Why Are So Many Trailers Rated 1,990 kg?

Browse any Australian trailer catalogue and you'll notice the ratings are strangely specific. Plenty of trailers at 1,990 kg ATM. A few at 4,490 kg. Almost none at a round 2,000 or 4,500.

Those ten kilograms are deliberate. Each of those numbers sits just under a line in the regulations where the rules change, and a builder who stays below the line can build a simpler, cheaper trailer.

Independent guide based on VSB 1 and Queensland TMR guidance. Not legal or engineering advice. Confirm the figures on your trailer's compliance plate.

The cliff at 2,000 kg

Trailer braking requirements step up in stages, and the biggest step is at 2,000 kg ATM:

A breakaway system is the safety device that automatically applies the trailer's brakes if it comes off the tow ball, and it has to keep them applied for a set period. It needs a battery, a charging circuit, a trigger switch and wiring, all of which have to keep working years later.

So a tandem trailer rated at 1,990 kg can legally be built with brakes on one of its two axles and no breakaway system. Cross to 2,001 kg and it needs brakes on all four wheels plus the whole breakaway assembly. That is real money in parts and labour, on every single unit built.

Ten kilograms of rating, a meaningfully different trailer.

The other magic number: 4,490 kg

The same trick happens again at 4.5 tonnes, which is the line between a light vehicle and a heavy vehicle.

Above 4.5 t ATM a trailer stops being governed by ordinary state light-vehicle rules and falls under the Heavy Vehicle National Law, administered by the NHVR. That changes registration, the standards it's built and inspected to, and potentially what you need to tow it legally.

A 4,490 kg trailer stays on the light-vehicle side of that line. A 4,500 kg one does not.

And 750 kg, the original one

The most common rating of all is 750 kg, and it exists for exactly the same reason. It is the heaviest a trailer can be while needing no brakes whatsoever. It is also the standard "unbraked" towing figure quoted for most cars, so a 750 kg trailer is the largest thing a huge number of vehicles can legally tow without a brake controller.

That's why the classic Australian 6×4 and 7×5 box trailers cluster at 750 kg. It isn't what the steel can handle. It's where the rules change.

So is a 1,990 kg trailer a good buy?

Often yes, but go in with your eyes open. What you're really buying is a trailer built to sit just under a safety threshold.

In its favour:

• Genuinely cheaper, both to buy and later to maintain, because there's less braking hardware and no breakaway battery to replace.
• For most people the payload is ample. A tandem with roughly 700 kg tare still leaves you close to 1,300 kg.
• Fewer components that can fail an inspection or need servicing.

Worth thinking about:

• No breakaway protection. If the trailer ever separates from the tow ball, nothing applies its brakes. This is the one that matters, and it's the reason the threshold exists.
• Possibly brakes on one axle only. Not all 1,990 kg trailers are built this way, but they legally can be. Ask, and check the spec sheet rather than assuming.
• A hard ceiling. The ATM is stamped on the compliance plate and is the legal limit. You cannot decide later that 2,100 kg is "close enough". If your loads are creeping toward the limit, buy above the line instead of loading over it.

The honest rule of thumb: if your real loads sit comfortably under about 1,500 kg, a 1,990 kg trailer is sensible value. If you expect to run near the limit regularly, or you tow long distances at highway speed, the trailer above the line with all-wheel brakes and a breakaway system is the better buy for reasons that have nothing to do with the paperwork.

What this tells you when comparing trailers

Once you know the thresholds, some listings read differently:

1. A rating just under a threshold is a design decision, not a coincidence. It tells you what the builder chose to leave out.
2. Compare braking hardware, not just the ATM number. Two 1,990 kg trailers can be built very differently. One might have brakes on both axles anyway.
3. Check the tow vehicle against the same number. Your car needs a braked towing capacity of at least the trailer's ATM, and enough tow ball rating. See what size trailer you need.
4. The plate wins. Whatever a brochure claims, the ATM stamped on the compliance plate is the legal figure.

Our brake requirements guide covers each threshold in detail, and how to read a spec sheet decodes the rest of the listing.

Quick FAQ

Why is my trailer 1,990 kg and not 2,000 kg? Because over 2,000 kg ATM the law requires brakes on every wheel plus a breakaway system. Staying 10 kg under keeps the trailer simpler and cheaper to build.

What is a breakaway system? A battery-powered device that automatically applies the trailer's brakes if it detaches from the tow vehicle, and holds them on. It is mandatory above 2,000 kg ATM.

Is a 1,990 kg trailer safe? It is legal and built to standard. It simply has less braking equipment than one rated above 2,000 kg, and no breakaway protection. Whether that matters depends on how heavily and how far you tow.

Can I upgrade a 1,990 kg trailer to carry more? Not by loading it more. The ATM on the compliance plate is the legal limit. Raising a rating means engineering certification and, in practice, upgrading axles, brakes and coupling, which usually costs more than buying the right trailer.

Why are so many trailers exactly 750 kg? 750 kg is the heaviest a trailer can be with no brakes at all, and it matches the unbraked towing capacity of most cars.

What is 4,490 kg about? Above 4.5 tonnes a trailer becomes a heavy vehicle under national heavy vehicle law instead of state light-vehicle rules, which changes registration and standards. A 4,490 kg rating stays under that line.

Check where your load sits. Put your figures into the Compliance Auditor to see the ATM you actually need, whether brakes and a breakaway system are required, and what your tow vehicle has to be rated for. No sign-up.

Independent reference only. Confirm against your trailer's compliance plate and verify with TMR or a certified RPEQ engineer before purchasing, building or registering a trailer.