WHILE TRAVELING ON I-95 IN S.C. AT ABOUT 75 MPH A VEHICLE I WAS PASSING ENTERED THE PASSING LANE. I SWERVED SLIGHTLY ONTO THE LEFT SHOULDER & BRAKED. THE REAR WHEELS LOCKED BEFORE THE FRONT WHEELS CAUSING THE VEHICLE TO SPIN OUT OF CONTROL & ACROSS BOTH LANES OF TRAFFIC ONTO THE RIGHT SHOULDER. THE DEALER IN SC DID NOT SEEM TO THINK THE REAR WHEELS LOCKING BEFORE THE FRONT WAS A PROBLEM. AS WE WERE LUCKY ENOUGH TO AVOID BEING STRUCK BY ANY OTHER VEHICLES THE ONLY DAMAGE WAS FLAT SPOTS ON ALL 4 TIRES WHICH CAUSED A VIBRATION PROBLEM UNTIL THEY WERE REPLACED. NONREPORTABLE CRASH, NO INJURIES AN VEHICLE COULD BE DRIVEN FROM THE SCENE- THIS TIME! *JB