Steering and Handling Performance Following a Full Tire Tread Belt Separation 2012-01-0257

In this study, tests were performed with modified tires on twenty-two different vehicles to measure their steering and handling capacities with a fully separated tire. Vehicles were tested with delaminated tires (i.e. tires where the tread and upper steel belt were removed) placed on the front suspension as well as the rear. These tests were performed using open loop steering evaluations at highway speeds and according to the Society of Automotive Engineers procedure J266, which includes testing to measure the steering required to follow a circular path at ever increasing speeds until the limits of tire traction are exceeded. The SAE J266 one hundred foot circle test was performed with both good tires and with a front or rear tire that had a totally separated tread and upper belt. In the tests with good tires, the vehicles could achieve a maximum lateral acceleration in the range of 0.65 g to in excess of 0.80 g in both clockwise and counterclockwise directions. In constant radius testing with the missing tread tire on the rear suspension, the vehicles could achieve in the range of 0.50 to 0.75 g lateral acceleration in a turn with the separated tire on the inside or unloaded side of the vehicle. However, when the vehicle was driven in a turn with the separated tire on the rear and outside or loaded side of the vehicle, the lateral acceleration capacity of the vehicle was reduced and resulted in an oversteer related condition on all vehicles tested. When the delaminated tire was place on the front suspension, all vehicles experienced a significant increase in understeer and decreased cornering capacity with the separated tire on the outside of the turn. This study found that separated tires reduced the handling capacities and fundamentally changed each test vehicle's handling behavior. These results are vehicle independent and confirm all vehicles will have diminished capacity when such tire problems occur. However, all vehicle tested could be steered or braked to a stop with a delaminated tire at any position. Vehicle architecture changes such as vehicle type, drive option, wheelbase, and shock absorber location have no real effect on how a vehicle's handling characteristics change with separated tires.