How To Weight Your Car and Caravan To Make Sure You’re Compliant

Getting your weight distribution wrong can land you in serious legal trouble, void your insurance, and put you and other road users at risk. Weighing your car and caravan combination properly isn’t just about compliance – it’s about understanding exactly what your rig can handle before you hit the road.

This guide walks you through the complete process of weighing your loaded car and caravan to ensure you’re operating within legal limits. We’ll cover everything from finding the right weighbridge to interpreting the results and making adjustments.

Step 1: Load Your Car and Caravan as You Would for Travel

Before you even think about finding a weighbridge, load everything exactly as you would for a typical Big Lap journey. This means full water tanks, food supplies, clothes, camping gear, tools, spare parts, and anything else you’d normally carry.

Don’t weigh with empty tanks and no gear – you need real-world numbers. Fill your water tanks to 95% (never completely full as water expands), load your pantry with your usual supplies, and pack all your camping equipment.

Include the weight of passengers too. If you typically travel with two people, have both people in the car during weighing. If you have pets, include them as well.

Step 2: Find a Suitable Weighbridge

You need a public weighbridge that can handle the length of your car and caravan combination. Most grain silos, quarries, and waste transfer stations have weighbridges available to the public, typically charging $15-30 per weigh.

Call ahead to confirm they can accommodate your combination length and ask about their operating hours. Some weighbridges close for lunch or have limited weekend hours.

Look for weighbridges that are at least 18 metres long if you’re running a typical 6-metre car with a 20-foot caravan. Shorter weighbridges might require multiple weighings to get accurate axle weights.

Step 3: Weigh Your Car Alone (Without Caravan)

Your first weigh should be the car by itself, loaded with everything except the caravan. Drive onto the weighbridge with just your tow vehicle, passengers, and all the gear you’d normally carry in the car.

This gives you your Gross Vehicle Mass (GVM) – the total weight of your loaded car. Make note of both the total weight and the individual axle weights if the weighbridge provides them.

The weighbridge operator will provide you with a ticket showing these weights. Keep this ticket as you’ll need these numbers for your calculations.

Step 4: Weigh the Complete Combination

Now couple up your caravan and drive the entire combination onto the weighbridge. Make sure both the car and caravan are completely on the weighing platform – no wheels hanging off the edges.

This weighing gives you your Gross Combination Mass (GCM) – the total weight of car plus caravan plus everything in both. Again, note both total weight and individual axle weights if available.

Some weighbridges can show you the weight distribution across different axles, which is valuable information for understanding how your caravan’s ball weight affects your car’s rear axle.

Step 5: Calculate Your Caravan Weights

With both weighings complete, you can now calculate your caravan’s actual weights:

Caravan Weight = GCM – Car Weight

This gives you the Gross Trailer Mass (GTM) of your caravan. You can also calculate ball weight if you have individual rear axle weights from both weighings:

Ball Weight = Rear Axle Weight (with caravan) – Rear Axle Weight (car alone)

Ball weight should typically be 10-15% of your caravan’s total weight for optimal stability and handling.

Step 6: Check Compliance Against Your Ratings

Now compare your actual weights against the maximum ratings found on your compliance plates:

Car Compliance:

• Actual GVM ≤ Maximum GVM (on your car’s compliance plate)
• Actual GCM ≤ Maximum GCM (also on your car’s compliance plate)
• Actual towing weight ≤ Maximum towing capacity

Caravan Compliance:

• Actual GTM ≤ Maximum GTM (on caravan’s compliance plate)
• Individual axle weights ≤ Maximum axle ratings

All these figures must be within limits. Even if your total weights are legal, exceeding individual axle limits is still a compliance breach.

Step 7: Make Adjustments if Needed

If you’re over any limits, you need to reduce weight or redistribute load before travelling. Start with the heaviest, least essential items.

Common weight reduction strategies include:

• Reducing water tank levels to 50-70% instead of full
• Removing duplicate tools or excessive spare parts
• Switching to lighter camping gear (titanium cookware, lightweight chairs)
• Carrying fewer clothes and doing laundry more frequently

For ball weight issues, move heavy items forward or backward in the caravan. Moving weight toward the axles reduces ball weight, while moving weight toward the front increases it.

After making changes, return to the weighbridge to confirm compliance. Some weighbridge operators offer discounted second weighings on the same day.

Common Weighing Mistakes to Avoid

Weighing with empty tanks: This gives you unrealistic numbers. Your compliance check must be based on loaded travelling weight, not empty weight.

Forgetting passengers: If two people normally travel in your setup, both should be present during weighing. Human weight affects your GVM calculations.

Ignoring individual axle limits: Your total weights might be legal while individual axles are overloaded. Always check axle-specific compliance.

Only weighing once: Weight distribution changes as you use water and consume food. Re-weigh after major gear changes or at least annually.

Assuming manufacturer weights are accurate: Caravan manufacturers often provide conservative weights. Your actual caravan might weigh 50-200kg more than the stated Tare weight.

Not accounting for accessories: Solar panels, awnings, bike racks, and other add-ons increase weight. Factor these into your calculations.