Pre-Purchase RV or Trailer Weighing: The Smartest Step Before Buying

Buying a caravan, motorhome, horse float or trailer is exciting — but it can also be one of the most expensive mistakes if you don’t know the real weights before you commit.

Manufacturers’ brochures, dealer specs and compliance plates often don’t reflect real-world weight once options, accessories and fluids are added. It’s common to see differences of 200–600 kg between advertised tare and actual ready-to-tow weight.

One of the most common heartbreaking stories we hear at Clear Weight goes like this: You find the perfect caravan. The VIN plate says it has a Tare weight of 2,200kg and an ATM of 2,800kg. That leaves you a massive 600kg for luggage, water, and gear. Perfect!

But after you buy it, you weigh it, and realize the actual empty weight is 2,600kg because previous owners added solar panels, extra batteries, heavy toolboxes, and an annex. You are left with only 200kg of payload—which is legally unusable once you fill the water tanks.

Here’s the best approach — whether you’re buying privately or from a dealer.

 

Why Pre-Purchase Weighing Matters

Before looking at the process, it’s worth understanding what’s at stake:

• Overloading can void insurance

• Police and transport authorities actively enforce weight limits

• Handling, braking and stability are severely affected

• Suspension, tyres, bearings and chassis suffer accelerated wear

• Upgrading GVM or ATM after purchase can cost thousands

A 60-minute weighing session can prevent years of problems.

 

What a Proper Pre-Purchase Weight Check Should Include

A true assessment is more than just a single number from a weighbridge.

At Clear Weight, a professional pre-purchase check includes:

• Individual axle weights

• Tow ball weight (TBM)

• ATM / GTM comparison

• Load distribution analysis

• Tyre load compliance

• Margin to legal limits

• Compatibility with your tow vehicle’s GVM & GCM

• A written report explaining the results

This tells you not just what it weighs, but whether it will work safely and legally for you.

 

Buying From a Dealer – Best Practice

Dealers often rely on the manufacturer’s "average" Tare mass printed on the brochure or the compliance plate. However, this plate rarely accounts for dealer-fitted accessories like

• Air conditioners

• Batteries

• Solar systems

• Toolboxes

• Water tanks

• Gas bottles

• Awnings

• Accessories

The smartest approach:

1. Ask for a condition-of-sale weight clause

Request that the van or motorhome be weighed as delivered before final payment.

2. Weigh the Tare weight (no water or gas) after all accessories are fitted to get your true baseline.

Do not rely on brochure weights.

3. Use a mobile weighing service onsite

This is avoids moving unregistered vehicles and provides axle-by-axle accuracy.

4. Compare results to your tow vehicle limits

Not just ATM — but tow ball weight, rear axle loads, GVM and GCM.

5. Negotiate if needed

If the unit is overweight or unsuitable:

• Request accessory removal

• Re-specification

• Price adjustment

• Or walk away before signing

Dealers are increasingly familiar with this process — and reputable ones support it.

 

Buying Privately – Best Practice

Private purchases require more initiative, but the process is straightforward.

Step-by-step:

1. Confirm seller cooperation first

Most genuine sellers are happy to allow weighing.

2. Book a mobile weighing service to the seller’s location

Avoid public weighbridges, they are inconvenient to seller & they don’t show axle loads or ball weight.

3. Weigh it in its current configuration

This reflects how it has actually been used. In private sales, owners often leave their gear inside (cutlery, bedding, tools). When weighing, you must do a quick mental audit of what is inside to estimate the true empty weight.

4. Assess real payload remaining

Many used caravans already have most of their payload consumed.

5. Factor results into your offer price

If upgrades or changes are needed, you now have hard data.

 

Specific Considerations by Trailer Type

Different trailers hide weight in different places. Here is what to watch for during your Clear Weight pre-purchase inspection:

Caravans & Camper Trailers

• The Water Trap: Ask the seller if the tanks are full. 200L of water is 200kg. If you weigh it "wet" but think it's "dry," your calculations will be wrong.

• Hidden Mods: Look for extra batteries, grey water tanks, tool boxes and bike racks. These add up fast.

Horse Floats

• The Fit-Out Factor: Manufacturer weights often exclude the rubber matting, dividers, and chest bars. These are heavy steel and rubber items! A "2-horse float" might legally only carry one large horse once you account for the true weight of the build.

• Living Quarters: If the float has a kitchenette or tack box added post-factory, the original VIN plate is useless.

Boat Trailers

• The Combo Deal: You are rarely weighing just the trailer; you are weighing the Hull + Motor + Trailer.

• Fuel & Gear: A 200L underfloor fuel tank adds roughly 150kg. Is the tank full? Are the life jackets, anchors, and fishing gear inside?

• Galvanized Steel: Old boat trailers are heavy. If the trailer has been repaired or reinforced with extra steel over the years, it may now exceed your car’s towing capacity.

Common Traps Buyers Fall Into

• Trusting brochure tare weights

• Assuming “new means compliant”

• Ignoring tow ball weight

• Not checking axle ratings

• Forgetting vehicle GVM & rear axle limits

• Believing “it tows fine” means it’s legal

• Assuming as the ATM is well below your tow vehicles limit it’s OK

We regularly assess rigs that are technically illegal but feel normal to tow.

Why Mobile Weighing Is the Best Option

Mobile weighing provides:

• Real-world loaded measurements

• Axle-by-axle accuracy

• Tow ball weight data

• Compatibility with your tow vehicle’s GVM & GCM

• On-the-spot education

• Written compliance reports

• No need to move unregistered units

• No guesswork

It turns a risky purchase into an informed decision.

Final Thoughts

If you’re spending:

• $20,000…

• $80,000…

• or $150,000+

on a caravan, motorhome, horse float or trailer…

A pre-purchase weight assessment is one of the cheapest forms of insurance you can buy.

It protects:

• Your safety

• Your legal compliance

• Your insurance coverage

• Your tow vehicle

• Your long-term ownership costs

And most importantly — it ensures what you’re buying is actually fit for purpose.