Trailer Lingo For The Novice Buyer

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When you first buy a trailer, the jargon can be daunting. Do you know your VIN from your VP. And do you really need weight distribution bars?

Aggregate Trailer Mass (ATM)

The total laden weight of the trailer, including the weight of whatever you’re carrying and the weight imposed on the tow ball by the trailer’s coupling. This means that the ATM will be the GTM (see below) plus the weight on the tow ball.

Box Trailer

You’ll hear this everywhere – it has become a generic term for any trailer with sides.


The coupling is the link that joins your trailer to the towing vehicle. There are different types depending on the weight you’re hauling and whether you want to take it adventuring off-road or just to the local tip.

Gross Trailer Mass (GTM)

This tells you how much weight the trailer can carry fully loaded. Unless you’re towing heavy cargo, all you really need to know when you buy a trailer is that if its GTM is 750kg or less, it is not required to have brakes.

Open Or Enclosed Trailer

As the terms suggest, this refers to whether the trailer is open or covered. You might like to know which is best for your needs.

Single Axle

This trailer has one axle attached either via the springs or directly onto the trailer bed with clamps or supporting hardware. It’s light, easy to tow and generally cheaper than a tandem.

Tare Mass

The empty weight of the trailer will be stamped on it by the manufacturer.

Tandem Axle/ Dual Axle

Tandem trailers have two axles placed in close proximity to help disperse the weight load of the cargo. They tend to be designed to carry heavier loads, be more stable and have better suspension than single axles.

Tie-down Points

Any load you carry will need to be securely tied down. Built-in tie-down points recessed into the trailer floor can be a bonus if you regularly haul heavy items such as motorbikes.

Weight Distribution Hitch

Also called a ‘level ride’ or ‘load leveller’, this prevents your car from sagging when the trailer is connected by evenly distributing weight across all wheels of the towing vehicle and trailer.

Weight Rating

Each trailer will have a maximum weight it can carry legally. If you’re confused by acronyms such as GTW, GTM or ATM, this article about trailer towing capacity explains what they all mean.

Vehicle Plate (VP)

All new trailers built since August 1989 are required to have a vehicle plate (VP) listing the trailer’s ATM, GTM and tare weight.


All trailers must be identified by means of a 17-character vehicle identification number (VIN). Some states require the VIN be stamped on the trailer.

Now that you know some of the jargon, you won’t feel like the new kid on the block when buying a trailer.

Want to know the difference between a pig trailer, dog trailer, semi-trailer and box trailer? Get the lingo right with our easy guide.


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