It also had a slick front tyre which would not have allowed it to pass a warrant of fitness test.
Although this was not a factor in the accident and could have increased the grip available given the dry road conditions at the time, it was illegal to use on a registered motorcycle.
Mr Tidmarsh said Mr Brown would have had a reaction time of around a second when he first saw the police car about 120 metres away on Waerenga Rd.
Had he been travelling at the speed limit of 100km/h he could have stopped "no problem" but Mr Brown was travelling between 114km/h and 142km/h.
At 114km/h Mr Brown would have needed 157m to stop at 50 per cent braking efficiency.
Lenihan did not give evidence but an independent crash analyst, Graham Williams said his tests showed Mr Brown was more likely to have been travelling at an average speed of 149km/h before the collision.
"The crash was inevitable, so were the injuries, they were inevitable," he said.
"He could not have stopped."
In his closing submission, Lenihan's lawyer Mike Curran said he had had a momentary lapse of judgment and made a miscalculation in terms of the width of the road when attempting his u-turn.
"He made a decision to turn and it had tragic consequences but only because of the actions of the driver of the motorcycle and the speed he was doing."
But Crown prosecutor Philip Crayton said Lenihan's actions were not those of a "reasonable and prudent" driver.
Had Lenihan not performed the manoeuvre there would have been no obstruction and no accident.
"That manoeuvre changed from effectively occupying one side of the road to obstructing the highway."
Mr Crayton said an intersection 150m from the crash site would have provided Lenihan with an opportunity to complete a quick and safe turn.
Lenihan was performing the u-turn to chase Carl Jackson, who was Mr Brown's best friend and was clocked driving at more than 150km/h.
Judge Lance Moore has reserved his decision until later today.
