Police tell me that 15 out of the last 20 motorhomes they waved in failed to pass the test. All were overladen, in one form or another, leaving their owners driving illegal vehicles. And not one of them admitted they knew they were anywhere near the limit.
Let’s hold a snap test. That holiday gear you normally take – how much does it weigh to the nearest 10kg? How about all the muddle, which never leaves the ‘van but lies unused in toolboxes, cupboards, drawers? Okay, when did you last take your motorhome to a weighbridge before a holiday and pay the minor charge to make a proper check? Does that silence mean ‘never’?
Time we did some homework.
The basic definition
How do manufacturers arrive at the payload figure for your motorhome? Firstly, they calculate the Maximum Technical Permissible Laden Mass (MTPLM) of the vehicle.
For example, a Bessacarr E520 has a MTPLM of 3,500kg. Next, they calculate the Mass in Running Order (MRO), which is the unladen vehicle plus 75kg to cover the weight of the driver, plus 90 per cent full water and fuel tanks, and engine coolants (the percentage-full figure may vary between manufacturers). For our example, the MRO is 3,190kg. If you subtract the MRO from the MTPLM, what’s left is the payload available: for the E520, it’s 310kg.
Big deal! That’s 6.89 airline suitcases,so what’s the problem?
Okay, were you aware that the MRO figure stated is usually for a standard spec ‘van? The extras you gloated over when you bought it, are not included, which means that your awning and poles (35-45kg), the bike rack (60-70kg), your flat screen TV (7kg), solar panel (5kg) and microwave (15kg) have just taken 122-142kg out of your payload... before you put your first can of beer in the fridge. That’s three of your holiday suitcases gone already, leaving a revised payload of 168kg to 188kg.
This has to cover your passenger(s) and pet(s), your bedding, a full fridge, a second canister of gas, shoes/boots/wellies, your CDs, your towels and clothes, plates and cutlery and your bikes. Then your folding chairs, picnic table, barbeque, your toolkit, that half case of wine (in case you get snowed in), all your stock of food, toilet fluid and torches.
Rule of thumb allowances
One way of checking is to strip your ‘van to its standard state, carefully weigh all the gear that lives in it permanently, then weigh every item you take out for your next planned holiday. Next, factor in the weight of your passenger(s) and your pet(s). The final number could give you a shock and force you to unpack about a quarter of what you deemed essential.
A quicker way to check where you stand is to use rough rule-of-thumb estimate figures. The Caravan Club suggests a tentative estimate of 75kg per adult passenger (their clothed weight and personal effects) plus at least 100kg for additional clothing, bedding, food and kitchen equipment.
It suggests an arbitrary figure of 30kg per younger child and 50kg per older child, although this will depend on age and size, then probably another 25kg of general payload allowance for each child.
Front and rear axle weights
That’s only part of the problem. Even if you keep inside your MTPLM, there’s another complication: how well have you distributed your packing through the ‘van?
Each motorhome specifies the maximum weight which can be carried on both front and rear axles, set with the stability and handling of the vehicle in mind. You will find these weights on either the VIN plate or the owner’s manual for your ‘van. For example, in our Bessacarr E520, the maximum weight for the front axle is 1,850kg and for the rear axle 2,000kg.
It’s very easy to exceed your payload and leave your motorhome illegal and unsafe.
There is a very helpful calculator provided by replating experts, SVTech, on its website: www.svtech.co.uk/lda Just click on the motorhome icon and enter some details and it will accurately ascertain if you’re overloaded.
If the police check your vehicle, it’s at their discretion what action they will take. Normally, they’re pretty reasonable: but even if they don’t fine you, they won’t allow you to leave until you’ve unloaded enough to bring you within your MTPLM figure – or have redistributed your packing.
Weight distribution formulae
If you have an accurate figure for the weight you are adding to your rear panel, you can calculate its effect on both front and rear axle:
New front axle weight (Fn) = F - [L(O/W)]
Where F is the existing load on your front axle,
L is the extra load from the new accessory, O
is the rear overhang and W is the wheelbase
New rear axle weight (Rn) = R + L + (F - Fn)
Where R is the existing weight on the rear axle, L is the additional load from the new accessory, F is the existing weight on the front axle and Fn is the new front axle weight.
To illustrate, with a rear overhang of 1.60m:
Fn = 1646 - [150(1.60/4.04) making 1,587kg
and Rn = 1780 + 150 + (1646 - 1587) = 1,989kg
Alternatively, if the rear overhang was 2.00m then:
Fn = 1646 - [150(2.0/4.04)] = 1,572kg
and Rn = 1780 + 150 + (1646 - 1572) = 2,004kg
This is an edited excerpt taken from the August 2013 issue of MMM magazine. You can buy a colour copy of the article for £5.95 - please email Jane Cotton and ask for details of this service.
Our Best Subscription Deal – Subscribe today.
More useful Motorhome pages:
Motorhomes for Sale | Motorhome Reviews | Sell Your Motorhome | Motorhome Advice | Motorhome Buyers' Guide
Motorhome News | Motorhome Features | Motorhome Forums
MMM (Motorcaravan Motorhome Monthly) Magazine | Which Motorhome Magazine | Motorhome Shows