The short answer
You need a GVM upgrade when your loaded vehicle, plus the caravan's ball weight, is heavier than the vehicle's Gross Vehicle Mass. Many dual cabs and wagons reach that point once they have a bar, canopy, drawers, fridge, water and passengers on board.
How to check
- Find your GVM on the compliance plate or in the owner's manual
- Weigh the vehicle loaded for a trip, at a public weighbridge
- Add the caravan's ball weight, usually around 10% of its loaded weight
- If the total is over GVM, you're overloaded and may not be insured
What an EFS GVM upgrade changes
An EFS GVM upgrade replaces the springs and shocks with a kit engineered and tested for a higher GVM, and the vehicle gets a new compliance plate. It has to be done properly to be legal. Heavier loads also mean longer stopping distances, so we check brakes at the same time. For the numbers on every kit, see how much payload a GVM upgrade adds.
Within your GVM but sagging at the rear? You may only need springs rated for your constant load. See EFS lift kits, or go to EFS GVM upgrades.
Written by the team at EFS Gold Coast, The Garage Miami. Updated October 2026.