How to weigh your rig
- Drive the whole rig onto the bridge, all wheels on. This is your combined weight, to compare with the vehicle's GCM.
- Move forward until only the vehicle's wheels are on the bridge, trailer still hitched. This is the vehicle with the towball download on it, to compare with GVM.
- Unhitch the trailer away from the bridge, then weigh the vehicle on its own. The difference from step 2 is the towball download.
Some weighbridges can also weigh each axle separately, which lets you check axle limits from the owner's manual. Our guide to weighing a caravan at a weighbridge goes through each step.
Worked example
Readings of 5,600 kg, 3,100 kg and 2,850 kg give a GTM of 5,600 − 3,100 = 2,500 kg, a towball download of 3,100 − 2,850 = 250 kg, and a trailer weight of 2,500 + 250 = 2,750 kg. Take these numbers to the towing calculator to check them against your limits.
Common questions
- How many weighings do I need at a weighbridge?
- Two readings give you the combined weight, the vehicle's weight with the trailer hitched and the trailer's axle load (GTM). A third reading of the vehicle on its own, unhitched, gives you the towball download and the trailer's full weight.
- Should the trailer be hitched when weighing the vehicle?
- For the GVM check, yes. The vehicle must be under GVM with the towball download on it, so weigh it hitched with only the vehicle's wheels on the bridge.
- Can I use a weighbridge for free?
- Many public weighbridges charge a small fee. Some councils, grain receival sites and transport depots offer public weighing. Call ahead, ask for a ticket for each reading, and go loaded exactly as you'll travel.
Sources
- Vehicle Standards Bulletin 1 (Revision 6): trailers with an ATM of 4.5 tonnes or less (August 2026), Australian Government, Department of Infrastructure
- Towing a trailer or caravan, NSW Government (Transport for NSW)
Rules checked against these sources on 12 October 2026. See rules, sources and method.