[Edluver]

I recently noticed that when I'm driving at a speed greater than about 30mph I start to hear this odd hum. As I go faster, the pitch increases but not in volume. It's driving me CRAZY!!

I just got my right front tire patched and I'm wondering if that's it but I can't hear it if I roll down the window - wind noise is too loud. Is there any way it could be the rear diff?

Any ideas on what it could be, how to fix it or at least a way to tell if its coming from the diff?

Thanks in advance for the help.