THIS 2000 FORD EXPEDITION IS USED AS AN EMERGENCY RESPONSE VEHICLE OPERATED BY PARAMEDICS RESPONDING TO 911 CALLS FOR MEDICAL ASSISTANCE. DURING ROUTINE DRIVING, A PARAMEDIC REPORTED A SUDDEN GRINDING NOISE IN THE FRONT END. HE WAS RETURNING TO THE STATION WHEN THE FRONT RIGHT WHEEL (TIRE AND RIM) CAME OFF. ALL FIVE POSTS WERE SHEERED OFF. VEHICLE UNDERGOES RIGOROUS MAINTENANCE, AND NO PREVIOUS ISSUES WERE REPORTED.