MRO and MTPLM typically apply to caravans. MRO stands for Mass in Running Order, while MTPLM stands for Maximum Technically Permissable Laden Mass. You can find the label for MRO and MTPLM on a panel—typically on the side of the caravan—or in the handbook.
The MRO is the weight of the caravan as it is, or more succinctly, completely unladen. MTPLM is how much weight on top of the MRO that the caravan can carry down the road safely or, how much you can load up in the caravan without overdoing it.
The real question should have been, who in the world came up with those acronyms and why? But that’s neither here nor there as it is what it is. The MRO is essentially the caravan’s weight and it will be listed on the panel and/or in the caravan’s handbook, along with the MTPLM.
Are There Other Weight Terms?
Of course, there are, because you know that if a bunch of engineers could sit around and come up with something as unnecessarily complicated as MTPLM, they can also come up with a varying plethora of terminology.
- Ex Works Weight
- Essential Habitation Equipment Payload
- Optional Equipment Payload
- User Payload
- Personal Effects Payload
- Kerb Weight
- Nose Weight
We’ll start by dealing with what exactly MIRO is. MIRO is simply, MRO. Somebody decided somewhere along the line to subtract the “I” and make it MRO or maybe, it was the other way around. Who knows? But MIRO and MRO are the same things.
Ex Works Weight is the weight of the caravan when it departs the manufacturing facility that put it together. This is essentially the same exact thing as MRO or MIRO, so if you’re confused, we don’t blame you. There is a 3% to 5% allowance for manufacturer variations, however.
Essential Habitation Equipment Payload this is the added weight of everything that is included in the caravan that is deemed essential for habitation, which includes:
- Water Heater
- Gas Heater
- Gas Cylinders
- Air conditioning and heating systems
Anything that you would consider essential in order to inhabit the caravan is most likely on the list for Essential Habitation Equipment Payload.
Optional Equipment Payload is like the trim differences in a vehicle. It’s all of the additional perks, equipment, enhancements, add-ons, and extras that the manufacturer adds to the baseline caravan. All of that “optional equipment” has its own weight category and is listed when the manufacturer delivers the caravan.
User Payload is similar to how GVWR (Gross Vehicle Weight Ratio) is determined for big rigs (18-wheelers). It’s the difference in weight between the MTPLM and MRO. That difference accounts for what the “user” (or owner) adds to the caravan after purchase.
If the MRO is 9,000lbs and you add an additional 1,500lbs in materials, equipment, and supplies, the MTPLM is now 10,500lbs while the user payload is nothing more than 1,500lbs of stuff you added.
Personal Effects Payload (PEP) sounds like it would simply be what it looks like. However, this is one of the more complicated calculations of the bunch. The formula for determining PEP is PEP = 10L + 10N = 50kg. L stands for the length of the caravan and N stands for the number of berths.
If you have a 5.5-meter long caravan and it has 5 berths, then you will have a PEP of 155kg. It’s a nice little bit of algebra to determine your PEP but not too bad.
Kerb Weight is the total weight of the vehicle portion of the caravan and it excludes the caravan as a whole. It’s essentially just the vehicle portion and nothing more or less.
Nose Weight is how much the caravan weighs directly at the front or (nose) of the car. It’s the exact section where the car turns to the caravan. It can often be confused for the kerb weight and rightfully so because they’re basically the exact same thing (in terms of weight).
That’s it insofar as weight is concerned when it comes to caravans. You probably never dreamed that there would be that many different weight classifications for what amounts to a van/camper combination.
In fact, most of the weights are never routinely used, nor will you, as the driver, ever really use any of them. But, if you ever wanted to know about the weight classifications for a caravan well, there you go.
All Things Considered
Most all of the different weight classifications have a lot in common with the standard MRO or MTPLM. However many of the classifications, only the MRO and the MTPLM are going to label on your caravan in most cases.
All you really have to remember is that the MRO is the weight of the caravan and the MTPLM is the amount of weight that the caravan can carry, in terms of what gets added to it along the way.