SINGAPORE — Veteran rugby coach Slemat Rakisan died after he was hit by a runaway tyre on the Kranji Expressway (KJE).

The tyre flew off a prime mover and bounced off the road centre divider before it struck the coach, who was riding a motorcycle.

Delivering her findings from the coroner’s inquiry into his death, State Coroner Kamala Ponnampalam said on Friday (May 10) that the prime mover was “poorly maintained” and the nuts securing its rear left wheels had not been properly tightened.

A senior automotive engineer said that the vehicle was “not in a roadworthy condition” before the accident.

Slemat’s death was ultimately ruled an unfortunate traffic misadventure.

The former national rugby player who was 57 years old when he died on March 16, 2017, previously served as vice-president of the Singapore Rugby Union, as well as president of the Singapore Society of Rugby Union Referees.

The father-of-three was travelling on the KJE towards the Bukit Timah Expressway that afternoon, while the trailer truck was travelling in the opposite direction towards the Pan-Island Expressway.

At the time, the road surface was dry, traffic volume was moderate and visibility was good.

The truck driver, Mr Tan Bee Kiang, testified that he checked the vehicle earlier that morning and found nothing amiss. He had been working for Huationg Inland Transport Service for four years, and had been driving the vehicle for more than a year.

Mr Tan also did not find anything wrong with it while driving, but began to feel it shaking as he drove on an upward slope, somewhere after the Sungei Tengah exit.

As he drove downslope, he saw two tyres from the rear left side roll off the vehicle in opposite directions. One of them struck Slemat, who was riding in the extreme right lane of the four-lane road.

Slemat skidded and was flung off his motorcycle.

Mr Tan managed to steer the prime mover to the road shoulder and safely bring it to a stop.

The police received a call at 3.56pm, and paramedics pronounced Slemat dead at the scene about half an hour later. He had suffered serious injuries consistent with being in a road traffic accident.

On Friday, State Coroner Kamala noted that the prime mover’s rear tyres were last changed two months before the accident because they had gone bald.

Its wheel rims stud holes, for mounting the wheel to the axle, were “badly worn” as well. This, along with the improper tightening of the wheel studs and nuts, caused the rotating left rear wheels to detach from the axle.

The deputy head of Huationg’s workshop said that the prime mover was regularly serviced, and had been due for servicing two weeks after the accident.

An expert who inspected the vehicle said that periodic service of the prime mover is vital, in order to ensure the nuts are properly tightened.

“The vibration of the wheel constantly generates outward force with the tendency to force the wheel nut out from the stud. If the nut tightening is not proper or high enough, the nut would start losing its grip and becoming loose and will eventually be forced out and the wheel would be dislodged from the wheel axle,” the coroner quoted.