After two garages thought the noise from the rear of my Signum was the early stages of bearing wear I was told to continue driving until the wear was so evident that they could identify which bearing it was. After a few thousand miles more, the noise was excessive and took it to a third garage who found that the tread blocks were wearing unevenly on the inside edge of both rear tyres. Mechanic thought it a tyre fault, tyre supplier said it was not uncommon for the car to show this tread block wear. Also happens to some Seat models he reckons. My tyres show one tread block normal wear one deeper wear, sometimes one block normal two block deeper wear. So check inside edge of rear tyres for this uneven wear pattern.
Parnas, October 2009