The Motor Trade Association wants tougher rules on car tyres, saying the legal minimum for tread of 1.5mm isn't enough.
An image from the Transport Agency showing a tyre tread gauge. Photo: NZTA
Motor Trade Association chief executive Craig Pomare said emergency services changed tyres on their vehicles the tread was down to 3-4mm.
He wants see the minimum tread depth gradually increased for all vehicles, in 0.5mm or 0.25mm increments each year.
Mr Pomare pointed to Transport Agency information, showing how little of a tyre is in contact with wet roads if the tread isn't deep enough, to back up his view.
"At 90 kilometres an hour a vehicle that meets the minimum tread requirement has less than five percent of the tyre tread making contact with the road when there is a bit of moisture. In our minds that is dangerous, so we would want the tread depth increased to help ensure that New Zealanders are safe."
Graphic: NZTA
The Transport Agency diagram shows only a new tyre, with 8mm of tread, has good road contact at 90 km/h in wet weather.
Automobile Association motoring services general manager Stella Stocks said increasing the legally required tread on cars would be too expensive for many motorists.
But she said having longer time gaps between warrants of fitness - of up to three years for some cars - could create a hazard.
"Potentially, the tyres on that vehicle could be unchecked for a period of three years."
Stella Stocks said motorists could have less grip on their tyres than they thought. There were no statistics, but anecdotally, the AA had repeatedly heard about this problem.
Both organisations agreed that for many people, human nature meant they checked their tyres when they had to, rather than repeatedly peering under their car to check on incremental wear and tear.
Mark Eades, Wellington manager for Tony's Tyre Service, sees this problem first hand.
"As I go to a supermarket, I look at car tyres and it is amazing how many are out there whose tyres are bald," he said.
Mr Eades said people who used to have a six-monthly WoF test would check their tyres every six months.
"Since the yearly warrants have come out there seem to be more bald tyres on the road.
"I think the general public have a perception that when they go for a warrant of fitness and they pass, their tyres are going to be fine until the next warrant, and that is generally not the case."
Many owners did not do their own checks and Mr Eade saw many high quality cars with badly worn tyres. "Late model vehicles, a lot of SUVs, all sorts of vehicles."