I have recently had the rear brakes and the rear hubs changed a while ago plus the front and back springs changed at the same time plus the entire front control arms replaced on both sides just for peace of mind but recently on the motorway when accelerating and at cruising speed there is a loud humming sound coming from the rear sounds like a tyre rubbing I haven't had the chance to get it on a two post because it is lowered so I've been waiting for a chance to get it onto a 4 post could it be the bushings on one of the control arms have failed on the rear which is what I'm hoping it has got the RS6 rims with 235/40/18 tyres never had a problem until now plus one of the rims does look like it has negative camber but unsure