WEIGHT FOR IT: THE FULL TRUTH ABOUT GVM
Let’s get one thing straight: for most people, relaxing at a campsite or dropping a line on the water is far more fun than whipping out a calculator and doing maths. With that obvious truth out there, we have some bad news for you – if you love to load up your rig or pull something in tow, it pays to do the maths before you head for the horizon.
The simple truth is that your vehicle’s Gross Vehicle Mass (GVM) is the limit of how much your rig can weigh while remaining roadworthy. Vehicles that aren’t roadworthy aren’t legal to drive, but this ‘roadworthiness’ tag isn’t just there to catch people out with fines – it’s there to make sure vehicles, their drivers, passengers and other vehicles on the road are safe. A vehicle that’s over its GVM doesn’t handle well, can’t perform evasive maneuvers properly and can create excessive wear and tear (or straight up breakages) in your vehicle. Plus, if you’re in an accident and your insurance company recovers your vehicle and finds that it’s over its GVM, they may not pay up and you’ll be out of pocket.
Picture this: you have a 200 Series LandCruiser – which has an initial payload of 650kg and a GVM of 3350kg – that you plan to take across the Top End. You want it to be ready for long-range 4WD touring, so you send it to your local TJM to get a steel bull bar (75kg-115kg), underbody guards (10kg-50kg), winch (35kg), side bars and steps (55kg), rear step tow bar (80kg), awning (15kg), auxiliary battery (30kg), long range fuel tank (120kg loaded) and roof rack (25kg). That equates to up to 525kg of added weight, meaning you have only a 125kg payload remaining for all your passengers, cargo, the tow ball down weight of anything you’re towing and other accessories before it exceeds its GVM. Which, unless you travel solo with no fridge, water or cargo of any kind, it would be a tough ask to stay under your legal GVM.
So, we know GVM is about vehicle weight, but what part of your vehicle is responsible for handling it? The answer is suspension. Unfortunately, the suspension that comes with your vehicle when you buy it new is designed for on-road driving and minimal loads, so if you plan on going four-wheel driving and carrying plenty of cargo, it won’t be up to the task. The answer to this problem is a good suspension upgrade, which will give you a better driving experience, better load-carrying capability and higher clearance for when you go off-road.
This means that, if you want to get all the benefits of a suspension upgrade with the added bonus of an increased GVM rating, you may want to consider getting a GVM upgrade. A GVM upgrade is, essentially, a special kind of suspension upgrade that’s been tested and certified to increase the safe and legal load-carrying capability of a vehicle.
This certification process is a long one, but it ensures that any proposed GVM upgrades can properly handle the loads they say they can carry – meaning car owners who get the upgrade can do so with confidence in the upgrade they’re getting. To get certified, the proposed suspension system gets sent to a third-party testing facility, and from there the fun begins.
These facilities independently test these suspension systems in a heap of fancy ways. This ranges from actually analysing the materials that the suspension components are made from to loaded and unloaded real-world driving tests – even to using vehicle-mounted sensors to see how well a heavily loaded vehicle performs evasive maneuvers (comparing this data to OE unloaded vehicles). This whole process can take up to six months, which goes to show the depth of investigation that goes into approving every single GVM upgrade.
Once a suspension system has been tested and given the all-clear, it then transforms into a true-blue GVM upgrade. The amount that a vehicle can increase its GVM by is dependent on a few things (such as chassis and component strength), which is why GVM increases for different vehicle models are not the same. Most GVM upgrades will increase the GVM of a 4WD by between 300kg-550kg, giving you plenty of extra load-carrying capacity to hit the road with peace of mind and an improved driving experience to boot. Using our example of our adventure-ready 200 Series, a TJM GVM Plus upgrade increases the 200’s GVM from 3350kg to 3800kg, meaning our fully-loaded 4x4 has an extra 450kg payload – which then means you can take more people, carry more cargo and travel further for longer.
So now we have a better understanding of GVM and its importance, what can you do to run the numbers and ensure you’re legal and safe? The answer is a pretty simple one: load up your rig as if you’re heading out for a trip, then head down to a weighbridge and get it all weighed up together. Then you will know, without a shadow of a doubt, how close (or over) to your GVM your full setup is. Who knows – the answer might surprise you!