There are lots of electronic checks and adjustments on the 9-3. That may be causing extra wear if something is out of adjustment.
But the current car is a diesel. Was the previous car a diesel? Diesels are heavier. Also is your TTiD 180hp versus the 150hp (or similar) of the previous car.
His you tracking been checked? It may be out of alignment.
Has your tracking been adjusted? Is the steering wheel straight? If the car had adjustments on the steering, you should also get the steering angle sensor reset to straight ahead. Also if things are a bit out, the electronic stability may be confused and putting the brakes on on odd single wheels.
Are the tyres 225/45 17 94W XL (extra load)? If you have 225/45 17 91V standard load tyres they will wear quickly.