Do you find yourself confused by some of the expressions used about motorhomes? We’re on hand to help, as we provide simple definitions for some of the important terms you need to know…


Often seen by many as the most luxurious type of motorhome, these models are built from a chassis cowl up. Their bespoke cab offers lots of space, but driving one can feel slightly different at first. You can find out more about them by taking a look at our best A-class motorhome round-up.

An A-class motorhome

Grey water

Waste water from your tap or shower that is (usually) collected in an on-board tank.

GTW – Gross train weight

The maximum weight that the vehicle and any trailer combined can be, including the loads within each.


A type of campsite pitch that offers the user a solid base, rather than grass. Common materials are Tarmac or gravel.


Cable connection to the mains electrical supply at a campsite. Provides power to mains sockets and appliances.

Leisure battery

This 12V battery powers most of the essential kit within your motorhome’s accommodation area. It’s different to your base vehicle’s battery.

Low-profile coachbuilt

A type of motorhome with a limited amount of space in the Luton (the area above the cab seats). Unlike in the overcab coachbuilt, this zone is generally reserved for storage.

MAW – Maximum axle weights

As well as sticking to your vehicle MTPLM (see right), you’ll need to ensure you do not exceed the weight limit of its individual axles. Check these by using a weighbridge (

MiRO – Mass in running order

The motorhome’s basic weight, with all factory-fitted equipment, when it leaves the factory. Some manufacturers include the weight of a tank of fuel, water, a driver and more in this calculation; check with the firm to find out their exact definition.

MTPLM – Maximum technically permissible laden mass

The maximum your motorhome must weigh; this is defined by the vehicle manufacturer. You may also see this value described as MAM (maximum authorised mass) or GVW (gross vehicle weight). For this, and other important weights, check the data plate on your motorhome: it will likely be found in the engine bay or on a cab door frame. 

Overcab coachbuilt

An overcab coachbuilt

Overcab coachbuilts have a prominent Luton (the area over the cab), usually housing a double bed.


The total weight of items you may load into your motorhome (including passengers). This figure is calculated by subtracting the MiRO from the MTPLM.

PDI – Pre-delivery inspection

A final inspection and check of the ’van by the dealer before it is released to the buyer.

So now you’ve mastered the jargon, do you want to find out more about driving your motorhome? Then visit our Back to Basics – Driving category, where we’re sharing advice to perfect your driving skills on the road.

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