Mismatched tires would be my first idea as to the problem. Radials on the front and Mickeys on the rear is a disaster for handling. All the tire manufacturers (Michelin,Dunlop,Mickey) will tell you if you are running a mismatched set the radials need to be on the rear. If that is not the case the steering wheel not centered could be a clue. Since the pitman can only line up one way on the box shaft, the wheel should be centered unless one side tie rod length is longer to make the wheels appear to be pointing straight. One side longer tie rod length will make that side tire in jounce(extension) tilt in from the top and steer you sharply that way.