The briefing identified some heavy, medium and light tankers, and all dual cab utes "may exceed GVM compliance when fully laden with personnel and equipment".

According to the safety alert released by the TFS, Engineering and Fleet Services advised the affected vehicles will operate at a reduced passenger capacity to meet the weight limits.

"EFS has advised these changes will remain permanent with centre consoles fabricated and fitted to seats as a physical barrier during 2023," the briefing read.

"It is the driver's responsibility to ensure occupant levels are not exceeded."

TFS acting-chief officer Bruce Byatt said he was confident the measures would not impact vehicle availability during the upcoming fire season.

"The safety of our firefighters is our highest priority," Mr Byatt said.

"A range of control measures remain in place for the tanker fleet, which includes a reduced number of occupants.

These control measures have been communicated to firefighters."

However, the Tasmanian branch of the United Firefighters Union of Australia raised concerns about the reduced capacity.

"This means that [firefighters] will have to be split up among multiple vehicles and wait longer to get the adequate number of firefighters to an incident in a timely manner," UFU industrial organiser Stephen McCallum said.

"Not only is the community getting a poorer level of service, but you've also got fewer firefighters there at the start of the incident."

In June, the TFS first identified weight issues with 55 light tankers and instigated a review of the light tanker fleet.

Mr Byatt said since an independent engineering review was completed, 22 light tankers have been removed from service - two of which are not being replaced.

Of the remaining 20, nine have been replaced. He said 105 dual cab utes in the TFS fleet had all been tested.

Work is now being undertaken to remove sidebars and steps and new tyres fitted as part of a fleet upgrade.

Mr Byatt said these upgrades would not impact the number of dual cabs in the fleet and would be completed within the next month.

"As we have said before, this situation is not good enough," a Tasmanian government spokesperson said.

"We want our emergency services to have the equipment and vehicles they need and to have it in the right condition for their safety."

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