7 Trailer Safety Chain NZ Requirements & Where To Buy

Every trip with a trailer or boat in tow carries a simple responsibility: keeping your load safely attached to your vehicle. In New Zealand, this goes beyond common sense—it’s a legal requirement, and failing to get it right can lead to a Warrant of Fitness (WoF) refusal or, much worse, a dangerous accident on the road. The rules aren’t arbitrary; they’re set out in the Land Transport Rule: Vehicle Standards Compliance 2002 and the NZS5467 standard, both designed to protect everyone on our roads.

But not all trailer safety chains are created equal, and it’s surprisingly easy to fall foul of the regulations if you don’t know exactly what’s required. Whether you’re a weekend boatie, a tradie, or you simply haul gear for the bach, understanding the seven key safety chain requirements could make all the difference—both for your peace of mind and your legal compliance. This guide unpacks those seven essentials in plain English, from breaking strength to chain markings, and explains how the rules change as your trailer gets heavier.

Ready to get it right? We’ll also point you to trusted New Zealand suppliers—starting with Action Outdoors—so you can source fully compliant chains and hit the road with confidence.

1. Safety Chain Minimum Breaking Strength Requirement

One of the simplest yet most critical rules for trailer safety chains in New Zealand is that each chain must have a minimum breaking strength at least twice the trailer’s Maximum Towed Mass (MTM). In plain terms, if your trailer’s MTM is 1,500 kg, you cannot use chains rated below 3,000 kg. This requirement ensures that even if the coupling fails, the chains retain enough reserve strength to hold the trailer in tow and prevent it from running loose.

1.1 What “2× Maximum Towed Mass” Means in Practice

Before you start shopping, it helps to understand the terminology:

• Maximum Towed Mass (MTM): The heaviest weight your trailer is designed to carry when fully laden, as specified by the manufacturer.
• Breaking Strength: The force at which the chain will fracture when tested under controlled conditions.

Here’s a quick calculation example:

1,500 kg MTM × 2 = 3,000 kg minimum breaking strength

And a few common MTM categories with their corresponding chain ratings:

• 1,000 kg MTM → minimum 2,000 kg chain
• 1,500 kg MTM → minimum 3,000 kg chain
• 2,000 kg MTM → minimum 4,000 kg chain
• 2,500 kg MTM → minimum 5,000 kg chain

Always round up to the next standard chain rating if your trailer falls between these values.

1.2 Reference to NZTA Land Transport Rule Requirements

The legal basis for this rule comes directly from the Land Transport Rule: Vehicle Standards Compliance 2002. As it states:

“Safety connection(s) shall have a minimum breaking strength equal to 2 times the maximum towed mass.”

For the full text, see the Land Transport Rule: Vehicle Standards Compliance 2002.

1.3 Real-World Importance of Correct Breaking Strength

Imagine towing a small camper on State Highway 1 with chains rated for only 1.5 times your MTM. If the coupling lets go, those under-strength chains could snap instantly, leaving your camper barreling down the road. Aside from the obvious danger to other road users, you’d face:

• WoF refusal: Your trailer won’t pass its next inspection until you fit compliant chains.
• Fines and liability: If a detached trailer causes damage or injury, you can be held legally responsible.
• Insurance complications: Policies often exclude claims arising from non-compliant equipment.

Ensuring your chains meet the 2× requirement is a small investment that pays huge dividends in safety and legal peace of mind.

2. Separate Attachment Points Requirement

Fitting your safety chains through the same fastenings as the coupling might seem simpler, but it completely defeats their purpose. If a coupling fails and the attachment shares that point, both will let go simultaneously. To ensure true redundancy, chains must be fixed to the trailer frame at points wholly independent of the tow coupling. This separation means that, in the event of coupling failure, the chains remain engaged and the trailer stays in line behind your vehicle.

2.1 Statutory Detail: Independent Attachments

The Land Transport Rule spells it out clearly:
“The attachment of the safety connection(s) to both the towbar and drawbar shall be separate from the coupling and its fastenings.”

In practice, this means your chains should loop through dedicated eyelets or lugs welded or bolted onto the drawbar and chassis—never simply hung off the coupling plate or towball mounting bolts. By isolating these points of connection, you add an extra layer of security. Should the main coupling give way under stress, the safety chains continue to bear the load, keeping the trailer in tow and preventing a runaway hazard.

2.2 Bolt-On vs Weld-On Clevis Assemblies

There are two common methods for providing these independent attachment points: bolt-on clevis assemblies and weld-on clevis assemblies. Bolt-on fittings use high-strength bolts and plates to create a removable lug, while weld-on clevises are permanently fused to the frame. Both have pros and cons:

• Bolt-on: Easier to replace or upgrade without specialised workshop gear; avoids heat distortion of the trailer’s metalwork.
• Weld-on: Offers a lower profile and generally a clean factory finish; no chance of bolts loosening over time.

Whichever method you choose, make sure it meets the strength requirements of the chain itself. You can find more on these styles in discussions of how attachment styles affect safety on blogs like this one from Laclede Chain.

2.3 Common Installation Mistakes and How to Avoid Them

Even when chains and clevises meet legal specs, poor installation can sideline your safety measures. Watch out for these common slip-ups:

• Attaching chains to the towball mount rather than a dedicated drawbar lug.
• Using shackles or bolts with a lower working load limit than the chain itself.
• Over-torquing or under-torquing shackle pins, leading to fatigue or slippage.
• Routing chains so they rub against sharp edges or chafe over time.

To avoid these pitfalls, follow a simple checklist at each fitment:

1. Verify each attachment point is separate from the coupling and rated to the chain’s breaking strength.
2. Inspect shackles and pins for matching grade markings—never mix 30-grade fittings with 70-grade chains.
3. Torque bolts and shackle pins to manufacturer guidelines, and re-check after the first 50 km of travel.
4. Give each chain a visual once-over before every trip, ensuring there’s no undue wear, twisting or contact with neighbouring components.

Proper installation isn’t just about ticking a box; it’s the difference between a secure tow and a critical failure. With these checks in place, your safety chains will be ready to do their job—even if the unexpected happens.

3. Attachment Point Strength Must Match Chain Capacity

Even the strongest chain is only as reliable as its weakest link—and in this case, that often means the fixing points and hardware. If shackles, brackets or clevis assemblies aren’t rated to at least the same breaking strength as your safety chain, they become the failure point in the event of an emergency. Ensuring every component in the safety chain assembly shares or exceeds the chain’s rated capacity is non-negotiable for both legal compliance and real-world security.

3.1 Requirement Overview

The NZS5467 standard is clear:
“The safety connection(s) attachments shall have a strength equal to, or greater than, the safety connection.”

If you fit a chain rated to 5,000 kg but use shackles or mounting brackets rated at only 3,000 kg, those fittings will yield first—exactly when you need maximum reserve strength. In practice this means:

• Every shackle pin, washer, clevis or bracket must carry the same grade marking as the chain.
• Hardware rated below the chain’s breaking strength effectively reduces your safety margin to the lowest-rated part.
• Mixing and matching components from different grades (for example, Grade 30 shackles with Grade 70 chain) is not just bad practice—it violates the intent of the Land Transport Rule and risks a Warrant of Fitness refusal.

3.2 Choosing High-Tensile Attachment Hardware

When selecting hardware, aim for components designed specifically for towing applications:

• Look for Grade 70 (G70) or higher D-shackles—these are heat-treated for high tensile strength and corrosion resistance.
• Choose clevis pins and mounting plates manufactured to the same grade; they should bear matching mill stamps or logos.
• Specify washers and nuts that accompany your shackles—avoiding generic or unknown-grade fittings ensures every element meets the chain’s rated capacity.
• Pay attention to finish: hot-dip galvanised or yellow chromate finishes add a layer of corrosion protection, particularly important in marine or coastal environments.

By standardising on a single high-strength grade across chain, shackles and brackets, you eliminate the guesswork and maintain full rated capacity under load.

3.3 Reference to AS/NZS 4177.1 Testing Methods

To guarantee your chain assembly performs as expected, refer to the testing protocols in AS/NZS 4177.1:2004. Appendix B of this standard outlines both static and dynamic tests for chain and associated hardware:

• Static testing confirms components hold well beyond their working load limit without permanent deformation.
• Dynamic testing simulates repeated tension cycles to uncover fatigue weaknesses over time.

While the full standard is available for purchase, you can review a summary of requirements and test methods here:
https://store.standards.org.au/product/as-4177-1-2004

Ensuring every element in your safety chain assembly is tested and rated to the same standard means you can tow with genuine confidence—knowing there’s no weak link waiting to give way.

4. Correct Chain Length & Positioning

Even a fully rated chain can fail to do its job if it’s the wrong length or routed poorly. Chains that drag on the ground wear prematurely, while those that are too short can bind or even lift the drawbar during turns. Getting the length and routing right ensures your chains stay clear of the road surface, yet still catch the trailer tongue if the coupling fails.

4.1 Avoiding Dragging vs Providing Sufficient Slack

A good rule of thumb is that safety chains should hang from the trailer tongue in a straight line without touching the ground. Too much slack increases the risk of chains dragging, which leads to accelerated corrosion and could snag on obstacles. Conversely, chains that are too tight can pull up the drawbar or twist around components during tight turns.

To strike the right balance:

• Measure the distance from each attachment point on the drawbar to the tow coupling.
• Add enough chain length to allow for a full lock-to-lock turn without binding.
• Subtract a small amount—usually 50–100 mm—to keep the chains off the road under normal load.

For a popular option, see our 8 mm trailer safety chain rated, which offers the right mix of length and strength for most light-duty trailers.

4.2 Positioning Near Centreline to Control Direction

The NZS5467 standard specifies:
“Fitted as close as practicable to the longitudinal centre line and of such length that, in the event of coupling failure, it will prevent the drawbar hitting the ground as well as controlling the direction of the trailer to follow the towing vehicle.”

Positioning chains close to the centreline minimises lateral swing if the coupling lets go. Ideally, chains should attach to lugs aligned within 100 mm of the centreline, forming a symmetrical ‘V’ beneath the drawbar. This alignment not only keeps the trailer tracking straight but also reduces side-to-side angle on the chains themselves, extending their working life.

(A diagram comparing correct V-shaped routing versus chains set too wide or too low would illustrate this clearly.)

4.3 Practical Installation Tips

To maintain correct positioning and prevent chafing:

• Fit chain guides or clips under the drawbar to hold the chains neatly in place when untensioned.
• Ensure shackles sit flush in their clevises; a tilted shackle can allow the chain to rub against the frame.
• After installation, perform a full lock-to-lock turning test—observe any contact with the vehicle or trailer body and adjust chain length or mounting height as needed.

Before each trip, glance under the drawbar to confirm chains are still seated in their guides and free of kinks. For those needing a pre-measured option, consider our 8 mm × 580 mm chain (14 links) for consistent performance and easy installation. Regular checks and minor adjustments will keep your safety chains ready to deliver maximum protection if the unexpected happens.

5. Welding Chains Is Not Permitted

It might be tempting to repair a worn or broken link by welding it back together, especially out in the field. However, as soon as heat is applied, the chain’s carefully engineered properties are irrevocably altered. Welding compromises the metal’s heat treatment, reducing tensile strength and making the chain unpredictable under load. For safety chains—your last line of defence if a coupling fails—this risk simply isn’t worth taking.

5.1 Regulatory Basis

NZS5467 makes it crystal clear:
“Welding of chain is not acceptable.”

This isn’t a suggestion—it’s a firm requirement under New Zealand’s trailer safety regulations. A welded splice can create a weak point that fails well below the chain’s original rated breaking strength. In the event of a coupling failure, a welded link could give way first, turning a serious emergency into a disaster.

5.2 Approved Mechanical Fittings

Instead of welding, always use purpose-built hardware to join or repair your safety chain assembly. Approved fittings include:

• D-shackles and bow shackles with pins rated to match—or exceed—your chain’s breaking strength (for instance, Grade 70).
• Clevis pins and mounting plates sized to suit your chain diameter, with mill-stamped grade marks.
• Safety chain kits that include pre-cut chain lengths, matching shackles and washers, all compliant with NZS5467.

These components are designed, tested and marked to retain full chain capacity. For example, our G70 D-shackle sets make fitting or replacing faulty links straightforward—no welding required.

5.3 Inspection Pointers to Spot Weld Splices

When you’re checking your chains, watch for tell-tale signs of unauthorised repairs:

• Uneven surfaces or splatter: A welded joint often appears rough or irregular, whereas factory-made links are smooth and uniform.
• Discoloured metal: Welding can leave heat-affected zones that stain or darken the steel near the splice.
• Inconsistent finish: A galvanised or chromate-coated chain should have even coverage; look out for bare steel or patchy areas around any suspected weld.

If you discover a welded link, retire the entire chain at once—even a single compromised link voids the chain’s rated capacity. Replace it with a new, fully compliant assembly that relies solely on mechanical fittings such as pre-cut chains (for example, an 8 mm × 500 mm chain with 12 links). That way, you can be sure your safety chains will perform exactly as designed when you need them most.

6. Mandatory Chain Markings & Rating Identification

Even the toughest chain can’t prove its worth if you can’t verify its rating. New Zealand’s NZS5467 standard demands that every safety chain—and every piece of associated hardware—carries clear, indelible markings. These stamps show you the chain’s grade, working load limit or minimum breaking strength, and the manufacturer’s identification. Without them, you’re essentially towing blind.

6.1 What Markings to Look For

When shopping or inspecting your chains and shackles, keep an eye out for:

• Grade stamp (for example, G70 or Grade 70)
• Minimum Breaking Strength (MBS) or Working Load Limit (WLL) in kilograms or tonnes (e.g. MBS 5000 kg)
• Manufacturer’s logo or three-letter mill code
• Batch or heat code for traceability

These markings should be permanently pressed into the metal, not simply painted or etched on. If you can scrub it off with a wire brush, it’s not compliant.

6.2 Verifying Authenticity & Compliance

Interpreting those tiny stamps can be confusing at first, but it pays to be thorough:

• Consult the chain manufacturer’s load-test chart to match the grade stamp with its rated capacity.
• Cross-check the WLL against your trailer’s 2× MTM requirement—if the WLL isn’t at least double your MTM, swap it out.
• Look for third-party certification marks (for example, a “TÜV” or “CE” logo) on imported hardware—this shows the batch was independently tested.
• When in doubt, request specification sheets or a compliance declaration from your supplier. Reputable retailers like Action Outdoors should have these on hand.

Having the right paperwork and knowing how to read the codes means you won’t be caught out at your next WoF inspection.

6.3 Differentiating Between Chain Grades

Chains come in various grades—each designed for different applications:

• Grade 30: Often used for general-purpose lifting and binding; not recommended for towing.
• Grade 70 (Transport Grade): Heat-treated for high tensile strength and commonly used for trailer safety chains.
• Grade 80/100: Primarily used in overhead lifting and rigging; overkill for most towing needs and typically more expensive.

Grade 70 strikes the best balance for towing: it offers the corrosion resistance and strength you need without the cost premium of lifting-grade chain. If your chains aren’t clearly marked G70, they probably belong on the binder, not the towbar.

7. Weight-Based Chain & Breakaway Brake Requirements

New Zealand’s trailer regulations recognise that heavier trailers pose greater risk if they detach. For lighter trailers, a safety chain alone is often enough backup. But once you cross certain weight thresholds, breakaway braking systems become mandatory. Below is a quick guide to how the rules change as your trailer’s Gross Laden Weight (GLW) increases.

7.1 Trailers up to 2,000 kg Gross Laden Weight

If your trailer’s GLW is 2,000 kg or less, you need at least one safety chain—provided it meets all the requirements we’ve covered so far. A breakaway brake kit is not mandatory for this weight class, though fitting one can add an extra layer of security. Many small boat trailers and light utility trailers fall into this bracket, so a single, compliant chain will keep you both legal and safe.

7.2 Trailers > 2,000 kg and < 2,500 kg: Twin Crossed Chains

Once your trailer exceeds 2,000 kg but stays under 2,500 kg GLW, the Land Transport Rule steps up the redundancy. You must use twin crossed chains crossed underneath the drawbar in an “X” formation, unless your trailer is equipped with a certified breakaway braking system. Crossing your chains means that if one lets go, the other still holds the tongue close to the centreline—minimising lateral swing. For a quick overview on why chains are crossed, see this short clip: Are you supposed to cross safety chains on a trailer?.

7.3 Trailers 2,500 kg to 3,500 kg: Breakaway Brake Mandatory

Heavier trailers—those from 2,500 kg up to 3,500 kg GLW—must be fitted with a breakaway braking system. In this category, safety chains become optional: the breakaway kit is your primary backup. These systems use a dedicated trailer-mounted battery and switch mechanism to apply the brakes if the coupling detaches, bringing the trailer to a controlled stop. In many situations, a reliable breakaway kit provides a level of safety beyond what even twin chains can offer, especially on steep descents or busy highways.

Whether you’re towing a light runabout or a large commercial trailer, matching your safety gear to the correct weight class keeps you compliant and dramatically reduces the risk of a runaway load. Always check your trailer’s plated GLW before deciding between single chain, twin chains or a breakaway brake system—and remember that nothing beats a professional fitment and regular maintenance.

8. Choosing, Installing & Maintaining Your Trailer Safety Chains

Selecting the right safety chains is only part of the story. Once you’ve chosen chains rated to match your trailer’s MTM, you need to fit them correctly and keep them in good nick. A well-chosen, properly installed and regularly inspected chain assembly will serve faithfully for years, protecting you from costly fines, failed WoFs and, most importantly, dangerous runaways.

8.1 Selecting the Right Size, Material & Finish

Choosing a chain means matching diameter, grade and protective finish to your towing needs:

• Chain diameter & grade

  • 8 mm Grade 70 is the most common size for trailers up to 2,000 kg GLW.
  • 10 mm Grade 70 suits heavier or commercial trailers, offering greater breaking strength.
  • Always verify the chain’s Minimum Breaking Strength stamp meets the 2× MTM rule.

• Material & corrosion protection

  • Hot-dip galvanised: Thick zinc layer resists rust in coastal or marine environments.
  • Yellow chromate passivation: Lighter finish with good corrosion resistance and a distinctive appearance.

• Pre-cut sets vs. metre-sold chain

  • If you prefer a ready-to-fit option, Action Outdoors’ 8 mm G70 Safety Chain Set (12 links) delivers the right length and matching D-shackle in one kit.
  • For custom lengths, our 8 mm trailer safety chain by the metre allows you to cut exactly to your drawbar dimensions.

8.2 Proper Installation Checklist

A systematic installation ensures every element of your chain assembly performs to its rating:

1. Mount attachment points

   • Fit bolt-on or weld-on clevis assemblies on each side of the drawbar, within 100 mm of the centreline.
   • Confirm they’re separate from coupling fastenings.

2. Cut or select correct chain length

   • Allow enough length for full lock-to-lock turns without binding.
   • Keep chains off the ground—chains should hang in a straight line under light tension.

3. Cross chains (if required)

   • For trailers 2,000–2,500 kg GLW, cross the chains beneath the drawbar in an ‘X’ to control lateral swing.

4. Fit matching D-shackles and washers

   • Use Grade 70 shackles rated at or above the chain’s MBS.
   • Torque shackle pins to the manufacturer’s specification (re-check after 50 km).

5. Perform a turning test

   • With the trailer hitched and ballast in place, turn full lock both ways.
   • Watch for chafing, binding or contact with the tow vehicle.

6. Record installation details

   • Note chain grade, fitting date and torque values in your maintenance log.

8.3 Routine Inspection & Maintenance Tips

Even top-quality chains need periodic checks. Make these inspections part of every trailer service:

• Visual condition of chain links

  • Look for nicks, deformation or corrosion pits.
  • Replace the entire chain if any link shows cracking or significant wear.

• Hardware integrity

  • Confirm shackles, clevises and pins carry matching grade marks and are free of rust.
  • Ensure nuts and pins remain torqued and haven’t loosened under vibration.

• Finish and protective coatings

  • Re-apply zinc spray or rust-inhibitor on exposed metal after chipping or flaking.
  • Coastal users should rinse salt off chains and fittings after each outing.

• Markings & traceability

  • Check that all stamps (e.g., G70, MBS value, manufacturer logo) are legible.
  • If markings have worn away, retire the chain and fit a new, fully marked assembly.

• Replacement interval

  • Even corrosion-resistant chains should be replaced every 5–7 years or sooner if used heavily in harsh conditions.
  • Always swap out chains in matched pairs to maintain equal load sharing.

By choosing the correct size and finish, following a structured installation process and keeping on top of maintenance, your trailer safety chains will remain a reliable safeguard for every tow. Ready to secure your load? Browse the full range of NZTA-compliant trailer safety chains at Action Outdoors today.

9. Where to Buy Compliant Trailer Safety Chains in New Zealand

Having covered the technical must-haves, here are six trusted New Zealand suppliers offering NZTA-compliant safety chains, from pre-cut kits to bespoke lengths—each backed by local stock and expert support.

9.1 Action Outdoors (Auckland & Online)

Action Outdoors is your one-stop shop, whether you visit the showroom in Auckland or order online for fast NZ shipping. They stock an 8 mm trailer safety chain rated 2.5 tonnes sold by the metre, plus a handy 8 mm G70 safety chain set (12 links) complete with Grade 70 D-shackle. All chains carry indelible NZS5467 markings, and you’ll get expert advice on installation and compliance.

9.2 Trailparts – Safety Chain Kits & Parts

Trailparts offers a comprehensive range of pre-cut safety chain kits, D-shackles and mounting hardware, all compliant with NZS5467:1993. Browse their safety chain kits & parts for ready-to-fit lengths, high-tensile shackles and industry-tested clevis assemblies.

9.3 Transquip – 2.5 Tonne Rated Long-Link Chain

For exact lengths on demand, Transquip’s 2.5 tonne rated safety chain is cut to order at any branch. Each metre is hot-dip galvanised and manufactured to NZS5467 standards, making it ideal for tradespeople and fleet maintenance.

9.4 Trojan – Stainless & Galvanised Chains & Shackles

Trojan stocks an extensive selection of stainless steel and galvanised safety chains, shackles and fittings. Their Safety Chains & Shackles range includes captive-link and insert designs, perfect for marine and coastal applications that demand superior corrosion resistance.

9.5 TWL NZ – Light Trailer Accessories

TWL NZ specialises in light trailer parts, offering both standard and heavy-duty safety chains in various link sizes. Check out their light trailer accessories – safety chains for budget-friendly, compliant solutions suited to small boat trailers and utility rigs.

9.6 Cookes – Long Link Trailer Safety Chain

Cookes supplies long-link trailer safety chain in 8 mm or 10 mm diameters, finished in gold-zinc passivation or hot-dip galvanisation. Their long link trailer safety chain delivers clear grade markings and excellent durability, meeting NZS5467 requirements for both recreational and professional use.

10. Keep Your Trailer Safe & Compliant

Sticking to these seven key requirements isn’t just about ticking a box at your next Warrant of Fitness—it’s about making sure your trailer behaves exactly as intended even when things go wrong. From choosing chains with at least twice your trailer’s Maximum Towed Mass, to fitting them on independent, equally rated attachment points, each rule builds on the next to form a reliable safety net.

Correct chain length and routing keep links clear of the road while still catching your drawbar if the coupling lets go. Matching your chain’s breaking strength with Grade 70 shackles and fittings means there’s no weak link in the system. And by rejecting any welded repairs, insisting on clear NZS5467 markings and following the weight-based rules for single, crossed or breakaway chains, you’ll meet both legal standards and real-world demands.

Regular checks—looking for worn links, loose shackles, faded markings or corroded coatings—ensure that you catch issues long before they become critical. A quick turning test after installation, a torque check on shackle pins and a rinse down in marine environments all go a long way towards keeping your trailer on the straight and narrow.

Whether you’re towing a small boat, a heavy camper or gear for a commercial load, integrating these practices into your trailer routine pays dividends in safety, compliance and peace of mind. Ready to secure your load? Browse our full range of NZTA-compliant trailer safety chains at Action Outdoors today.