Car is pulling right .. please help

[glamcem]

After i purchased the new set of tires (goodyear eagle F1 GSD3s) took it to the Sears and had an alingnment ..and i noticed that the car was pulling right(slightly but it was still there) ,took the car back and asked them about that ,they told me they did the alignment properly but i wasn't convinced so i 've got full refund and took my car to the local chevy dealership ..service guy looked at the print out told me the alignment is fine ,took the car out for a test drive and said "car is slighlty moving to the right , it might be road crown .. i wouldn't bother" .. he also told me that he had a mustang and his car is doing the same thing ..is that really normal? the reason i'm asking you is b/c i drove the wife's car (subaru impreza)on the same exact road and it seemed like it was going straight unlike my Z...is it because i got wider tires and it makes that road crown pull more obvious?then again it's not pulling like crazy but it's so annoying..thanks in advance