Rear wheel noise

For the last few weeks I have had a low frequency hum coming from the rear of my 2008 gen2, witch seemed to be getting louder. My first thought was wheel bearing and to confirm my diagnosis I put a microphone into the tube of the trailing arm behind the rear wheel held in place by a piece of sponge, taking the cable into the car through the tailgate and plugging it into the aux in the centre console. Tried both sides and found no noise.Took both rear wheels off the car to find both tyres had worn on the inside shoulder, the left hand being the worst, but I also noticed the shoulder tread had sharp leading edges as when a wheel is out of track, but this was at 90% to the direction of rotation. I checked the rear camber with a home made tool to find drivers side (UK) at 2.5deg passengers side 3.5deg. I shimmed out the hubs with large diameter washers cut to a D shape to give clearance on the hubs and set the camber to .5deg on each side.
I had know problems with disc clearance as the callipers are fastend to the back plate and move with the hub,
The noise has now gone and he car handles much better.