I had this problem before and there are only a couple of possibilities, either the driver is very heavy causing the car to lean to one side. (I have seen this before). Or one of the alignment angles is off. I set mine up to have a little less castor on the left and a little more camber to compensate for road crown.

------------------
Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM