Photo/IllutrationMany bolts to attach the tire to the hub are ruptured. The tire came off the vehicle. (Provided by the transport ministry)

  • Photo/Illustraion

Accidents involving tires flying off of heavy-duty trucks and buses have more than quintupled over the past five years, and officials are blaming labor shortages in the freight industry, a transport ministry study found.

Fifty-six such accidents occurred in fiscal 2016 involving trucks with a gross vehicle weight, including maximum loads and body weight, of at least 8 tons and buses with a seating capacity of 30 or more, ministry figures showed.

Some truck tires measure 1 meter across and weigh more than 100 kilograms. They can cause deaths or serious damage if they roll on an expressway and hit humans or objects.

No deaths were reported in the 56 cases, but there have been injuries.

An estimated 80 percent of the accidents were caused by worker error. Bolts and other components ruptured because the bolts had been fastened too loosely or too tightly when the tires were changed, officials said.

Transport ministry officials said the labor shortage in the freight industry could be responsible for the high accident rate.

“Slipshod work may be more common than before,” an official said.

A ministry study showed that more than 70 percent of the 56 accidents occurred within two months after the wheels were changed, for example, to replace winter tires.

The incidents were concentrated in snowy areas, such as the Tohoku, Hokuriku and Shinetsu regions, during winter and spring. A study on the 15-year period through fiscal 2016 showed that most of the tire accidents happened in February.

A 2015 survey conducted in part by the transport ministry showed that 68.8 percent of 1,252 freight companies across Japan were short of drivers.

Drivers now are working on holidays or extra hours of overtime to meet demand.

“Although it is true that no special qualification is required to change tires, those who lack the knowledge and skills may be doing so,” said an official with the transport ministry’s Road Transport Bureau.

Such accidents had been declining since the early 2000s when ruptures and cracks were found in “hubs” linking the front wheels with the axle on a number of heavy-duty trucks manufactured by Mitsubishi Motors Corp.

But the annual numbers started rising again in fiscal 2011, when there were 11 such accidents.

Last year, a spare tire dropped from a truck on an expressway in Okayama Prefecture, causing the deaths of a mother and her daughter.

During the five years through fiscal 2016, there were only four incidents of spare tires falling from large-size vehicles.

Disconnected tires from moving vehicles were much more frequent over the same period.

In fact, the number of disconnected tire accidents in fiscal 2016 surpassed the total of incidents, 52, related to the cracked hubs of Mitsubishi Motors’ vehicles between 1983 and 2004, the year when the automaker announced a recall of the hubs.

In March 2017, a left rear wheel came off a heavy-duty truck in Uji, Kyoto Prefecture, rolled about 400 meters and hit a minicar that was waiting for the lights to change. The minicar’s driver was injured.

In January 2017, a left rear wheel fell off a traveling tractor-trailer in Niigata and hit a minicar on the opposite lane, resulting in injury.

In 2004, a 3-year-old boy was killed when he was directly hit by a tire that came loose from a dump truck in Esashi, Hokkaido. A tire from a trailer hit an oncoming passenger car and killed its driver, also in Hokkaido, in 2000.

Ministry officials said they will call on freight industry officials to use proper tire mounting methods ahead of spring, when winter tires are replaced.

They added that they have had no reports of tires coming loose from general passenger cars.