Previous studies into wheel or tire disablements have examined either the physical effects of loose lug nuts, or vehicle dynamics following a disablement. This study investigates driver perception of loose lug nuts on the left rear wheel of a sedan. Testing was conducted in which a 2002 Mercury Grand Marquis was driven at various speeds through a course which included several turns, with the lug nuts tight and loose. The vehicle was instrumented to record steering wheel acceleration, steering wheel angle, and seat cushion acceleration. The driver was videotaped from the vehicle interior and the vehicle and wheel motion was videotaped from the vehicle exterior. In the test with loose lug nuts the left rear wheel separated from the vehicle. The driver's subjective observations indicated that the condition of the loose left rear wheel was not perceivable prior to wheel loss. Physical evidence on the vehicle components and roadway is described. There was no loss of control of the vehicle, nor did the vehicle suddenly change direction. The driver feedback data presented is compared to published studies regarding driver perception of tactile stimuli at the hand and on the seat. The peak accelerations and root-mean-squared acceleration in the seconds prior to wheel loss were consistent with the driver's perception that the loose wheel condition was undetectable prior to wheel loss.