Mass in Running Order (MiRO)
Mass in running order is the mass of the vehicle with its factory standard equipment, ready for use but without personal belongings. It is the starting point of the load capacity calculation. The figure given by the manufacturer is nominal; because of optional equipment and production tolerance the real mass can come out above this figure.
What the MiRO definition covers can vary by manufacturer and by regulation; it generally covers standard equipment and basic operating fluids and does not cover personal belongings. That is why, when comparing the MiRO figures of two different RVs, you have to look at what has been included.
- Being nominal: the catalogue value is given with a certain tolerance; two examples of the same model may not have the same mass.
- Options: extra equipment chosen at the factory raises the MiRO and narrows the load allowance.
- Verification: taking your vehicle empty over a weighbridge is more accurate than trusting the catalogue.
Systems fitted afterwards, such as a levelling set, affect not the MiRO but the usable load allowance; technically the added mass comes off the payload figure. When doing capacity planning the practical route is this: weigh the vehicle in its real empty state, then subtract it from the maximum laden mass; the number left is the real allowance for your belongings and the equipment to be added.
The context in which this term is used: RV automatic levelling guide