Payload is a general term to indicate the weight that may be carried in a motorhome or a component part fitted to it before it reaches its maximum permitted weight on the road.
National Caravan Council (NCC) approved motorhomes generally indicate a Mass in Running Order (MiRO) and a Maximum Technically Permissible Laden Mass (MTPLM) – also known as the Maximum Authorised Mass (MAM). Payload is considered to be the difference between the two figures and the allowable weight you can put on board.
Unfortunately, while the MTPLM is a fixed figure and equivalent to the MAM indicated on the vehicle weight plate, MiRO now varies depending on the manufacturer. It normally includes the motorhome in a condition ready to travel, with 75kg allowed for the driver, 90 per cent full fuel tank and gas tank loaded to 90 per cent of normal capacity. It may also include an allowance for freshwater, with older UK motorhomes often allowing for a 90 per cent full tank. However, now UK and Continental manufacturers usually allow for either an empty tank or one filled to 20 per cent capacity. The amount of gas allowed for in the MiRO can be limited to just one lightweight cylinder even though the gas locker has room for two cylinders – and standard heavy ones at that.
Many smaller motorhome converters are not part of the National Caravan Council (NCC) Product Approval Scheme and may simply class payload as the difference between the MAM and the unladen vehicle weight.
However the payload is calculated or described, the crux of the matter is every motorhome has a weight plate showing its MAM and weight limits for the axles and these limits must not be exceeded and should not been seen as a target weight to aim for.
Police roadside weight checks reveal many motorhomes on the road are overloaded. Apart from the risk of being taken to court and fined, overloading has the potential to cause failure of tyres and suspension systems and affect braking and handling performance.
Public weighbridge and plated weights
At the earliest opportunity, take your motorhome to a public weighbridge, filled as you would expect for a major trip and take along the normal load of passengers.
Have the motorhome weighed twice on the weighbridge, one with both axles on the weighing platform and another with one axle just off the platform. From these readings you can check your vehicle is within the permitted MAM and the front and rear axle loadings, as shown on the vehicle plate usually found under the bonnet.
If any weight exceeds the plated limit you will need to reduce your payload or consider the possibility of replating the vehicle for a higher weight limit – assuming your driving licence will permit you to drive a larger vehicle. You are advised to consult a specialist company like SV Tech which will be able to advise if such an action is possible. Going above 3,500kg you will no longer be able to drive the vehicle on a B-class licence – the standard car licence obtained after 1 January 1997.
Adding bike racks and back boxes
Bike racks, boxes and loading of rear garages are particular critical loading situations. Ensure the motorhome is designed to take the load you are intending and any bike rack is also rated for the bikes you want to carry. Electric bikes are generally considerably heavier than standard cycles and motor scooters and motor bikes are even heavier.
Dangers of rear loading
Heavy loading at the extreme rear provides the real possibility of overloading of the rear axle. Not only is this unlawful, the effect of reducing the front axle load due to a tipping rearwards means general handling and in particular steering and traction may be severely affected.
Suspension aids and modifications are available but these are generally aimed at improving the quality of ride. They will not enable you to exceed the plated weights of your vehicle.
Secure all loads
Always check external and internal loads are secured in place. Remember you – the driver – are responsible at all times in law to ensure you do not overload your vehicle or allow it on the road in an unsafe condition