If your getting wear on the outside edge but not on the inside, that really sounds like a Camber issue. If you know your alignment is good, then toeing it out might help some. But that is only if the toe on the rear is toeing in while your riding down the road. It might be possible that you toe is slightly out of spec, or in spec but toed in a bit. One thing that most people don't know is that most German cars alignments are to be done with special tools to simulate driving conditions. Most techs, including myself, don't have the tools to get it just right so some cars will not align perfectly. For example, I remember that the correct way to align a BMW was to put 50 kilos in both front seats, a certain amount of weight in the rear, a toe bar in between the front tires pushing out, and it was suppose to have a half a tank of gas.

I consider myself to be a darn good alignment tech, but I just really picked up on the amount of crown on the roads in the area that I worked and kinda had my own little tricks that seemed to work in aligning German cars.

Now to get back to you, I would recommend checking the amount of air that is in your tires and see if its running low. That would make you ride on the outside edges of the tire and could add some excessive wear when cornering. Also look at the way you drive. If you take corners kinda quick regularly, then you can show some excessive outer wear due to the fact that our cars ride on low profile tires. This can be even more noticeable if your tires have a low tread wear. If your running the Michelin Pilot Sport PS2 tire, then your tread wear is kinda low and taking turns fast will easily wear the edges out compared to the Continental ContiTouringContact CW95, which is the other all weather OEM fit tires, which have a much higher tread wear.