Your car can tow only as much as its lowest applicable limit allows. That may be the vehicle's braked or unbraked towing capacity, the towbar rating, the maximum towball load, the vehicle's Gross Combination Mass (GCM), or the trailer's own weight limit.
You also need to allow for the trailer's load. A trailer that weighs 400 kg empty may weigh 700 kg once loaded with soil, furniture, or building materials.
Your towing limit is the lowest applicable rating
Check all of the following:
- the vehicle manufacturer's braked and unbraked towing capacities
- the towbar's maximum towing rating
- the vehicle and towbar maximum ball-load ratings
- Gross Combination Mass, if specified for the vehicle
- Gross Vehicle Mass (GVM) and axle-load limits
- the trailer's ATM, tare, and available payload
- any special conditions in the vehicle handbook, such as reduced towing capacity when the vehicle is heavily loaded
You must remain within all applicable limits, not just the advertised car towing capacity. These ratings measure different things, so do not treat every number as interchangeable and pick the smallest.
Do not guess from engine size
Two similar cars can have different tow ratings. Always use the handbook, compliance information, and towbar plate for your exact vehicle and accessory fit-out.
Find your vehicle limits
- Open the owner’s handbook towing section and note braked and unbraked capacities.
- Check the vehicle compliance plate / build information for GVM and related ratings.
- Inspect the towbar rating plate for maximum tow and ball load.
- If the towbar or removable towbar tongue is aftermarket, confirm that it is approved for your exact vehicle variant, correctly installed, and being used in an approved orientation.
- Allow for passengers, fuel, and cargo already in the car; they count toward GVM.
RACQ notes that the vehicle specification remains the maximum the vehicle can legally tow, even if a towbar is stamped with a higher figure. If the towbar is lower, the towbar wins.
Worked example: how to calculate towing capacity
Suppose your vehicle lists:
- 1,500 kg braked towing capacity
- 750 kg unbraked towing capacity
- 150 kg maximum ball load
- 3,500 kg GCM
Your towbar is rated to:
- 1,200 kg maximum trailer weight
- 120 kg maximum ball load
For a braked trailer, the towbar reduces the maximum trailer weight from 1,500 kg to 1,200 kg. The maximum permitted ball load is 120 kg because that is lower than the vehicle's 150 kg limit.
You must then check that the loaded vehicle and trailer remain within GVM, axle-load, and GCM limits. If the vehicle is already heavily loaded with passengers and luggage, the full 1,200 kg trailer capacity may not be available.
Match the trailer to your car
Find the trailer's tare, ATM, and, where provided, GTM on its compliance plate / VIN plate or registration information.
- Tare is the trailer's stated empty mass.
- ATM is the maximum permitted total mass of the loaded trailer, including the portion supported through the coupling by the tow vehicle.
- GTM is the maximum mass carried by the trailer's wheels when it is connected.
- Payload is generally ATM minus tare.
Estimate the weight of everything you plan to put in the trailer. The trailer's expected loaded mass must remain within the trailer's ATM and the applicable vehicle and towbar towing limits. Learn more about trailer tare and ATM in the trailer weight guide.
Do not rely blindly on tare
Accessories, cages, ramps, spare wheels, and modifications may increase the trailer's actual empty weight. When the margin is small, ask the owner or use a weighbridge.
Check the ball load separately
Ball load is the downward force the trailer places on the towball. It is not a fixed plate figure: it changes with the trailer's total weight and where you place the load. The trailer weight guide explains how ball load relates to ATM and GTM.
A common guide is around 10% of the trailer's loaded mass, but some vehicles permit substantially less or more. Follow all applicable vehicle, towbar, coupling, and trailer ratings, load the trailer as directed by its manufacturer, and do not exceed the lowest applicable ball-load rating.
To check the actual ball load after loading:
- Load the trailer as you intend to tow it, with the coupling at roughly the same height as your towball.
- Place a suitable scale under the coupling or under the lowered jockey wheel so the scale supports the front of the trailer. The reading is the ball load.
- Alternatively, use a weighbridge: weigh the tow vehicle alone, then weigh it again with only the vehicle on the scale and the loaded trailer coupled behind it. The difference is the ball load transferred to the vehicle.
If the reading is too high, move some load rearward. If it is too low or the trailer feels light on the hitch, move some load forward. Recheck after any change.
Trailer brakes and brake controllers
Your vehicle handbook will state its maximum unbraked and braked towing capacities. The maximum unbraked capacity cannot exceed 750 kg and may be lower for your vehicle.
Australian light-trailer requirements generally use GTM for brake thresholds:
- trailers up to 750 kg GTM may be unbraked, subject to the vehicle's lower unbraked limit
- trailers over 750 kg and up to 2,000 kg GTM require brakes on at least one axle
- trailers over 2,000 kg GTM require brakes on all wheels and a system that applies the trailer brakes if the trailer becomes detached
Mechanical or hydraulic brakes normally do not require an in-car electric brake controller. Electric brakes generally do. Check the listing and confirm the brake type and controller requirements with the owner before booking.
State and territory rules
National vehicle standards cover many trailer requirements, but road-use and licence rules can vary between states and territories. Check your local transport authority for:
- learner and provisional licence towing restrictions
- towing speed limits
- load restraint and overhang requirements
- registration and lighting requirements
- any rules that apply when travelling interstate
Check the official guidance for NSW, Victoria, Queensland, Western Australia, South Australia, Tasmania, the ACT, and the Northern Territory.
Once you know your limit, compare local listings and choose a trailer type that fits the job using box vs cage trailer.
Check again before leaving
- Confirm the trailer’s tare and ATM.
- Confirm whether its brakes are mechanical, hydraulic, or electric.
- Check that your vehicle has the required brake controller.
- Make sure the coupling matches the towball.
- Attach the safety chain or chains correctly.
- Test the lights and brakes.
- Estimate the cargo weight and keep it within the trailer payload.
- Load heavy items low and close to the axle area.
- Secure the entire load.
Ask the owner before pickup if any trailer weight or brake information is missing from the listing.
Towing capacity FAQ
Can I find my towing capacity using my registration number?
Some manufacturer, dealer, or motoring-service tools may provide vehicle specifications from registration or model details. Verify the result against the handbook for your exact model, year, engine, and transmission.
Does towball weight count towards vehicle payload?
Yes. The load placed on the towball contributes to the load carried by the towing vehicle and can affect its GVM and rear axle load.
Can I tow a trailer with a higher ATM if I do not fully load it?
Do not assume that partially loading a higher-ATM trailer makes the combination acceptable. Vehicle-manufacturer wording and jurisdictional requirements can differ. Choose a trailer whose ratings are compatible with your vehicle and obtain specialist advice where the trailer ATM exceeds a stated vehicle or towbar limit.
Can my car tow a trailer?
It can if the loaded combination remains within every applicable vehicle, towbar, ball-load, axle-load, GCM, and trailer limit, and your vehicle has the equipment the trailer requires.
