Your Guide to Towing Safely In New Zealand

Towing in New Zealand is as rewarding as it is challenging. From winding coastal highways to steep alpine passes, every journey puts unique demands on your vehicle, trailer, and driving skills. Whether you’re hitching up a caravan for a summer road trip, towing a boat for a fishing weekend, or hauling gear for work, safe towing requires more than just attaching a trailer and hitting the road. It’s about understanding your limits, choosing the right gear, balancing your load, and adjusting your driving habits. This guide combines expert towing insights with practical advice, giving you the knowledge you need to tow with confidence wherever your travels take you.

Identify Your Towing Requirements

After identifying whether your towing vehicle and trailer combination is classified as a light or heavy combination of vehicles, the very next step to safe towing is working out exactly what you’ll be towing, where you’ll be taking it, and how often you plan to travel. A small box trailer used occasionally for garden waste will have very different requirements from a fully loaded tandem-axle caravan headed across the South Island, and different again to a heavy vehicle combination rated more than 3.5T and used commercially on forestry roads for 5-days per week.

Consider the type of trailer, the weight of your load, and the road conditions you’ll face. Will you mainly be towing around town, where sharp corners and frequent stops are common? Or will your journeys take you onto gravel roads, over hilly terrain, or through long stretches of highway driving?

Each scenario requires a slightly different towing setup and will potentially be governed by very different regulations. Towing frequency also matters. If you tow only a few times a year, you may need only the basics, but if you tow regularly, investing in high-quality gear like heavy-duty suspension, upgraded mirrors, or a weight distribution system can save you stress and improve road user safety over the long term.

Tip: Always work off the lowest rating between your towbar, vehicle, and trailer. This ensures you stay safe and compliant.

Understand Vehicle Towing Capacity and Terminology

Every vehicle comes with a set of towing ratings that define what it can safely tow. These include the maximum trailer weight, maximum down ball load, and overall vehicle mass limits. While it might be tempting to push right up to those limits, it’s always safer to stay comfortably within them. Vehicle manufacturers often publish different ratings for different engine or transmission variants, so don’t assume all models in the same range have identical capabilities. For example, a diesel version may be able to tow more weight than a petrol version, and automatic gearboxes often behave differently under heavy loads compared to manuals.

Common Towing Terms

• Heavy Vehicle vs Light Vehicle Towing: Understanding the difference is critical for ensuring safe and legal compliance.
• Gross Trailer Weight (GTW): The combined weight of your trailer and everything in it.
• Tongue Weight (TW): The downward force the trailer places on your towball, usually 10% of the GTW.
• Tare: The vehicle weight without fuel.
• Kerb Weight: The vehicle weight with fuel, ready to drive, excluding passengers, and cargo.
• Gross Vehicle Mass (GVM): The maximum operating mass of the vehicle including fuel, passengers, and cargo.
• Gross Trailer Weight (GTW): The combined weight of your trailer and everything in it.
• Gross Combination Mass (GVM + GTW): The total combined weight of the fully loaded towing vehicle and fully loaded trailer.

In addition to weight limits, your trailer and tow vehicle combination must be able to stop within 7m from 30 km/h, and on open roads you are legally limited to a maximum towing speed of 90 km/h.

Choosing The Right Towbar

How To Measure Gross trailer weight (GTW)

This is the total weight of the fully loaded trailer.

The entire weight should be supported when determining the GTW. A commercial scale is the best means as found at testing and weigh-bridge stations. This method is shown in the picture to the right.

How To Measure Tongue weight (TW)

Tongue weight is the downward force exerted on the towball at the coupling.

For light trailers a normal bathroom scale, placed on a box to simulate the normal towbar height is suitable. If the weight is beyond the capacity of the household scale use the method pictured right and described below.

Place a household scale and block of same thickness three feet apart. Place a length of pipe on the scale and block as shown, then a beam between them. Zero the scale to account for the weight of the pipes and beam. Rest the trailer coupling on a stand on the beam one foot from the block. To obtain the tongue load multiply the result by three.

If the scales do not have the required capacity, space the block and scales four feet apart, place the trailer stand on the beam one foot from block and multiply the scale reading by four.

Note: The towbar’s tongue capability is clearly displayed on the towbar label.

Tip: Before towing, weigh your loaded trailer at a weighbridge to be sure you’re within the limits of safe towing.