Guide
Caravan weights explained: MTPLM, MIRO, payload and the 85% rule
Updated
Caravan brochures speak their own language of acronyms. Four of them decide whether the van behind you is legal and stable.
The four numbers that matter
- MTPLM
- Maximum technically permissible laden mass: the caravan's plated maximum, van plus everything in it. This is the trailer MAM for licence and towing-limit purposes, whatever the van actually weighs on the day.
- MIRO
- Mass in running order: the caravan as it leaves the factory, typically including essentials like a gas bottle allowance. The empty-ish baseline.
- Payload
- MTPLM minus MIRO: what you're allowed to add. Awnings, water, bedding and a full toilet cassette eat it fast; motor movers alone can take 30 to 40kg.
- Noseweight
- The downward load on the towball. Keep it within both the car's towball limit and the hitch limit, and aim for roughly 5 to 7% of the caravan's actual laden weight for stability.
Matching a caravan to your car
- Legal test: the caravan's MTPLM must not exceed your car's braked towing limit, and the outfit must stay within the car's gross train weight. That's the law side, the checker covers it.
- Stability rule of thumb: caravanners commonly aim to keep the loaded caravan at or below 85% of the car's kerbweight, and never above 100%. This is a rule of thumb with no basis in law, and we could not find an official source that publishes it, so treat it as a comfort guide rather than a limit.
- Licence test: with MTPLM at or under 3,500kg, a full category B licence covers effectively every touring caravan sold in the UK.
Worked example
A car with a 1,500kg braked towing limit and 1,600kg kerbweight, towing a caravan with MTPLM 1,400kg: legal (1,400 is under 1,500), but at 87.5% of kerbweight it sits just above the 85% rule of thumb, fine for an experienced tower, worth thinking about for a first season. The same car with a 1,300kg MTPLM van sits at 81%, inside the guidance with payload to spare.
Weigh the loaded outfit at a public weighbridge once a season. Plated limits are what the law checks, but the scales tell you what you're actually towing.