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Frequently asked questions—vehicle standards and modifications

This page provides answers to the questions most frequently asked by vehicle owners, modifiers and industry about vehicle modifications, standards and inspections. The Department of Transport and Main Roads recommends that you read the information on this page to determine if it answers your question before contacting us.

We will continually review and update the information provided on this page to ensure it is up to date and any new commonly asked questions are included.

Please note: From 10 February 2014, the National Heavy Vehicle Regulator (NHVR) is responsible for the regulation of heavy vehicle standards and modifications in participating jurisdictions.

Queensland, New South Wales, Victoria, South Australia, Tasmania and the Australian Capital Territory are the participating jurisdictions from the commencement of the NHVR.

This page contains information about the most commonly asked questions about heavy vehicle standards and modifications, but if you cannot find the answer to your question, please contact the National Heavy Vehicle Regulator.

Vehicle standards

Codes of practice and certifications

Building vehicles

Light vehicles

Body, windows and restraints

Engine and exhaust

Lights and accessories

Loads and towing

Motorcycles

Tyres, suspension and steering

Heavy vehicles

Body, windows and restraints

Lights and accessories

Loads and towing

Vehicle standards

I have purchased an old vehicle and want to register it, how do I do this?

Before being registered the vehicle must first undergo a safety certificate inspection at an Approved Inspection Station. Once the vehicle has passed the inspection and a Safety Certificate has been issued you may proceed to a Customer Service Centre to apply for registration.

Further details on registering a vehicle.

My vehicle's identification/compliance plate is missing from my vehicle, can I purchase a new one?

Unfortunately, once a vehicle's identification/compliance plate has been lost it cannot be replaced. However, provided acceptable proof can be supplied showing the vehicle had previously been registered in Australia, the vehicle is still able to be considered for re-registration.

Further information regarding missing identification/compliance plates can be found in section 3 of the AIS code of practice.

What is the towing capacity of my light vehicle (gross vehicle mass not exceeding 4500kg)?

A vehicle's towing capacity is set by the vehicle manufacturer. Generally information regarding a vehicle's towing capacity can be found in the owner's handbook or by contacting the vehicle manufacturer.

If the vehicle manufacturer has not specified a maximum towing capacity or it cannot be identified, the following is taken to be the maximum towing capacity:

  • if the trailer is fitted with brakes — one and a half times the unladen mass of the motor vehicle; or
  • if the trailer is not fitted with brakes — the unladen mass of the motor vehicle.

Note: Only trailers with a Gross Trailer Mass (GTM) up to and including 750kg do not require brakes. All trailers with a GTM more than 750kg must be fitted with brakes.

Codes of practice and certifications

Where can I find the light vehicle code of practice for modifications on the website?

There are 2 codes of practice that apply to light vehicles in Queensland.

  • National Code of Practice for Light Vehicle Construction and Modification
  • Queensland Code of Practice: Vehicle Modifications (light vehicle section)

Both are available from the light vehicle modifications section of our website.

Where can I find the heavy vehicle code of practice for modifications?

From 10 February 2014, the National Heavy Vehicle Regulator (NHVR) took over responsibility for regulating heavy vehicle modifications in participating jurisdictions (Queensland, New South Wales, Victoria, South Australia, Tasmania and the Australian Capital Territory).

From this date, the code of practice for heavy vehicle modifications is the NHVR's Code of Practice for the Approval of Heavy Vehicle Modifications. This code, available from the NHVR website, explains how modifications will be managed by the NHVR and recognises a number of established modification standards, such as:

Where do I find a list of Approved Person and Approved Person Engineers that carry out light and heavy vehicle modifications?

For contact details of Approved Persons please contact the Department of Transport and Main Roads by phone on 13 23 80.

Will I still be able to have modifications to my heavy vehicle certified by an Approved Person and have a modification plate affixed?

Yes, the National Heavy Vehicle Regulator's system for approving modifications is almost identical to the previous system that operated in Queensland. This means that any modification that could have previously been assessed and certified by an Approved Person under the National Code of Practice – Heavy Vehicle Modifications (Vehicle Standards Bulletin 6) can still be assessed and certified by an Approved Person.

I want to remove my truck body and fit a fifth wheel coupling, do I need these modifications approved?

These modifications can be performed provided they are certified by an Approved Person.

The Approved Person will utilise the J and P sections of National Code of Practice – Heavy Vehicle Modifications (Vehicle Standards Bulletin 6) to ensure the modifications have been performed correctly.

Further information regarding body and tow coupling modifications can be found in the J section and P section of Vehicle Standards Bulletin 6.

Building vehicles

I want to build my own car, where do I find the information on the web to help me to do this?

Information regarding the build process and construction standards for Individually Constructed Vehicles (ICVs) can be found in:

I want to build a street rod (hot rod), who do I talk to?

In Queensland, the Queensland Street Rod Federation (QSRF) administers the street rod scheme. Information on building street rods in Queensland can be found on the QSRF website.

I want to build a light trailer (aggregate trailer mass of not more than 4500kg), where on the web would I find the government standards, and are they state-by-state standards?

The standards relating to building a light trailer are provided by the Commonwealth Department of Infrastructure and Regional Development. These standards are used by all States and Territories and are available from the Commonwealth Department's website.

Light vehicles

Body, windows and restraints

I want to put a darker than T35 window tint on the side window behind the driver seat, can I do this?

No, tint applied to any side or rear window of a light vehicle (vehicle with a gross vehicle mass not more than 4,500kg) must not have a light transmittance of less than 35% (T35). This includes the combination of any applied tint and factory tinted glass.

However, please be aware that the Australian Design Rules now allow privacy glass to be fitted rearwards of the driver's vision. Privacy glass has no minimum light transmittance and is often darker than T35 tint.

Privacy glass incorporates tinted film within the glazing and does not involve an applied tint. All applied tint must meet the above requirements (for example, must not be darker than T35) and not the requirements set out for privacy glass in the Australian Design Rules.

Please note: Tinting may be fitted to the upper portion of a windscreen of a motor vehicle. The tinting must not extend lower than a horizontal line connecting the uppermost points of the arcs swept by the vehicle manufacturer’s original wiper blades or upper 10 percent of the windscreen, whichever is the lesser. The tinting may be of any shade but must not have a reflectance of more than 10 percent.

For further information about window tinting please refer to the Minor Modifications publication and the LZ section of the National Code of Practice for Light Vehicle Construction and Modification.

For the tinting requirements that apply to heavy vehicles (vehicles with a gross vehicle mass of more than 4,500kg), please contact the National Heavy Vehicle Regulator.

I want to change the cabin of my 4WD as it has rusted out. Can I replace it with another one?

If the replacement cabin is an identical make, model and variant to the original vehicle, the replacement cabin is considered a repair and does not require approval by an Approved Person. However, the vehicle will be required to have a surrogate Vehicle Identification Number (VIN) issued to link the existing vehicle's identification number with the replacement cabin's identification number. To apply for a surrogate VIN please contact your local Queensland Police Station.

If the replacement cabin is a different make, model or variant to the original vehicle, the new cabin is considered a modification which must by certified by an Approved Person. Additionally, a surrogate VIN will be required.

For further information about cabin modifications please refer to the LH section of the National Code of Practice for Light Vehicle Construction and Modification.

Am I permitted to fit a bonnet scoop to my vehicle?

A vehicle may be fitted with a bonnet scoop provided it meets certain safety standards. These standards have been developed to ensure the bonnet scoop does not:

  • interfere with the field of view of the driver
  • increase the risk of injury to vulnerable road users in the event of a collision
  • reduce the structural integrity of the vehicle's bonnet

The standards relevant to bonnet scoops can be found in the Minor Modifications publication.

I want to fit child restraints to my vehicle, can I see any mechanic and have this work done?

The certification of child restrains will need to be approved by a Department of Transport Approved Person under the LK6 section of the National Code of Practice for Light Vehicle Construction and Modification.

I want to convert my bus to a motorhome, where can I find information that explains what standards I need to meet?

The standards for motorhome/campervan conversions for light vehicles can be found in the National Code of Practice for Light Vehicle Construction and Modification under the LH11 code.

The requirements for heavy vehicle motorhomes can be found in Commonwealth Administration Circular 0-4-12 Certification of Campervans and Motorhomes.

I am looking at purchasing a caravan/motorhome which only has an access door on the right hand side, is this permitted?

No, all caravans and motorhomes must have at least an outward opening or sliding access door located on the left hand side or rear of the vehicle. The door must provide a space through which an average sized person can easily pass through. Additionally, no external fittings (i.e ladders) shall be required to access the door.

Engine and exhaust

I want to replace my vehicle’s engine. The engine I want to fit is an original manufacturer’s option for my vehicle, can I do this and do I need a modification plate?

Replacement engines that are offered by the manufacturer as an optional engine for that model of vehicle may be fitted without specific approval or the fitment of a modification plate. For such conversions, all components, including suspension and brakes, must be identical to those of a vehicle originally produced with the optional engine. No modification plate is required to be fitted.

For further information about replacement engines, please refer to the Minor Modifications publication and the LA section of the National Code of Practice for Light Vehicle Construction and Modification.

I want to fit a POD filter to my vehicle. Can I do this? And do I need a mod plate?

A replacement air filter (including a pod filter) may be fitted to a vehicle without specific approval by the Department of Transport and Main Roads and without having a modification plate fitted, provided:

  • it is securely attached to the vehicle
  • it does not cause an increase in noise from the air intake system (to resolve this issue the air filter element may have to be effectively encased or boxed-in)
  • the vehicle's gaseous emissions are not adversely affected

Please note: It is also important to be aware that some types of sensors give false readings when oil soaked air filters are used. When oil soaked air filters are used, confirmation should be sought from the manufacturer about the effect on the exhaust emissions. Additionally, air filters should be flame retardant.

Further information regarding replacement air filter requirements can be found in the Minor Modifications publication.

I want to fit a blow-off valve to my turbo vehicle, do I need a modification plate?

Fitting a blow-off valve is considered a minor modification and does not require approval. When fitting a blow-off valve, it must be vented back into the vehicle's induction system. Blow-off valves that vent directly to the atmosphere must not be fitted.

I want to fit Nitrous Oxide to my vehicle. Can I do this? If not, can I just simply remove the bottle and leave the lines in and fit the bottle as needed?

The fitting of nitrous oxide injection systems is not permitted under any circumstances. This includes a partial installation or a disconnectable nitrous oxide system fitted to a vehicle.

I want to fit an aftermarket fuel tank to my 4WD vehicle, do I need a modification plate?

Replacement and additional fuel tanks may be fitted to a vehicle provided the modification is certified to the LM section of the National Code of Practice for Light Vehicle Construction and Modification by an Approved Person.

Can I fit a power chip to my standard vehicle? Do I need a modification plate?

Power chips, aftermarket (not installed by the original vehicle manufacturer) or re-mapped engine management computers are permitted without specific approval, provided the vehicle continues to comply with the emission requirements applicable at the time of the vehicle's manufacture. However, if any engine modification (or combination of engine modifications) increases the engine's original power output by more than 20%, the modification requires certification by an Approved Person.

Further information relating to engine modifications can be found in the Minor Modifications publication and the LA section of the National Code of Practice for Light Vehicle Construction and Modification.

Can I fit extractors to my late model vehicle? Do I need a modification plate?

Yes extractors can be fitted to a vehicle as long as the emission and noise levels continue to meet the Australian Design Rules. However, if any engine modification (or combination of engine modifications) increases the engine's original power output by more than 20%, the modification requires certification by an Approved Person.

Further information relating to engine modifications can be found in the Minor Modifications publication and the LA section of the National Code of Practice for Light Vehicle Construction and Modification.

Lights and accessories

I want to fit spot lights to my vehicle, do I have to fit them in pairs or can I just fit one?

Additional driving lamps (including LED light bars) may be fitted to a vehicle provided they meet the following requirements:

  • The lamps should, as far as is possible, be installed symmetrically in pairs to the front of the vehicle
  • If lamps are not fitted as pairs (e.g. one, three etc), they must be fitted to the front of the vehicle, symmetrically about the centre
  • The lamp/s must be installed in a way that ensures the light produced does not cause the driver of the vehicle discomfort either directly or by reflection
  • The lamp/s must only come on when the main-beam (high beam) headlamps are used, and must automatically turn off when the main-beam headlamps are turned off

Further information on additional driving lamps can be found in Fitment and use of driving lamps including light emitting diode (LED) light bars on vehiclesVehicle Standards Information G15 .

Can I fit fishing rod holders to my vehicle?

A vehicle can be fitted with a fishing rod holder provided it complies with the following requirements:

  • Must only be attached to the left side of the vehicle
  • Must be designed to carry no more than four fishing rods
  • Rods, hooks and sinkers must be properly secured
  • Vehicle lighting must not be obstructed by rods or the holder
  • The rod holder must be either removed or retracted behind the profile of the bull bar when not in use

For further information about vehicle protrusions, please refer to the Minor Modifications publication.

I have 2 UHF radios, can I fit the aerials to the bull bar and do I need a modification plate?

A vehicle can be fitted with long range antennas without specific approval, provided they meet the following requirements:

  • Forward mounting of an antenna is permitted only when it is impossible or impractical to install the antenna to the rear of the vehicle.
  • The installation must be attached as low as is practical to ensure the large diameter section of the antenna projects above the bonnet line as little as possible.
  • Only one long range antenna (large diameter base) may be fitted to the front of a vehicle and must be fitted to the left side (maximum diameter permitted 75mm).
  • All sharp edges or protrusions which could cause injury to anyone making contact with the device must be removed or rounded.

For further information about vehicle protrusions please refer the Minor Modifications publication.

Is it possible to fit additional gauges to the driver’s side A pillar of my vehicle?

Additional internal or external gauges may be fitted to a vehicle without specific approval provided they do not:

  • interfere with the field of view of the driver
  • produce glare to the driver
  • pose a risk of pressurised fluids spraying (eg, fluids from an oil line, coolant line, etc) onto the windscreen or vehicle occupants
  • increase the risk of injury to a vehicle occupant or vulnerable road users in the event of a collision
  • encroach upon the deployment area of any of the vehicle's Supplementary Restraint Systems (Air bags, seatbelts, head restraints, etc)

Can I fit a GPS unit to the windscreen of my vehicle?

A GPS unit may be fitted to the front windscreen of a vehicle provided it does not affect the driver's field of view. It is also important to ensure the unit is securely attached and is not mounted in a position which could interfere with the deployment of an airbag.

For further information about fitting visual display units, including GPSs, please refer to the Minor Modifications publication or Vehicle Standards Instruction G3 Fitting of visual display units.

Can I replace my vehicle’s headlight with High Intensity Discharge (HID) lamps?

Retro-fitting High Intensity Gas-Discharge (HID) headlight assemblies to vehicles not originally offered with the technology is generally not permissible as they do not comply with the Australian Design Rules in the following ways:

  • No headlight self-levelling device is fitted
  • No self-cleaning function is fitted
  • The design of the headlamp reflector is not compatible with the bulb (the light is not focused correctly)

Can I put my vehicle’s battery in the boot and, if so, will I need to use a battery box?

It is permissible to relocate a vehicle's battery, provided it meets the following requirements:

  • The battery is adequately restrained
  • Cables are shielded to prevent damage
  • Rubber grommets must be fitted where a cable passes through a hole in body panels and/or chassis sections
  • Battery cables are securely mounted to the vehicle at a maximum spacing of 600mm
  • Battery cables are adequate to carry the electrical system's maximum load
  • The battery must be fully enclosed and the enclosure vented to outside the vehicle (unless a special kind of battery e.g, a sealed gel cell is used).

At what point do I need side running lights on my caravan?

Side marker lights are required on a caravan that is over 2100mm wide or 7500mm long

Further information regarding trailer lights can be found in Vehicle Standards Bulletin 1 - National Code of Practice: Building Small Trailers.

Can I put a green flashing light on my vehicle?

Green flashing lights can only be fitted to types of vehicles that have been authorised by the Department of Transport and Main Roads. The types of vehicles currently approved include:

  • Animal management vehicles
  • Fire management vehicles.

For further information about the types of vehicles that can be fitted with green flashing lights, please refer to the Guideline for the installation of auxiliary flashing warning lamps to animal management and other specified vehicles (Form 27).

General information about the fitting of additional lighting to vehicles can be found in the Minor Modifications publication.

Loads and towing

My car and caravan combination is longer than 7.5m, can I fit a "do not overtake" sign to the rear of my vehicle and where would I find information on this?

A vehicle that is 7.5m long or longer may display a "do not overtake turning vehicle" sign. These signs are known as rear marking plates and further information is available in Vehicle Standards Bulletin 12 – Rear marking plates.

I want to fit a fifth wheel coupling to a light vehicle, does this need certification?

The fitment of a tow coupling on a light vehicle is not considered a modification that requires certification by an Approved Person. However, the installation must be in accordance with the tow coupling manufacture's installation instructions or, if not available, the P2 code found in the National Code of Practice – Heavy Vehicle Modifications (VSB6) should be used for guidance.

What is the difference between a trailer’s tare weight, gross trailer mass and aggregate trailer mass?

Aggregate Trailer Mass (ATM)

ATM is the total mass of the trailer when carrying the maximum load recommended by the manufacturer. This includes mass imposed onto the towing vehicle when the combination vehicle is resting on a horizontal supporting plane.

Gross Trailer Mass (GTM)

GTM is the mass transmitted to the ground by the tyres of the trailer when coupled to a towing vehicle and carrying the maximum load recommended by the manufacturer or importer, approximately uniformly distributed over the load bearing area.

Tare Mass

Tare Mass is the total mass of the trailer when not carrying any load, but when ready for service, unoccupied (if relevant) and with all fluid reservoirs (if fitted) filled to nominal capacity except for fuel, which shall be 10 litres only, and with all standard equipment and any options fitted. This includes any mass imposed onto the drawing vehicle when the combination vehicle is resting on a horizontal supporting plane. (Fluid reservoirs do not include water tanks and waste water tanks fitted to caravans).

Motorcycles

I want to fit a side car to my bike, where can I find some information that may help?

Sidecars which bolt directly to the motorbike's frame without the need for any modifications to the motorbike are considered acceptable under self- certification. However, sidecars which require the motorbike to be modified (i.e. welding to the frame, etc) must be approved by the Department of Transport and Main Roads. Before modifying your motorbike you should engage the services of an Approved Person Engineer who can provide technical advice and assist with your application.

For further information about sidecar requirements, please refer to the Minor Modifications publication.

Tyres, suspension and steering

Can I fit different tyres and rims to my vehicle than those mentioned on my vehicle’s tyre placard?

Yes, you may fit a tyre/rim combination with a different width and/or overall diameter provided it meets certain requirements. The amount the width and diameter can increase/decrease largely depends on the type of vehicle (e.g. passenger vehicle, 4WD) in question.

For further information about the limits for increasing or decreasing width and/or overall diameter, please refer to the Minor Modifications publication and the LS section of the National Code of Practice for Light Vehicle Construction and Modification.

Can I lower my vehicle’s ride height?

A vehicle's suspension may be lowered provided it maintains a ground clearance of at least 100mm and 2/3 original suspension travel (in both directions).

Please note: A pre-1969 vehicle is permitted to have a ground clearance of less than 100mm if produced in this configuration by the original vehicle manufacturer.

For further information about the limits and requirements for lowering a vehicle's ride height, please refer to the Minor Modifications publication and the LS section of the National Code of Practice for Light Vehicle Construction and Modification.

Can I raise my vehicle’s ride height?

A vehicle's ride height can be increased in a number of ways. These include:

  • Tyre diameter increase
  • Raising a vehicle's suspension
  • Body blocks

The limit a vehicle's ride height can be increased is dependant on which combination of the above method(s) are used. Each of the above vehicle lift methods have a maximum allowable increase they can achieve (maximum suspension lift 50mm, maximum tyre diameter increase 50mm, maximum body block lift 50mm). The maximum total combined lift of the vehicle cannot exceed 125mm.

Please be aware the maximum allowable limits specified above are not applicable to all vehicle types.

For further information about the limits and requirements for raising a vehicle's ride height, please refer to the Minor Modifications publication and the LS section of the National Code of Practice for Light Vehicle Construction and Modification.

I would like to put low profile tyres and larger diameter rims on my vehicle, is this possible?

Yes, a vehicle's tyre profile may be changed provided the new tyre's overall diameter, speed rating and load rating comply with the relevant requirements. To maintain the correct overall diameter low profile tyres are normally fitted in combination with rims of a larger diameter than standard.

For further information about the limits for fitting alternate tyres and rims, please refer to the Minor Modifications publication and the LS section of the National Code of Practice for Light Vehicle Construction and Modification.

I have been told I can put 50mm large diameter tyres on my 4WD, they do this in other states and territories, is this permitted in Queensland?

Yes, the following types of vehicles can have their tyre diameter increased by up to 50mm or reduced by no more than 26mm from any tyre diameter designated by the vehicle manufacturer for that vehicle:

  • 4WD passenger vehicles specifically designed for off-road use (typically MC ADR category), or
  • 4WD goods vehicles and their 2WD equivalents if the chassis and running gear are essentially the same as the 4WD versions (N ADR category)

Please note: All wheel drive(AWD) vehicles, commonly known as soft roaders,are not to be considered as one of the above mentioned vehicles.

Further information about fitting alternate tyres and rims, please refer to the Minor Modifications publication and the LS section of the National Code of Practice for Light Vehicle Construction and Modification.

I want to lower the speed rating of my tyres from a "V" to an "N" rated tyre, can I do this?

The speed rating of a vehicle's tyres can change, provided they meet at least the following:

  • for an off-road passenger vehicle – 140km/h
  • for another car (sedan, station wagon etc.) with up to nine adult seating positions or a car derivative – 180km/h
  • for another motor vehicle – 120km/h
  • Or the vehicle's top speed, if lower than the above mentioned speeds.

For further information about tyre speed ratings, please refer to the Minor Modifications publication and the LS section of the National Code of Practice for Light Vehicle Construction and Modification.

I want to reverse the axle on my caravan (change from spring under to spring over or vice versa), can I do this?

A caravan/trailer axle can be changed from spring under to spring over (or vice versa) only if it was provided as an option by the original manufacturer. For such conversions, all components, including suspension and brakes, must be identical to those of a caravan/trailer originally produced with the alternative axle position.

I want to lower the GVM of my ute so I can put passenger car tyres on it, can I do this?

No, a light vehicle's Gross Vehicle Mass cannot be modified from the manufacturer's specified value.

Is it possible to replace my vehicle’s original steering wheel with an aftermarket steering wheel?

It is acceptable to replace a vehicle's steering wheel without specific approval, provided the replacement steering wheel does not affect compliance with ADR 10 - Steering Column (vehicles manufactured after 1970), ADR 21 – Instrument Panel, ADR42 – General Safety Requirements and ADR 69 – Full Frontal Impact Occupant Protection (vehicles manufactured after June 1995). Unless a steering wheel is marked, or has accompanying information or documentation that shows it has been tested to the appropriate ADRs, it must not be used as a replacement. In addition, for vehicles required to comply with ADR 69, the steering wheel assembly must be identical to one fitted as an option to the same model by the vehicle manufacturer, or alternatively, a steering wheel that has been certified by the replacement wheel manufacturer as a complying wheel for the specific make and model may be used.

Replacement steering wheels should not be less than 330mm in diameter. If the original steering wheel was designed with a recessed or padded hub, the replacement wheel should be of a similar design.

Please note: Removable/quick release steering wheels must not be fitted.

Can I fit different brand tyres to the same axle of my vehicle?

While a vehicle can be fitted with different tyres (eg, brand, tread pattern), the tyre construction (eg, crossply, steel radials, textile radials, etc) must not differ.

Please note: the Department of Transport and Main Roads does not recommended fitting tyres with different tread patterns on a vehicle's axle.

Heavy vehicles

Body, windows and restraints

I want to convert my bus to a motorhome, where can I find information that explains what standards I need to meet?

The standards for motorhome/campervan conversions for light vehicles can be found in the National Code of Practice for Light Vehicle Construction and Modification under the LH11 code.

The requirements for heavy vehicle motorhomes can be found in Commonwealth Administration Circular 0-4-12 Certification of Campervans and Motorhomes.

I am looking at purchasing a caravan/motorhome which only has an access door on the right hand side, is this permitted?

No, all caravans and motorhomes must have at least an outward opening or sliding access door located on the left hand side or rear of the vehicle. The door must provide a space through which an average sized person can easily pass through. Additionally, no external fittings (i.e ladders) shall be required to access the door.

Lights and accessories

Can I put a green flashing light on my vehicle?

Green flashing lights can only be fitted to types of vehicles that have been authorised by the Department of Transport and Main Roads. The types of vehicles currently approved include:

  • Animal management vehicles
  • Fire management vehicles.

For further information about the types of vehicles that can be fitted with green flashing lights, please refer to the Guideline for the installation of auxiliary flashing warning lamps to animal management and other specified vehicles (Form 27).

General information about the fitting of additional lighting to vehicles can be found in the Minor Modifications publication.

Loads and towing

What is the difference between a trailer’s tare weight, gross trailer mass and aggregate trailer mass?

Aggregate Trailer Mass (ATM)

ATM is the total mass of the trailer when carrying the maximum load recommended by the manufacturer. This includes mass imposed onto the towing vehicle when the combination vehicle is resting on a horizontal supporting plane.

Gross Trailer Mass (GTM)

GTM is the mass transmitted to the ground by the tyres of the trailer when coupled to a towing vehicle and carrying the maximum load recommended by the manufacturer or importer, approximately uniformly distributed over the load bearing area.

Tare Mass

Tare Mass is the total mass of the trailer when not carrying any load, but when ready for service, unoccupied (if relevant) and with all fluid reservoirs (if fitted) filled to nominal capacity except for fuel, which shall be 10 litres only, and with all standard equipment and any options fitted. This includes any mass imposed onto the drawing vehicle when the combination vehicle is resting on a horizontal supporting plane. (Fluid reservoirs do not include water tanks and waste water tanks fitted to caravans).

Last updated
20 September 2016