MRO: What it means and why it matters
MRO (Mass in Running Order) is the older term for the unladen weight of a leisure vehicle. It has been largely replaced by MiRO for caravans, but you may still see it on older spec sheets.
MRO was the standard weight measurement before European regulation EC 1230/2012 introduced MiRO. The key difference is that MiRO includes a 90% fresh water tank fill (if factory-fitted) and follows a stricter measurement protocol. In practice, MRO and MiRO figures are similar but not identical. MiRO tends to be slightly higher. For motorhomes, MRO/MiRO includes a 75kg driver allowance.
Why this matters
If you are comparing weight specs between older and newer models, be aware that MRO and MiRO are measured differently. An older caravan quoted at 1,200kg MRO might actually weigh slightly more under the MiRO standard.
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Frequently Asked Questions
They measure similar things but use different standards. MiRO (introduced 2012) includes water and follows EU regulation EC 1230/2012. MRO is the older equivalent.