September 28, 2009 by markarndt
Given knowledge of the dangers, the notion that tire failures occur on vehicles traveling at highway speeds is frightening. Yet, such failures occur and the general acceptance of tire failure is so deeply rooted in vehicle performance that spare tires are standard equipment.
A specific rollover incident in which a rear tire tread separation caused tearing apart of a fuel tank fill pipe routed just behind the wheel well was recreated in a controlled test (watch video). The incident resulted in fuel spillage, fire and burn injuries. The October 2001 incident
involved a 1995 Land Rover Discovery with a General AmeriStar tire failure. The vehicle manufacture’s corporate representatives were shown the test in late 2002 during depositions.
High speed video captured contact between tire tread and reinforced rubber fuel hose as the flailing end of the tread separates from the tire. Repeated contacts by the tread to the fill pipe fuel hose and vehicle underbody result in fill pipe failure and release of liquid from the fuel tank. Tests of a peer vehicle did not produce a failure or leakage.
Regarding vehicle handling and tire tread separation, failures a relationship between vehicle design and loss of control is scientifically documented. Only recently has an incremental improvement in vehicle handling following tire tread separation been demonstrated with Electronic Stability Control (ESC). Regarding other aspects of vehicle performance in tire failures, specifically including tire tread separations, dangers exist that can enhance the chance of harm.
It is a well know consequence of tire failures that the tire tread can damage the vehicle. In tire tread separations substantial damage to the wheel well sheet metal is probable. Tire tread failure induced damage has been documented to hydraulic brake lines, parking brake cables, tail lights, fuel fill pipes, wiring and bumpers. Parts of a car, not to mention the tire tread, can be knocked free and onto the road surface. Vibrations from a tire failure have tripped inertially activated fuel pump cut off switches resulting in unexpected engine cut-off.
Engineers can readily foresee similar scenarios for a variety of safety equipment that is taken for granted in motor vehicles. For example:
A tire tread separation occurs at night, damages wiring that routes near the wheel well and renders driver’s suddenly blind to the road or hazards on the road,
A tread separation causes permanent damage to hydraulic brake lines or parking brake cables resulting in brake failure or compromised performance.
A tread separation causes damage to a light cover or reflector, often rear taillight breakage is observed.
That these are important events in a vehicle’s safety performance is simply supported by the fact that Federal Motor Vehicle Safety Standards (FMVSS) regulate the performance of vehicle systems that are directly dependent upon the key components described above.
A tire failure event could be analogous to the Part 581 Bumper Standard. Low speed, often parking related, bumper contacts occur in normal driving. Comparatively, tire failures are also expected – driving manuals instruct how to react to a tire failure and most cars have spare tires. Anticipating low speed contacts, the Part 582 Bumper Standard covering all passenger motor vehicles sold in the United States prescribes protective criteria for: lamps, reflective devices and head light alignment; operation of doors; fueling and cooling systems; propulsion, suspension, steering and braking systems; impact energy absorbers; fasteners and joints; and, even separations of surface material, paints and coatings and permanent deviations of original contours. Comparatively, following a tire failure a vehicle should be capable of performing at the minimum level of safety prescribed by applicable FMVSS. Vehicle design interventions can effectively eliminate dangers from tire failures induced vehicle component damage.
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