This page describes the legal requirements in the Land Transport Rule: Vehicle Dimensions and Mass 2016. It also includes information about subsequent relevant legislation.

Information can also be found to help road controlling authorities with the VDAM rule 2016


Vehicle dimension and mass permitting

The Vehicle dimension and mass permitting manual (the VDAM manual) states the NZ Transport Agency’s policies, standards, processes and procedures for the permitting of vehicles exceeding standard dimension and mass limits. The manual is the authoritative body of knowledge for all heavy vehicle permitting and supersedes the Transport Agency’s Overweight Permit Manual and Draft HPMV Manual.

The manual consists of two volumes:

Volume 1: Information for operating under an overweight, overdimension and HPMV permit

Volume 2: Process and procedure information for permitting staff

High productivity motor vehicle (HPMV) permits

If you want to carry divisible loads, such as logs, milk powder or freight, more productively, you may be able to operate on a HPMV permit.

Overweight and overdimension permit types

Vehicles travelling on New Zealand roads must be within a certain size and weight. This is so they can fit on the road safely – get around corners, fit under bridges, etc.

The maximum size and weight dimensions for vehicles are set out in the Land Transport Rule: Vehicle Dimensions and Mass 2016. But sometimes, larger or heavier vehicles need to use the road. This commonly includes farm vehicles and vehicles used in house relocation.

Find out more about overweight and overdimension permits on the Overweight permitting page.

What are the general mass (weight) limits on New Zealand roads?

The words ‘mass’ and ‘weight’ are both used, but they mean the same thing. For example a vehicle’s tare (in kilograms) is its unladen mass, but you would measure it by using a weighbridge.

There are two different types of mass limit that apply to your vehicle and its load.

The limitation imposed by the vehicle’s design and construction. You must not exceed the vehicle ratings specified by the vehicle manufacturer for the chassis, axles, tyres and other components of the vehicle. For example, you are not allowed to load your vehicle above the specified maximum gross vehicle mass (GVM), gross combination mass (GCM), brake code mass (BCM) or tow a load greater than the drawbar is rated for.

Limits to axle mass are imposed to protect the road infrastructure. This is because certain sections of roads in New Zealand are not built to the same strength specifications as in other countries.

To find the operating gross mass (weight) of your vehicle, add the tare mass of the unladen vehicle to the mass of the load the vehicle is carrying. You must take into account any mass transferred to the rigid vehicle by an attached trailer. You can also measure this mass by using a weighbridge. This total mass must not exceed any of the vehicle’s design limits or the road limits.

Axles can have different types of tyres fitted to them, and the allowed mass changes depending on which type you are using.

S = Single standard-tyred axle (includes two axles spaced less than 1 metre apart)

SL = Single large-tyred axle – tyres at least 330mm (13 inch) width by 24 inch diameter or 355mm (14 inch) width by 19.5 inch diameter (includes two axles spaced less than 1 metre apart)

T = Twin-tyred axle.

The limits on the weight of vehicles on New Zealand roads and bridges have been introduced to protect roads that are designed and are maintained to a level called 'class 1'.

Note: Some roads and bridges have lower weight limits than class 1. These lower limits have been imposed by the road controlling authority (RCA) to protect particular bridges or roads from damage. These special limits are indicated on road signs that read 'Class C' or 'Heavy vehicle axle limit' or 'Heavy vehicle bridge limits'. Only vehicles within the specified limits can use these roads or bridges.

For example, if you want to cross a bridge displaying the above sign, then an individual axle (not axle set) must not exceed 4300kg, each axle set must not exceed 50% of the axle set limits in the rule, and the vehicle must not travel over the bridge faster than 15km/h. Note that some of these signs will not have all three restrictions listed, for example if there is no speed listed, you can cross at the appropriate speed.

You can find further information on vehicle dimensions and mass on the NZ Transport Agency site, including trailer:truck mass ratio, static roll threshold, axle mass limits, dimension limits and how to determine dimensions, projecting loads, towing and definitions and specifications.

For further information contact the Team Leader Freight and Register Records.