Car Load Ratings Explained: Payload, GVM, Towing & Roof Limits
Your car has legally mandated weight limits that most people have never thought about — until they're cited by police at a weighbridge or their suspension fails after a heavy move. Here's what the numbers actually mean and how to stay within them.
10 min read
Key Weight Ratings: What Each One Means
Kerb Weight
The weight of the vehicle with a full tank of fuel and all standard equipment, but no passengers or cargo. This is the baseline from which all other weight calculations start.
Example: A Toyota RAV4 has a kerb weight of approximately 1,700kg.
Gross Vehicle Mass
GVMThe maximum legal total weight of the vehicle, including the car itself (kerb weight), all passengers, all cargo, all accessories, and all fluids. This is the hard legal limit you cannot exceed.
Example: The same RAV4 has a GVM of approximately 2,250kg.
Payload Capacity
GVM minus Kerb Weight = the maximum combined weight of passengers + cargo + accessories you can add to the car. This is the most practically useful figure.
Example: RAV4 payload: 2,250 - 1,700 = 550kg for everything on board.
Gross Combined Mass
GCMMaximum legal total weight of the vehicle AND a trailer combined. The GCM minus the vehicle's GVM gives you the trailer's maximum legal weight.
Example: If GCM is 4,500kg and GVM is 2,250kg, your maximum trailer weight is 2,250kg.
Towing Capacity (Braked)
Maximum weight of a trailer with its own brakes. Unbraked towing capacity (trailers without brakes) is significantly lower — typically 750kg regardless of vehicle.
Example: Most mid-size SUVs: 1,500–3,500kg braked towing capacity.
Roof Load Rating
Maximum combined weight of roof racks + cargo that can be placed on the roof. Separate from the GVM calculation — you need to comply with both. Typically 50–100kg including the weight of the rack itself.
Example: Most passenger cars: 50–75kg. Many SUVs: 75–100kg.
How to Find Your Car's Ratings
Your vehicle's weight ratings are found in three places:
- Owner's manual: The most comprehensive source. Usually in the specifications section or under 'loading your vehicle'.
- Door jamb placard: A sticker on the driver's door edge or door jamb lists GVM and sometimes tyre pressure for different load states.
- Online: Search for your exact make, model, and year followed by "specifications" — most manufacturers publish these in the official spec sheet.
Practical Implications for Heavy Loads
Why Exceeding Limits is Dangerous
- • Braking distances increase significantly — an overloaded car cannot stop as quickly
- • Steering response and handling degrade — particularly in emergency manoeuvres
- • Tyre blowout risk increases — tyres are rated for specific loads
- • Suspension damage accumulates — and this typically isn't covered by warranty or insurance if caused by overloading
- • Insurance may be void if an accident occurs while the vehicle is overloaded
- • Police can issue fines at weighbridges or random checks
The most common overloading scenario: 4 adult passengers (approximately 300kg) + luggage (100kg) + roof box and contents (80kg) = 480kg — already close to a typical 550kg payload, and that's before any additional cargo.
How to Calculate Your Available Load
A simple formula to check before a heavy trip:
GVM (from specs)
− Kerb weight (from specs)
− Weight of passengers (estimate 80kg/person)
− Weight of roof rack + cargo
= Maximum cargo weight you can put in the boot
Example: GVM 2,000kg − Kerb 1,500kg − 2 passengers at 80kg each = 340kg remaining. If the roof rack and box weigh 50kg, you have 290kg for boot cargo.
Check If Your Load Fits Safely
Use stowey to check cargo volume and get loading suggestions — and always cross-reference with your car's payload rating for heavy loads.
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