Have you checked whether the inside wall of the tyre is close to rubbing on anything.
I had similar symptoms on my 4/4 and it turned out the tyre could just make contact with the exhaust pipe under certain conditions, mainly on right hand bends.
Don't know how your exhaust is routed but the tyre could be close to something else if not the exhaust.
Don't know why it would go away when you touch the foot brake though.
