wheel doesn't pull to either side so I don't think its a front wheel bearing....could it be a problem with one of the differentials? the sound oscillates somewhat at speed but doesn't change pitch

 

usually the sound will change pitch or will become less noisy if you are going around a corner at moderate speed when you have a bad wheel bearing. Also check your tires, see if they are getting cupped.

 

the tires have around 23 miles on them...maybe 25 tops. they are brand new firestone FR710s

I thought it might have been tire noise but it seems too loud

 

99A4NOW is right about the wheel bearing noise. Usually when you load up the side of the car with the bad bearing, as in a turn, the noise will get louder. If you turn right (as in a bend on the highway) and you hear the noise get louder, it's likely a bad bearing on the left side, as the left side is on the "outside" of the turn and the weight is shifting onto it. When you straighten out, the noise will die down some. Another problem that could cause noise like that would be a bad carrier bearing (the bearing that spins with the axle in the differential) - I had them go bad on my 300ZX. You said that yours doesn't change pitch at all, whereas the bad carrier bearings on the Z sounded like a low rumble at parking lot speeds, and built to an F1-like crescendo at highway speeds. You could also have a bad universal joint on a driveshaft - that'd be worth looking into.

 

I am having a very similar problem to but I am onlyhearing the noise around 55 to 60 MPH and up what speed are you getting the noise at.

 

all the way from 30 to 100+ it sucks