Towing Made Easy: Decode GVM, ATM & Tow Ball Weight for Horse Floats

Why Towing Knowledge Matters

Heading out with your horse or extra camping gear? Safety starts with understanding your towing setup. Overloading or poor weight distribution can cause sway, strain your vehicle, and even lead to accidents. This guide makes it simple to stay safe and legal under Australian standards.

Could it also be you just don't know and should know (aka the "She'll be right mate!"? Huge red flags peoples! Every time you go on the road, you are putting your horse(s), you and your family and other motorists at risk of serious injury or even death–recently highlighted with the major horse truck incident close to home here in the Canberra region (Sutton Forest).

🚙 Key Towing Terms Explained (Australian Standards)

1. GVM – Gross Vehicle Mass: The maximum weight your towing vehicle can carry, including passengers, fuel, gear, and the tow ball download. Set by the manufacturer.

2. ATM – Aggregate Trailer Mass: The total weight of your horse float when fully loaded (horses, tack, water, feed, camping gear etc.). This includes the float’s own weight (Tare) plus everything inside.

3. Tow Ball Mass (TBM): The vertical weight the float places on your vehicle’s tow ball. Ideally 10–15% of the float’s ATM for stability. Too much or too little can cause sway or strain.

4. GCM – Gross Combined Mass: The total allowable weight of your vehicle and float combined. Even if GVM and ATM are within limits, exceeding GCM is illegal and unsafe.

🧮 How to Work Out Your Setup

1. Check your vehicle’s handbook (or a quick Google search) for GVM, GCM, and tow ball rating.

2. Find your float’s compliance plate for Tare and ATM.

3. Add up your load: horses (~500–700kg each), gear, water, feed, people.

4. Use a weighbridge to confirm actual weights. Options in Canberra:

   1. Mitchell and Mugga Lane tips have weighbridges (it costs around $20-$30)

   2. Capital Weighing Service

5. Ensure tow ball mass is within spec (use a scale or consult your float manufacturer).

📊 Weight Distribution: Best Practices

Proper weight distribution keeps your rig stable and your horses safe. Here's what to aim for:

• Heavy items low and centered over the float axles.

• Avoid rear-heavy loading (causes sway, which can lead to jack-knifing/out of control scenarios).

• Balance left and right sides (especially with one horse).

• Keep tow ball mass within 10–15% of ATM.

• Secure all gear to prevent shifting during travel (big one is ensuring rakes/shovels are clipped down into place and not loose).

Here's a video which shows what can happen in good and bad towing weight distributions

✅ Quick Example: Calculating Your Setup

• Vehicle GVM: 3,200 kg

• Float ATM: 2,500 kg

• Tow Ball Mass: 250 kg (10% of ATM)

• Combined Load: 3,200 + 2,500 = 5,700 kg

• Check GCM: Must be ≥ 5,700 kg (from your vehicle specs)

If your GCM is only 5,500 kg, you’re overweight and need to reduce load or upgrade your vehicle.

Final Tips

• Use a weighbridge for accuracy.

• Check compliance plates and manufacturer specs.

• Always confirm tow ball rating and GCM before hitting the road.