Modifiy the alignment... humm,.. You are on target, but the range is limited, however, worthwhile. Look, the car is sound. The wider the tire, the more tendency toward 'groove tracking'. If the car is solid , as to bushing, joints, bearings, etal then the tires are usually the issue. Sway bars - tower braces are great objectives when the vehicle is asked to turn. Tires and tire pressure may be closer to the 'cruising' issue on the decaying slabs of the interstate.