It may be difficult to estimate how often a wheel falls off a moving eighteen-wheeler. The Commercial Vehicle Safety Alliance says that truckers may not even know that a wheel has fallen off for a period of time. Incidents often go unreported.
The issue was brought into the limelight in the early 1990s after a series of fatal accidents involving wheel separations prompted the National Transportation Safety Board to look into the issue, the CVSA says. But, the problem continues to occur today. The alliance says that it could happen several times a day across the country.
In the aftermath of the rash of fatal accidents in the early 1990s, the NTSB concluded that faulty maintenance and-or improper tightening of nuts on the wheels were the biggest problems in causing wheel separation. The danger with this type of issue is that the wheel can be launched into traffic on the open road, presenting a hazard for anyone in the vicinity.
A loose wheel is being blamed for the death of a Missouri man in a freak accident in Oklahoma. The Missouri man himself had a tire problem and pulled over to change a flat along Interstate 44. As he was attending to his flat tire, a semi-truck came bounding down the eastbound lanes of the interstate. As the big rig neared the Springfield, Missouri, man's stopped vehicle, the trailer lost two wheels.
The rear duals separated from the trailer. One of the wheels bounded down the road, coming to a stop against the barrier in the center median. But, the other wheel struck the Springfield, Missouri, man as he worked on his disabled vehicle. The blow proved to be fatal.
Source: Four States Homepage, "Missouri Man Dead After Semi-Truck Tire Malfunction," Kate Inman, Feb. 7, 2014