The NRMA has raised safety concerns about a proposed trial of larger three-trailer trucks on the Hume Highway between Sydney and Melbourne.
The New South Wales Government is considering a trial of B-triple trucks, which are about 36 metres long - 10 metres longer than the B-doubles that currently ply the Hume Highway.
The state's Roads Minister Duncan Gay says a trial would not begin until 2014 at the earliest.
This is due to the construction of a dual carriageway along the entire length of the highway, which is due to be completed next year.
It is being considered as part of a national plan to increase the use of B-triples, which are already used in western New South Wales and other states.
However, NRMA spokesman Peter Khoury says there have already been serious truck safety issues on the highway, and the heavier B-triples will do more damage in a crash.
"The Hume Highway has already been upgraded and those crashes occurred on the upgraded sections of the Hume Highway," he said.
"It's important to remember that B-doubles can actually go straight through crash barriers, so there is an obvious safety risk there.
"The trucks that are on the Hume Highway already are causing safety issues."
But proponents say bigger trucks mean fewer trucks.
Australian Trucking Association spokesman Bill McKinley says the large trucks will never be seen on suburban streets.
"B-triples are what you call long-haul combinations. They're a combination you use to deliver freight from a distribution centre on the outskirts of Melbourne to a distribution centre on the outskirts of Sydney," he said.
"The combination is then broken up and the individual parts then go to their destination."
But the proposal comes in the same year as road authorities cracked down on rogue trucking companies, in response to .
Authorities subsequently found widespread issues within the trucking industry, including trucks found to have tampered speed limiters.
Mr Gay says the industry is now being more stringently policed.
"Currently, nearly half the state operates B-triples. All of the western division of NSW operates B-triples and this mania about monster trucks in not the case," he said.
"These are the safest trucks on our roads."
Victoria's Acting Premier Peter Ryan rejected safety concerns about introducing triple-trailer trucks on the Hume Highway.
Mr Ryan says the Victorian government will closely watch the results of the trial, but he does not believe the trucks are inherently dangerous.
"I think the issue is around driver behaviour as opposed to the safety of the vehicle per se," he said.
"And I think issues around driver behaviour are just as pertinent whether they're driving a golf cart or whether you're driving a B-triple.
"We in Victoria will watch this with interest and we will see what eventuates.
"I know that the Transport Minister and the transport industry are always in conversations about the means by which they can better achieve efficiencies of movement."