Regulation limits for motor vehicles and trailers
To be registered, a heavy vehicle must comply with regulation limits unless the vehicle has an exemption issued by the National Heavy Vehicle Regulator (NHVR).
Refer to Schedule 6 in Heavy Vehicle (Mass, Dimension and Loading) National Regulation for more information about the prescribed dimension requirements for heavy vehicles.
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Axle configuration
A heavy vehicle, other than an articulated bus, must have only:
- 1 axle group, or a single axle, towards the front of the vehicle
- 1 axle group, or a single axle, towards the rear of the vehicle.
A single axle means 1 axle, or 2 axles less than 1m apart.
An axle group means a tandem axle group, twin-steer axle group, tri-axle group or quad-axle group.
A tandem axle group means a group of at least 2 axles with the outermost axles at least 1m (but not more than 2m) apart.
A twin-steer axle group means a group of 2 axles with single tyres, fitted to a motor vehicle and connected to the same steering mechanism with the axles at least 1m (but not more than 2m) apart.
A tri-axle group means a group of at least 3 axles with the outermost axles more than 2m (but not more than 3.2m) apart.
A quad-axle group means a group of 4 axles, with the outermost axles more than 3.2m (but not more than 4.9m) apart.
Relation between axles in axle group
The axles in an axle group, other than a twin-steer axle group, must relate to each other through a load sharing suspension system.
Load sharing suspension
Load sharing suspensions are designed so that each axle in a group carries the same load irrespective of the relative movement of the wheels.
Find out more about load sharing suspension systems.
More information
- Last updated 12 July 2022