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In the vast majority of cases, the reason why touring builds are overloaded does not come from adding one large component. The fact of the matter is that when you start adding your bull bar, your canopy, your drawer systems, your fridge, your water, your fuel, your passengers, and your loaded caravan towball into one vehicle in a period of months, nobody calculates the cumulative total of everything you have added.
The fact of the matter is that by the end of your build process, your vehicle is overloaded beyond its legal limits without the owner even realising this due to the lack of a dashboard warning light. This is exactly why a GVM upgrade Perth conversation should happen before the accessories go on, not after.
This guide covers the essential terminology surrounding vehicle weight and how to calculate it for your planned build, an example of a calculation of a common touring build, and information on the individual payload limitations for the ute and wagon which are generally used in Western Australia to help determine if you require certification.
This blog is intended to cover the exact query related to GVM upgrades WA (or Perth), i.e., is your plan going to take you over your available payload allowance, and what does this mean?
Weight terminology on a compliance plate looks simple until you try to use it to plan a build. Here is what each term actually means in practical terms.
Tare mass is the total weight of the automobile in its factory form with all the standard features on board, including the fuel tank, coolant, and other factory-installed equipment, but without any drivers, passengers, or extra equipment. It is important to understand that this weight is different from what your automobile weighs in your garage.
Kerb weight has a close relationship with tare mass and is frequently used as a synonym for it, although in Australia, it is more popular to find tare mass figures marked on compliance plates. After adding a bullbar, canopy, winch, drawer system, or even heavy-duty wheels and tyres, your real kerb weight becomes much higher than the initial tare mass from the factory.
Payload refers to the difference between your vehicle’s GVM and its actual weight at any particular time (which is the tare mass of your car plus all the accessories that have been installed). This is the figure that will be important in your build because it will tell you what is left for other items.
GVM, which stands for Gross Vehicle Mass, refers to the maximum weight allowed by law for a loaded vehicle, as determined either by the manufacturer or by a second-stage authorised manufacturer in case of modification. This definition only takes into consideration the vehicle itself and not any trailer.
GCM stands for Gross Combination Mass and is the greatest legal weight combination of the total weight of your vehicle along with an attached caravan/trailer. GCM is an entirely different concept to GVM, which means that a GVM upgrade for towing caravan setup does not necessarily lift GCM. This fact has got quite a few WA tourers caught out.
The front and rear axle limits are the maximum loads that each axle may legally carry, and both have to be adhered to even when the gross vehicle mass (GVM) of the car has not been exceeded. A canopy full of drawers, fridge and water tanks located behind the rear axle can exceed the load capacity of the rear axle long before reaching the overall GVM. This is one of the most common problems encountered during 4WD payload assessment Perth clients come in with.
Towball mass is the downward force that is exerted by the caravan/trailer on the towball, and it is subtracted from the payload of your vehicle and not the caravan itself. The tow-ball load of a caravan weighing 250 kg means that you will add another 250 kg directly to the payload of your ute/wagon the moment you hook up the caravan to the vehicle.
The following table displays the estimated accumulated weight for an average heavy touring configuration for a dual-cab ute. The exact numbers will depend on make and model, but this trend is consistent across practically all configurations we see at Sharp 4×4 in Cockburn and Myaree.
| Item | Approximate Weight |
| Steel bullbar | 60 to 90 kg |
| Winch | 30 to 40 kg |
| Driving lights and wiring | 5 to 10 kg |
| Underbody protection (bash plates) | 20 to 35 kg |
| Aluminium canopy | 100 to 180 kg |
| Drawer system | 40 to 80 kg |
| Fridge (loaded) | 40 to 55 kg |
| Dual battery and wiring | 20 to 30 kg |
| Rooftop tent | 45 to 70 kg |
| Water (80 litres) | 80 kg |
| Fuel (long-range tank, additional capacity) | 40 to 80 kg |
| Passengers (two adults) | 140 to 180 kg |
| Caravan tow-ball load | 150 to 250 kg |
Combine them all up, and it is normal for a truck to carry up to 700 to 1,100 kilograms extra over its tare weight before even loading any luggage. In many cases, dual-cab utes leave the factory with an actual payload capacity of just 850 kilograms to 1,000 kilograms considering that there are trays, tow bars and other dealer additions installed in it.
There is no need for mathematical accuracy here to get the point across: bullbars, canopies, drawers, fridges, water, fuel, people and a caravan towball can easily eat into the total payload in a medium-sized dual-cab or exceed it when towing one.
The payload number in the brochure is worked out from the tare weight of the factory without any options installed at all. It calculates the naked car. As soon as the dealer installs the tow bar, tinted windows, floor mats, tray or canopy, that payload number is going down. And before the car has even been delivered.
That is what surprises many WA tourers. A car advertised with 1,000 kilograms of payload may end up with 650 to 750 kilograms of actual payload after installing dealer options, a bullbar, canopy, and drawers. Include in the equation a rooftop tent, dual battery system, camping equipment, passengers and caravan ball load, and your payload will disappear completely.
And this is the reason why the GVM upgrade for touring vehicle builds has to be done with regard to the actual weight of the car and not the one from the specification sheet many years ago.
A weighbridge check is the only reliable way to know where a build actually sits, and it should happen at more than one stage of the process.
Public weighbridges can be accessed in many parts of the Perth metro area, and a full weighing report must be retained for inclusion in the vehicle’s build history. This is necessary in case there arises the need for a certified GVM upgrade Perth engineer to consider the vehicle’s loading state in reality.
A handful of practical signs tend to show up before a vehicle is technically overloaded, and they are worth taking seriously.
Any one of these signs is a reasonable trigger for a proper 4WD payload assessment Perth owners can book before committing further money to the build. To better understand this, read our guide on how accessories eat your payload and make your vehicle overweight.
Another very popular platform for a heavy-duty remote touring or work vehicle is the 79 Series, and this is due to the relatively high payload capacity that is provided by this vehicle when using the stock components.Â
Nevertheless, even when you install such components on your vehicle as the steel tray, canopy, long-range fuel tank, winch bar and dual battery setup, then there is not going to be much payload capacity left in the factory payload limit. The suspension upgrades will be combined with shock absorbers with a LandCruiser 79 GVM upgrade Perth.
Although the 300 Series comes with an impressive payload capacity out of the factory, even the fully optioned wagon equipped with a roof tent, drawer, twin battery system, bull bar, winch, and heavy caravan tow ball may still eat up the existing payload quickly, especially for the higher models that already have more fitted equipment at the factory level. A typical LandCruiser 300 GVM upgrade Perth will involve suspension parts that can cope with the combined weight of all the touring gear and a family-style caravan, rather than a tall lift height.
Current Ranger models have a small load capacity from the factory, considering all the accessories which are usually added by dealers, and this is among the most common models used by Sharp 4×4 for canopy and caravan fitment.Â
A Ford Ranger GVM upgrade Perth service would be the only solution between a Ranger capable of towing a canopy, drawers, fridge, and mid-sized caravan and one which becomes overloaded just by getting in the family members and gear.
The Hilux has a profile that is close to that of the Ranger, with a factory load capacity that reduces rapidly as soon as accessories such as the steel bull bar, canopy, extended fuel tank, and drawer are installed.Â
The Hilux GVM upgrade Perth generally involves the upgrade of the springs and shocks according to the weight of the accessories to be installed in the vehicle, as an off-road tourer is completely different from an off-road workhorse.
The D-MAX has some real factory payload capability within the mid-size dual-cab category, but fitting out a full touring load-out, complete with canopy, tent on roof, dual battery, and towing a fully laden caravan, could easily take it to the limit or beyond. The typical Isuzu D-MAX GVM upgrade Perth package would be focused around an enhanced suspension system to cope with the added weight.
The Everest is built on a wagon platform and, in terms of the factory payload capacity, is significantly smaller than the comparable Ranger ute when all factors are taken into account. An Everest with roof rack systems, rooftop tents, drawers, a fridge, and a tow ball is one of the quickest ways to go beyond the factory payload limit, and it is highly advisable to have a good weight test done before building the touring package on an Everest.
A GVM upgrade is an engineered modification and not merely a superficial one. In most cases, a GVM upgrade consists of more than just replacing a component; it often entails the interplay of several components. A GVM upgrade can consist of:
This is the engineering that goes into every genuine GVM upgrade after canopy installation or GVM upgrade before bullbar installation conversation. The suspension needs to be matched to where the actual load resides on the vehicle, and that is why a generic/universal lift kit is not equivalent to an engineered GVM upgrade, although the two are often installed together.
This is undoubtedly one of the most misunderstood aspects of the entire process and deserves to be discussed separately rather than in brief terms. An upgrade to the GVM of a vehicle results in an increase in the maximum permissible weight of the vehicle. However, it does not automatically mean that there will be an increase in the GCM and/or manufacturer’s braked towing capacity of the vehicle.
What this means is that it is quite possible that a vehicle, which has undergone an upgrade to its GVM, will be able to tow a lesser amount than it was doing before the upgrade due to the fact that more of the constant GCM is used up by the weightier vehicle, leaving very little for the trailer or caravan.
Anyone intending to make a GVM upgrade for towing caravan configuration needs to take into account the GCM value rather than just the GVM and see what towing allowance is left.
The Western Australia regulatory system has a different approach to these two GVM upgrading pathways, and the pathway open to a particular vehicle will depend greatly on whether the vehicle has been registered or not.
A pre-registration GVM upgrade WA conversion refers to the GVM upgrading of a vehicle that has not been registered before, and the pathway followed here will be the second-stage manufacturer approval, and this pathway offers a wider variety of upgrades since the vehicle has not yet been put into service.
A post-registration GVM upgrade WA conversion is performed on an existing and operating vehicle. It goes through a different process of certification and approval, and also, it has a more limited range of options based on the vehicle and conversion performed.
They both require engineering certification in the process, which varies enough to deserve its own discussion. The difference between these two approaches has been explained quite well in Sharp 4×4’s separate article. You may wish to have a look at it prior to determining what pathway you need: GVM Upgrade Explained: Payload Math for Touring Builds.
Every certified GVM upgrade in Western Australia needs to be traceable back to an approved engineering signatory and a documented inspection process. In broad terms, the process involves:
It is expected that a certified GVM upgrade Perth service provider will guide you through the process of doing all this and give you all the required documents for the registration, insurance and resale process.
It is important that you keep all the documents along with your car because any future purchaser, insurance agency or inspector will require proof of certification.
Use this simple worksheet as a starting point before committing to accessory purchases.
Running this worksheet before purchasing the canopy, drawer system, or caravan prevents the all-too-common situation in which each purchase makes sense in its own right but results in exceeding the weight capacity of the vehicle.
Light configuration: Either a tray or a lightweight canopy, a single battery setup, a small refrigerator, little drawer space, and sometimes short distances travelled by two persons. This setup will fit into many factory-made trucks without adding any extra load, although it should be checked on a weighbridge anyway.
Medium configuration: The combination of either an aluminium or steel canopy, drawers, a twin battery arrangement, a rooftop tent, a long-range fuel tank, and frequent trips with two to four occupants along with reasonable camping gear. It is at this point that the dual-cab utility vehicles begin to get close to or surpass the payload capacity of the vehicle, and this becomes the most common reason for a GVM upgrade quote Perth request.
Heavy configuration: All of the above, together with a bullbar and winching outfit, underbody protection, increased water capacity, a family of four or more, and the regular towing of a caravan with heavy tow ball weight. This is the sort of setup that virtually guarantees the need for an official increase in the GVM of a medium-sized vehicle and often warrants it in larger vehicles as well.
An enquiry from a customer based in Perth had an existing dual-cab ute with a steel bullbar, aluminium canopy, drawer system and dual battery, intending to fit a family-size caravan for touring in Western Australia.
A weighbridge test in trip trim, with the vehicle being weighed in the condition it would travel on a normal tour, revealed that the vehicle weight was already slightly under its factory GVM without even considering the additional tow-ball weight of the caravan.
The team at Sharp 4×4 conducted a full payload analysis, determined the required GCM for the desired caravan and installed a GVM upgrade kit, designed specifically for the vehicle in question and the specific accessory load, installing new springs and shock absorbers suitable for the canopy, drawers and towing applications.
The upgrade was engineer-approved, registered, and documented according to the proper WA procedure, providing the customer with a legal and engineering-calculated allowance for fuel, water, passengers, and caravan tow-ball for every tour, rather than a vehicle that was simply near its limit on paper.
Pricing varies by vehicle, target GVM, and needed components. A GVM upgrade quote Perth provides the most accurate estimate for your build.
Yes. The real deal of GVM modification in Western Australia entails engineering certification in an accepted way, regardless of whether it has been done prior to registration of the vehicle or after. No engineering certification means that no GVM has been raised even if you feel that the car has been modified to raise its capabilities.
Notify your insurance company of GVM changes and updated compliance plates to ensure your policy reflects the new weight limit and avoid claims issues.
GVM upgrades increase vehicle weight limits, but GCM and towing capacities remain manufacturer-set, potentially reducing available GCM for trailers.
Lead time for components varies, ranging from days to weeks. Early booking for 4WD payload assessment Perth ensures flexibility in timing and selection.
GVM upgrade before bullbar installation or GVM upgrade after canopy installation depends on confidence in weight estimates and whether the suspension needs matching to final weights.
Hunches on payload amounts are why tourers build end up being overweight, without this fact coming to light until the vehicle hits a weighbridge, the insurance company, or a roadside check. You should get an accurate weight check for the current payload status before ordering any canopy, bull bar, drawer system, or caravan.
GVM upgrade Western Australia is a process undertaken by Sharp 4X4’s qualified teams at Cockburn Central and Myaree, which will provide a GVM upgrade solution tailored to your specific vehicle, accessories, and towing needs, from the very first assessment to the completion of all GVM upgrade engineering and certification.
Contact us to get your GVM and payload assessment done by booking an appointment at Sharp 4X4 today and start your GVM upgrade Perth on your touring rig right from day one.
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