The Caravan DatabaseA GVM upgrade raises the legal weight your tow vehicle can carry. It does not raise what the vehicle can tow, and in most cases it does not raise the combined weight of vehicle and caravan either. Those two facts explain most of the arguments about GVM upgrades in caravanning groups, so this guide starts with them, then covers the rules, the limits and who supplies the kits.
Rules differ between states and change over time. Every regulatory statement below links to the government source it comes from, as published at 1 October 2026. Check the current page for your state before you spend money.
The Weights That Matter
- Gross Vehicle Mass (GVM): the most the vehicle is allowed to weigh fully loaded. When you are towing, that includes the weight the caravan puts on the tow ball.
- Gross Combination Mass (GCM): the most the vehicle and trailer are allowed to weigh together.
- Braked towing capacity: the heaviest braked trailer the vehicle is rated to tow.
- Axle load limits: the most each axle is allowed to carry.
- Tow ball download: the weight the caravan presses down on the tow bar. It counts towards the vehicle's GVM and its rear axle load.
Western Australia's transport department publishes plain definitions of all of these, taken from the Australian Design Rules.
A typical problem looks like this: a dual-cab ute with a canopy, drawers, a bull bar, a second battery, two adults and a full tank is close to its GVM before the caravan is hitched. A caravan puts roughly 10 per cent of its loaded weight on the tow ball, so a 3,000kg van adds about 300kg, and the vehicle is over. Our payload calculator and rig loading simulator show where your own setup sits.
What a GVM Upgrade Changes, and What It Doesn't
A GVM upgrade is an engineered package, usually heavier springs and matched shock absorbers and sometimes other parts, that has been tested and approved so the vehicle can legally carry more.
It raises: the GVM, and with it the payload. Axle limits rise only if the kit has been separately assessed and approved for higher axle loads. Queensland's modification code for GVM re-rating (LS11) requires the axle loading to be assessed at the new GVM, and some kits leave an axle at its factory rating.
It does not raise:
- Braked towing capacity. A GVM upgrade is not a towing upgrade.
- GCM. Western Australia says so directly: increasing GVM does not automatically increase GCM, and "upgrading the GVM of a vehicle without upgrading the GCM will reduce the weight of trailer that can be towed when the vehicle is loaded to its new maximum mass". The Northern Territory's GVM bulletin says the same.
- The tow bar's rating, or the tyre and wheel load ratings.
The Trade-Off Nobody Mentions
Because GCM stays the same, every extra kilogram you load into the vehicle comes off what you can tow. Take a wagon with a 3,280kg GVM, a 3,500kg towing capacity and a 6,750kg GCM. Upgrade the GVM to 3,800kg and load the vehicle to that figure, and the heaviest caravan the GCM allows is 6,750 minus 3,800: 2,950kg, not 3,500kg.
A GVM upgrade fixes an overloaded vehicle. It can leave you with a combination that is still over its GCM. Work out both numbers before you buy, and use the tow-match checker to test a specific vehicle and van.
The Two Legal Pathways
Before First Registration: One Federal Approval
A new vehicle can be upgraded before it is first registered, under the federal second stage of manufacture scheme. The kit maker holds a vehicle type approval for that kit on that model, fits it (or has an authorised installer fit it), and records the upgraded vehicle on the national Register of Approved Vehicles.
Two things to know:
- The approval belongs to the kit maker, and it covers that exact combination of parts on that exact model.
- Since July 2021 there is no federal compliance plate for new approvals. The vehicle is identified through the register and its secure vehicle identification marking. Many suppliers' websites still talk about a compliance plate.
Suppliers describe a pre-registration upgrade as recognised in every state. South Australia, for example, requires no action from its vehicle standards team when a vehicle is re-rated this way before first registration. Western Australia's guidance refers to its department issuing a modification permit in each case, so confirm what applies there.
After Registration: State by State
Once a vehicle has been registered, the federal scheme no longer applies. The upgrade is a vehicle modification under state or territory law, and each has its own process:
| State | Who certifies | Recognises another state's in-service upgrade? |
|---|---|---|
| NSW | A VSCCS licensed certifier; the certificate is then lodged with Service NSW | No. Interstate certificates "are not recognised in NSW" |
| Victoria | A VASS signatory, who issues a certificate and a blue modification plate | Not stated |
| Queensland | An Approved Person, under modification codes LS11 and LS15 | Queensland warns its certifications "may not be recognised in another state" |
| Western Australia | An approved installer or automotive consultant; the department issues a modification permit | Recognised while travelling. A vehicle moving to WA must be assessed there |
| South Australia | A Light Vehicle Engineering Signatory; the department issues a Certificate of Exemption | Not stated |
| Tasmania | An Approved Vehicle Certifier | Yes, where a legitimate modification plate is fitted |
| Northern Territory | An engineering signatory and a Transport Inspector; a certificate must be carried in the vehicle | The NT warns its approvals may not be accepted elsewhere |
| ACT | A recognised engineering signatory, including those approved in other states | Accepts other states' signatories |
Three practical points follow from that table:
- An in-service upgrade may not travel with the vehicle. If you might move interstate or sell the vehicle interstate, a pre-registration upgrade avoids the question.
- You usually have to update the registration yourself. NSW says the record is not updated automatically when the certificate is issued, and Queensland says the same.
- Not every vehicle is eligible after registration. Queensland and Western Australia limit in-service GVM upgrades to vehicles built on a ladder chassis. Vehicles with a combined body and frame are excluded.
Can You Upgrade GCM or Towing Capacity?
This is where the states disagree most.
- Federal. The department does not assess, approve or endorse the GCM of any light vehicle. A second stage manufacturer can raise the braked towing figure above the original only with test evidence of compliance with the design rules.
- Queensland allows in-service GCM and braked towing capacity re-rating under code LS16, with a full design package and testing.
- Western Australia allows GCM re-rating only with its own approval, never a braked towing capacity increase, and does not accept a re-rated GCM shown on another jurisdiction's plate, including one fitted before registration.
- Northern Territory and Tasmania do not allow towing capacity above the original manufacturer's figure.
- South Australia allows braked towing capacity re-rating case by case through an engineering signatory.
- NSW treats GCM re-rating as a significant modification that needs certification.
If a supplier offers a GCM or towing capacity upgrade "legal in every state", ask how it is treated in the state where the vehicle is registered and in any state you may move to.
Limits That Catch Owners Out
- The 4.5 tonne line. A vehicle with a GVM above 4.5 tonnes is a heavy vehicle. In NSW a car licence covers vehicles up to 4.5 tonnes GVM, and South Australia says a vehicle re-rated above 4,500kg must be registered and insured as a heavy vehicle and driven on a heavy vehicle licence. Kits sold for large wagons and utes stop short of that line.
- Tyres and wheels. They must be rated for the new GVM and axle loads, and the approval is tied to particular tyre and rim sizes. Changing them later can undo the approval.
- The approved parts must stay on. Western Australia says fitting different components from those approved "will invalidate the GVM upgrade approval", and the original manufacturer's figures apply again.
- Vehicle category. Some upgrades move the vehicle into a different design rule category. One supplier notes that its LandCruiser 300 kit changes the category and requires extra side indicators and a reversing lamp.
- Ride. Western Australia warns that an upgraded vehicle "will have a noticeably harder and stiffer ride than a standard vehicle, especially when lightly laden".
- Warranty. Regulators tell owners to check with the vehicle maker first. Isuzu UTE's owner FAQ says suspension changes that increase load capacity can affect warranty, because they affect the chassis, steering, axles and stability control. Kit makers generally say warranty is kept when their kit is fitted before registration. Get the answer for your vehicle in writing.
- Insurance. Tell your insurer. AAMI, for example, asks to be told about modifications and says it covers legal modifications. An uncertified upgrade is not a legal one.
- Speed in NSW. When towing with a combination over 4.5 tonnes GCM, the limit in NSW is 100 km/h whatever the sign says. Most large tow vehicles with a caravan are already over that, upgrade or not.
Who Supplies GVM Upgrades?
The suppliers below are listed alphabetically, with what each says on its own website. Figures are the suppliers' own, and each applies only to that supplier's kit on the named model.
| Supplier | Before registration | After registration | An example it publishes |
|---|---|---|---|
| ARB / Old Man Emu | Yes | Through its state offices | — |
| Dobinsons | Yes | Yes | LandCruiser 300: up to 3,990kg |
| EFS | Yes | — | Ford Ranger: 3,230kg to 3,700kg; Isuzu D-MAX: 3,100kg to 3,650kg |
| Ironman 4x4 | Yes | Yes | Toyota HiLux (2026): 3,065–3,120kg to 3,500kg |
| Lovells | Yes | Depends on the state | LandCruiser 300: 3,280kg to 3,600kg, 3,805kg or 4,205kg |
| Pedders | Yes | Via a state engineer | — |
| Tough Dog | Yes | Via a state engineer | LandCruiser 300: 4,139kg; Ford Ranger: 3,750kg |
| West Coast Suspensions | Yes | Yes | LandCruiser 300: 3,800kg |
A dash means the supplier's site did not state it when we checked. TJM also sells GVM kits (XGS GVM Plus) for the Ranger, D-MAX, HiLux and LandCruiser, but its site published no figures.
A few things stand out:
- The same vehicle gets different figures from different suppliers. For the LandCruiser 300 the upgraded GVM ranges from 3,600kg to 4,205kg depending on the kit. Each figure belongs to that supplier's approval and parts.
- Most suppliers upgrade GVM only. West Coast Suspensions says plainly that its upgrades "do NOT increase the Gross Combined Mass (GCM) or Braked Towing Capacity (BTC)". Lovells also offers GCM and braked towing capacity revisions on some models; see the state positions above before relying on one.
- Toyota now offers its own. From August 2026 Toyota sells a factory-fitted GVM upgrade for the HiLux, priced from $4,000, which adds 372 to 435kg of payload and keeps the factory warranty.
What a Kit Includes
Typically front and rear springs, matched shock absorbers, and the paperwork: an owner's manual, a revised tyre or load placard, and the federal registration entry for a pre-registration upgrade. Some kits add bushes, U-bolts, upgraded indicators or brake parts, depending on the vehicle.
What It Costs
No government body publishes a typical price, and state engineering fees are set by the certifier. The few prices suppliers publish give a rough guide:
- Toyota's factory HiLux option: from $4,000.
- Dobinsons, LandCruiser 300: $4,790 to $6,150 supplied and installed, with state engineering extra where it applies.
- Ironman 4x4, HiLux: about $3,700 to $4,250 for the kit.
- EFS: from about $3,100 (Isuzu D-MAX) and $3,650 (Ford Ranger) for the kit.
Ask for a quote that includes fitting, certification for your state and any tyre or indicator changes the approval requires.
Do You Need One?
- Weigh the rig as you travel. A public weighbridge gives you the vehicle's actual loaded weight, each axle and the combination. Our weighbridge helper lists which readings to ask for and checks them against your limits.
- Compare with every limit, not only GVM: both axles, GCM, towing capacity and tow ball download.
- Try the cheaper fixes first. Moving weight from the vehicle to the caravan (within the van's own limits), carrying less water, or removing accessories you don't use costs nothing.
- If you are over GVM but comfortably under GCM, a GVM upgrade is the right tool.
- If you are near or over GCM, a GVM upgrade will not make the combination legal. You need a lighter van, less load, or a vehicle with a higher GCM.
Frequently Asked Questions
Does a GVM upgrade increase towing capacity?
No. Braked towing capacity stays at the manufacturer's figure. And because GCM normally stays the same too, loading the vehicle to its new GVM reduces the weight you can tow.
Is it better to upgrade before or after registration?
Before, if you can. A pre-registration upgrade is done under one federal approval and is treated as recognised nationally. An upgrade after registration is approved under state rules, and NSW and Western Australia do not simply accept another state's certification.
Will a GVM upgrade be recognised if I move interstate?
A pre-registration upgrade generally is. An in-service one depends on the state: Tasmania recognises legitimate interstate modification plates, NSW does not recognise interstate certificates, and Western Australia requires the vehicle to be assessed there.
Can any 4WD get a GVM upgrade?
No. A kit must exist and be approved for that model, and Queensland and Western Australia only allow in-service upgrades on ladder-chassis vehicles.
Do I need a different licence?
Only if the upgrade takes the GVM above 4.5 tonnes, which makes it a heavy vehicle. Kits for popular tow vehicles are set below that.
Does a GVM upgrade affect my warranty or insurance?
It can. Ask the vehicle maker about warranty before fitting, and tell your insurer. Insurers ask to be told about modifications and cover legal ones; an uncertified upgrade may leave you without cover.
The Bottom Line
A GVM upgrade solves one problem: a tow vehicle that is over its own weight limit. It does not let you tow more, and with an unchanged GCM it can mean towing less. Get the rig weighed, check it against every limit with the rig loading simulator, and if an upgrade is the answer, choose the pre-registration route where you can and confirm how your state treats it. If you are still choosing a van, the tow-match checker will tell you whether a given caravan suits your vehicle before weight becomes a problem.
