If truck drivers want to benefit from improved efficiencies they should be forced to improve the safety of their vehicles as a condition, the Automobile Association (AA) says.
The government wants to increase the size of trucks on the roads.
The proposals include raising the gross weight on eight-axle vehicles from 44 to 45 tonnes, and making it easier for trucks with more axles to carry up to 50 tonnes of weight.
Car transporters will be allowed to increase from 36 to 38 tonnes all up. Trucks will also be allowed to be slightly higher and wider.
The aim is to boost efficiency in the trucking sector.
Mark Stockdale from AA said that was a good thing, but truck drivers should have to do something in return for getting an easier life.
"That should go hand in hand with requiring those vehicles to have minimum safety features like ABS brakes, electronic brake distribution systems and under-run barriers on all new trucks and trailers," he said.
Under-run barriers are designed to stop a car from sliding underneath a truck during a crash.
Mr Stockdale said they were not expensive.
"The AA would like underarm barriers to be made mandatory in order for truck operators to be able to operate with higher weights," he said.
But Chief Executive of the Road Transport Forum said underrun bars were an unproven safety system and could cause problems as well as solving them, such as deflecting people or cars into oncoming traffic.
And he said safety would be improved by the proposed changes, even though their main focus was efficiency.
"The whole country benefits from having a more productive and efficient transport sector," he said.
"The other aspect is that modern trucks are a lot safer. The newer heavier trucks carting the bigger heavier loads have much improved braking systems, they have the latest technology, this is all part of those reforms."
Associate Minister of Transport, Craig Foss, said the AA could put its views on safety when it makes its response to the draft proposals.
And he said the proposals would make roads safer.
"If there are less journeys on the road by definition they would be slightly less dangerous," he said.
"Freight across New Zealand's roads is going to increase by 78 percent in the next 25 years, so having larger trucks would mean fewer journeys and would make out roads safer."
Mr Foss said the current rules had been in place for over 13 years and undergone 11 amendments, but there had been no comprehensive overall review.
While they generally worked well, Mr Foss said they needed a thorough examination.
The proposal is now out for public discussion.