Rover 75 cdt - Single outer edge tyre wear - Geoffm

Hi

My problem is that the outer edge of the rear near side tyre is wearing a bald band, fronts are good and so is the rear off side so I'm at a loss to whats caused this. I have teken it into two well known tyre shops for tracking checks and both have said nothing can be done to adjust the rear wheel alignments it came out of the factory like it so the best thing to do is change the tyre every six months or when the tyre becomes illegal!

Surely something can be adjusted ? All help welcomed big time.

Thanks

Geoff