Up to speed

In the August issue (p184),

Clive Nicholls enquired about speed limits based on his vehicle’s ULW (unladen weight).

Clive might actually be OK to drive at normal speed limits because, as far as I have been able to establish, the ULW is the MIRO (mass in running order) minus the 75kg allowance for the driver and minus the weight of a tank of fuel filled to 90%.

I contacted the Department for Transport back in July 2018 on the same subject and was informed by email that its typical advice would be to ask the manufacturer for the ULW of the vehicle (the motorhome converter in our case), as it can often provide this.

The DfT’s email went on to say that, if the manufacturer was unable to provide this, it may help to know the differences in UK legislation between the kerbside weight (which is basically the same as the ‘mass in service’ weight minus the driver) and the unladen weight as defined in The Road Vehicles (Construction and Use) Regulations 1986 (helpfully, it also provided the relevant extracts of these regulations in the same email).

Mass in service is the same as MIRO and includes the weight of a 90% full tank of fuel plus a 75kg driver allowance.

To add to the number of weight references we should be aware of there is a kerbweight, which includes a full tank of fuel, but no driver and no load other than the loose tools and equipment with which the vehicle is normally equipped.

From this information the DfT summarised that, to obtain the ULW of our ’van from the mass in service weight (MIRO) we would need to exclude the weight of the driver as well as fuel, liquids and any loose tools or equipment.

My ’van is an Auto-Sleeper campervan, so I also spoke with the company’s homologation engineer to ask for the ULW of our vehicle.

He said the DfT’s definition of ULW is unclear for motorhome conversions, but in our case the MIRO is calculated from the standard model “leave the factory weight” (or dry weight) plus driver at 75kg and 90% fuel (65kg in our case).

Based on all of this, he advised that to calculate the ULW, we needed to take the MIRO and then subtract the weight of the driver, as well as subtract the weight of the fuel, BUT, then add on any other options packs, etc, that we have had fitted.

However, he was able to give me the weights of these plus anything else added, which can be considered as a fixed part of the vehicle (things like a towbar or awning for example).

Hopefully there will be a homologation engineer available at Bailey to help in a similar way and establish whether the ULW of Clive’s motorhome is within the 3,050kg threshold.

Allan Davies