ADR, Tow-Carrier Claims & the Real Risks

Why “3.5T Rated” Hitch Carriers Are Often Dangerous Hype

The Wild West of Hitch-Mounted Cargo Carriers

There’s been a surge of bold claims lately — “ADR certified to 3.5 tonnes!” — on hitch-mounted spare, cargo, and fuel carriers that plug straight into a vehicle’s towbar.

Sounds impressive… until you look closer at the actual limits set by ADR 62/02, your vehicle’s down-ball rating, and how leverage, dynamic loads, and fatigue all interact.

At Mirack Products, we design, test, and manufacture in Australia — and our reputation is built on transparency: real data, real testing, and real safety.

Want to know our honest takeaway? If your hitch-mounted carrier and cargo weigh over 100 kg combined, you simply cannot tow 3.5T safely or legally.

Real Incidents That Prove the Risks of Overloading

Unfortunately, the dangers of pushing towing limits aren’t just theory — they’ve played out on Australian roads many times. Real-world incidents show what can happen when vehicles, tow systems, or accessories are used beyond their safe or certified capacities.

Fatal Overload Case in NSW (Walcha, 2019):

A driver towing a caravan that was allegedly overweight was involved in a fatal crash.
Police measured the wreckage and charged the driver for “towed vehicle weight exceeding the capacity of the towing attachment.”

Down-Ball Math in Practice

Let’s take a few real customer examples from the last few years. 3.5T rated vehicles, and smaller builds like the Subaru Outback and VW Touareg.

Toyota LandCruiser 300

Fitted with our GEN5 Dual Swinging Hitch Carrier, the vehicle having a factory down-ball limit of 350 kg. 

Now lets calculate:
• GEN5 Dual Swing Carrier weight ≈ 55 kg
• Cargo (tyre + fuel + brackets) ≈ 90 – 100 kg

That’s already around 150 kg before you hitch a trailer. 350 kg − 150 kg = ≈ 200 kg usable down-ball remaining. Since a trailer’s tongue weight is roughly 10 % of its mass, that equates to a 2 tonne trailer in perfect conditions.

Ford Everest

Fitted with our GEN4 Swinging Spare Wheel Carrier, the vehicle having a factory down-ball limit of 350 kg. 

Now lets calculate:
• GEN4 Swinging Carrier weight ≈ 30 kg
• Cargo (tyre + folding table) ≈ 50 – 60 kg

That’s already close to 100 kg before you hitch a trailer. 350 kg − 100 kg = ≈ 250 kg usable down-ball remaining. Since a trailer’s tongue weight is roughly 10 % of its mass, that equates to a 2.5 tonne trailer in perfect conditions with the carrier fully loaded. We would still impose a 2T max rating on this configuration - to take into account the extended tongue length and safety factor considerations.

Subaru Outback

Fitted with our GEN4 Swinging Spare Wheel Carrier, the vehicle having a factory down-ball limit of 200 kg. 

Now lets calculate:
• GEN4 Swinging Carrier weight ≈ 30 kg
• Cargo (tyre + folding table) ≈ 50 – 60 kg

That’s already close to 100 kg before you hitch a trailer. 200 kg − 100 kg = ≈ 100 kg usable down-ball remaining. Since a trailer’s tongue weight is roughly 10 % of its mass, that equates to a 1 tonne trailer in perfect conditions with the carrier fully loaded.

Add in bumps, sway, braking, and fatigue, and that margin disappears fast.
That’s why we rate our hitch carriers at 2T for through-towing — not 3.5T on paper.

Leverage and Moment Arm

As your carrier extends further behind the vehicle, it multiplies the torque on the hitch.
Every extra centimetre of offset means more stress on the towbar mounts and the vehicle chassis.

A 100 mm increase in extension can add hundreds of newton-metres of torque at the coupling.

Even if your load hasn’t changed in weight, the effective force on your mounts increases — and fatigue happens faster.

Tip: keep your setup as close to the towbar face as possible and inspect your hardware regularly.

Safe-Use Checklist

Before you head out, make sure your setup passes this quick audit:

✅ Weigh the carrier and subtract it from your vehicle’s down-ball limit.
✅ Include real cargo mass (tyre, fuel, brackets, etc).
✅ Remember that longer arms mean greater torque at the hitch.
✅ Leave margin for bumps, sway, fatigue, and shock loads.
✅ Stay within GVM / GCM / axle load limits.
✅ If towing more than 2T with rear cargo, use a chassis-mounted rear bar.
✅ Always demand documentation for any “3.5T ADR” claim before you purchase.

Our Philosophy: Safety Before Hype

Mirack’s 2T through-towing rating isn’t a marketing tactic — it’s grounded in physics, math, and real-world testing. In the market for one of these systems and considering your options? Try showing these calculations to anybody claiming 3.5T through-towing while using a loaded hitch carrier. Make sure you are buying the safest possible option for your vehicle.

We design for safety and longevity, not spec-sheet bragging rights.
When you’re towing thousands of kilos behind your vehicle, honesty matters more than hype. If you plan to tow more than 2T while carrying rear cargo, the correct solution is a chassis-mounted rear bar.

© 2025 Mirack Products — Engineered & Manufactured in Australia.