2Safety Engineering and Forensic Analysis, Inc., USA
A 2004 Chevrolet Tahoe was tested with the Original Equipment Manufacturer’s (OEM) base and optional recommended tires and wheels, and two sets of different sized aftermarket tires and wheels. One aftermarket tire and wheel set used a much larger and wider rim with a low profile tire that did not significantly change the vehicle’s Static Stability Factor (SSF). The second aftermarket tire and wheel set used the larger optional OEM rim with a larger than recommended Light Truck (LT) designated tire that significantly lowered the vehicle’s SSF. Tests were performed pursuant to the protocols described in the United States Department of Transportation (USDOT) National Highway Traffic Safety Administration (NHTSA) New Car Assessment Program’s (NCAP) fishhook and sine-with-dwell maneuvers. Results demonstrated that changes in vehicle performance due to the use of aftermarket tires were dramatic. The lower profile tire and wheel combination produced vehicle tip-up in fishhook testing at 40 and 35 mph with and without ESC enabled respectively. The larger LT tire and wheel combination did not produce vehicle tip-up in fishhook testing with ESC enabled, but did at 45 mph with ESC disabled. Both base and optional OEM tires produced test results which fell in between the two aftermarket tires. The vehicle successfully completed the sine-with-dwell test maneuvers with ESC enabled and failed with ESC disabled when equipped with either the base or optional OEM tires.