Wheel separations are rare, but do occur, said Lickert, who has investigated a half-dozen similar incidents as a crash reconstructionist for 38 years, first with the Dayton Police Department and now with Law-Science Technologies in West Milton.
“The problem with pneumatic tires is they are just unpredictable. You don’t know where they are going to go,” he said. “Sometimes they bounce really high. And most of the time they bounce across the median.”
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Each year, dozens of Ohioans are killed or injured on roadways in incidents that defy norms, caused by shifting cargo, fire, water immersion, animals and others.
Of the state’s 1,094 traffic fatalities last year, 486 died in collisions with other vehicles and another 82 drove cars off the road, 64 hit trees, 48 rolled vehicles. But another 16 ran into parked vehicles, eight died hitting mailboxes, three fire hydrants and one each a deer and farm animal. Just two died from equipment failure like a blown tire or bad brakes during 2017, according to the Ohio Department of Transportation.
Lt. Robert Sellers of the Ohio State Highway Patrol said
drivers can let others know of roadway obstacles or unsafe loads and malfunctioning equipment on another vehicle if it doesn’t create a more dangerous situation, Sellers said.
“If you can safely signal others to avoid a hazardous situation, you are contributing to safer roads in Ohio,” he said.
Lickert said Tester’s is the first area death he can recall caused by a wheel leaving a passenger vehicle. More often, the wheels that cause injuries and fatalities have separated from truck trailers, he said.
“All the ones I’ve had in the past have been commercial vehicles as a result of improper maintenance and the bearings burning up and snapping the axles off,” he said.
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But passenger vehicle wheels are more likely to come off due to a different problem, said John Glennon, a forensic automotive technologist in Lenexa, Kansas.
“The problem that we see over and over again that’s responsible for the vast majority of wheel runoffs can be characterized as abuse of the mounting hardware,” he said.
Otherwise over-tightening lug nuts, he said.
Tire shops almost universally use impact wrenches that put out 400-500 foot-pounds of torque when just 100 might be required. And often, technicians aren’t seating the tire correctly by snugging the nuts first by hand then tightening in a star pattern a couple times around, he said.
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“When you use an impact wrench, you have no control over how tight you tighten those nuts,” he said.
The over-tightening bends the stud while it’s put into tension. While the stud is bent in tension, microfractures can form and develop into a fatigue fracture and a complete failure of that stud.
“Once you break one or two studs, then the remaining ones are unable to hold the wheel on and the assembly basically shakes itself apart.”