03/12/2018
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Motorhome weight and payload: A beginner's guide

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It’s easy to overload a motorhome and yet driving an overladen vehicle is dangerous and illegal. Peter Rosenthal advises on how to stay safe and within the law...

Driving licence categories and over 70s

What do all the motorhome weight numbers mean?

Why is it dangerous to overloaded a motorhome?

How to work out your motorhome's payload

What to do if your motorhome is overweight

How to replate a motorhome to a higher weight limit

Should I get a trailer for my motorhome?

Payload considerations when buying a new motorhome

Payloads have never been under more pressure in modern motorhomes and, in many ways, it’s our fault. We want air-con, satellite TVs, electric beds, larger fridge/freezers and awnings. But each of these come with a weight penalty.

While motorhome designers can build a heavier vehicle using an uprated chassis, the issue is that, to appeal to the maximum number of buyers, it ideally needs to weigh under 3,500kg. This can be quite a challenge, especially if a meaningful payload is to be achieved.

The end result is that it’s easy to overload a motorhome, which is not something you can overlook, either: legally it’s your responsibility to know the weight of your motorhome. Ignorance of the weight is not a legal defence. And you will need a legal defence if you’re heavily overloaded as you’ll get a court summons. So how do you avoid this?

Driving licence categories and over 70s

If you passed your driving test after 1 January 1997 and before 1 January, 2013, you will have category B and B1 on your driving licence. This limits you to driving motorhomes of up to 3,500kg and trailers of up to 750kg. To drive a motorhome of over 3,500kg, you will need to take an additional test to gain the C1 category.

If you passed your driving test before 1 January 1997, you should have C1 and C1 + E categories on your licence, which allow you to drive motorhomes up to 7,500kg and to drive a motorhome and trailer with a combined weight of under 12,000kg if you have also passed your full trailer test, otherwise the combined weight is capped at 8,250kg.

When you reach 70, you’ll need to renew your driving licence every three years. While you will automatically retain categories B and B1, you will need to submit a D4 and D2 medical form to retain C1, which your doctor will need to fill out every three years. Depending on your medical details, this isn’t set in stone – for some conditions you may need to renew more frequently.

B and B1 categories for motorhomes under 3,500kg can be renewed online, but licence category C1 renewals (for motorhomes up to 7,500kg) must be done by post using form D47PU. Always renew your licence well before it expires – especially during summer holidays when the DVLA is busiest. You should get renewal forms by post 56 days before your current licence expires.

What do all the motorhome weight numbers mean?

If you look in your vehicle handbook, brochure or on the chassis plate, you should find a list of weights. These can be displayed in various ways, but the key numbers to look for are: Axle 1, Axle 2 (sometimes referred to as maximum axle weight – MAW) and the total or maximum laden weight. This is often referred to as maximum authorised mass (MAM), gross weight, gross vehicle weight (GVW) or permissible maximum weight or even maximum technically permissible laden mass (MTPLM).

They all mean the same thing: the total weight of the vehicle when it is carrying its maximum payload. As well as not exceeding the MAM, you also need to make sure that the weight is evenly distributed and not exceeding any individual axle load.

Why is it dangerous to overloaded a motorhome?

An overloaded motorhome can put more strain on the tyres and, if the pressures are not set correctly, risk premature wear or failure. Click here to read our feature on tyre pressure monitoring systems in motorhomes. 

Equally, the suspension is only rated for a certain load and may sag sufficiently to cause it to ride low. If heavily overladen, the motorhome can even ride on the bump stops and have limited suspension travel and a very hard ride. Bump stops are hard blocks of rubber than are designed to protect metal components in the suspension hitting together when the springs and dampers are fully compressed. If a motorhome is running on its bumpstops, it will fail an MoT.

Many modern vans use spring assisters on the rear leaf springs. These look like the rubber bump stops but are actually a softer cone that is designed to run in contact with the leaf spring/axle and form an integral part of the suspension. A motorhome running on its spring assistors should not fail an MoT so make sure you ask the tester to check this.

As well as mechanical issues, an overloaded motorhome will take longer to decelerate under braking and will sway more when cornering or if you suddenly have to change lanes in an emergency. In short, it’s more dangerous to drive.

Additionally, an overloaded motorhome may be uninsured and, if you are over 3,500kg and your licence doesn’t allow for that, then you could face two offences – an overloading offence and a licence offence with fines of up to £1,000 for the licence transgression and six penalty points. Weight limits are monitored by the Driver and Vehicle Standards Agency (which took over from VOSA in 2014).

New technology means that your motorhome can be weighed while it’s in motion and many motorways have this technology built in. It’s linked to cameras that detect number plates and can automatically compare the vehicle’s actual weight with its registered weight. This weight-in-motion (WIM) system was primarily brought in to tackle overladen trucks, but works just as effectively on motorhomes. We know VOSA has targeted vehicles leaving or arriving at motorhome shows in the past. We understand there are at least 12 WIMs in the road network but some estimates now put this at nearer 50.

If you’re caught driving an overweight motorhome, you’ll either get an on-the-spot fine of up to £300 per offence, or be issued with a court summons. If the motorhome is deemed unsafe, you may be prevented from carrying on with your journey.

How to work out your motorhome's payload

Your payload is the difference between the maximum weight of your motorhome (MTPLM, MAM, etc) and what it actually weighs before you’ve added all your kit and accessories. Subtract the latter from the former and you have your payload. This is the maximum weight you can add to your motorhome. Don’t forget to allow for the weight of passengers, water (some manufacturers allow this in their calculations and some don’t), fuel, spare gas bottles, etc, which are all easy items to overlook.

Then you need to consider the weight of all the options you have added, such as an automatic gearbox, cycle rack, satellite TV system, air-con unit, etc, all of which will eat into your payload. Then add in the weight of all your touring items (clothes, food, chairs, bedding, levelling blocks, hook-up lead, etc).

While you can weigh each item, this still assumes that the original brochure weight is correct and this isn’t always the case. You can get a rough idea of your weight by using an online weighing calculator, such as the free one listed on SvTech’s website.

But the most accurate method is to get the motorhome weighed with all your touring kit on board. For this you’ll need to visit a local weighbridge, agricultural merchant or even a scrap metal yard. For a modest fee – usually under £10 – you can drive onto a lorry-sized weight pad and have your vehicle weighed. Drive on so that only the front wheels are on the pad first, as this will give you the front axle weight figure. Then drive all wheels on, which will give the total weight.

The total weight minus the front axle weight will give your the rear axle load (which will need to be divided by the number of axles on tag-axle motorhomes). When you have the front and rear axle weights, check you’re not overloaded and contact your tyre manufacturer and ask for its recommended pressures.

What to do if your motorhome is overweight

If your motorhome is only slightly overweight with all your touring kit on board then the first thing to do is to have a clear out. Do you really need to carry that inflatable boat with the hole in that you’ve not got around to fixing? Are 40 litres of bottled water essential? Be ruthless – any item that hasn’t been used in the last year, leave at home.

Don’t forget food: it’s easy to overlook that a tin of baked beans weighs around 0.45kg, a bottle of beer is 0.8kg and a 75cl wine bottle is typically 1.3kg. We were surprised to find that four pints of milk weighed 2.4kg! Even a cutlery drawer, probably contains about 2kg of silverware.

After a thorough declutter, weigh each item you’ve removed (a simple method is to simply hold an item and stand on your bathroom scales, then subtract your weight). If this gets you under the weight limit, great. If you’re nearly under the weight limit, then consider emptying your fresh water tank (always travel with an empty waste water tank) and refilling it on the campsite. One manufacturer already recommends not travelling with any water at all.

If, after clearing out all your touring kit, you still can’t get under the weight limit, you have three options:

  1. See if your existing motorhome can be replated to a higher weight limit 
  2. Trade it in for a motorhome with a higher payload 
  3. Get a trailer fitted and decant some of your equipment to it.

How to replate a motorhome to a higher weight limit

If you have C1 category on your licence you may be able to get your motorhome replated to a higher weight limit. SvTech is one of the leading firms in this field and can often be found at Warners shows. It’s based in Leyland, Lancashire.

Depending on the model, replating may be a simple paper exercise that results in SvTech issuing a new weight plate for a set fee. In some cases it may mean that mechanical modifications need to be made to the vehicle to safely increase the load it can take on each axle. This can involve beefing up the springs and dampers, fitting air-assisted suspension or even installing full air suspension to each corner of the vehicle.

Mechanical modifications all carry a cost (a basic rear air-assistance set-up will cost from around £500) and this needs to be factored in. Equally, if the motorhome is replated to a higher limit, it could impact on its resale. Air-assisted springs can be a great upgrade in general, though, as they can vastly improve the ride quality and handling of a motorhome.

Should I get a trailer for my motorhome?

The first point to make about trailers is to consider if your motorhome is suitable for a towbar. If it has a garage, or a long rear overhang, a substantial frame will need to be in place to allow a towbar to be fitted. The weight of this needs to be taken into account. You also need to know the maximum tow weight of your motorhome – check with the converter. It is typically from 1,500kg to 2,500kg.

If you have a motorhome first registered on or after 1 April 2012, the towbar must be EC type approved. Any good motorhome specialist towbar supplier will have a range of brands that will meet these approvals. For vehicles registered prior to 1 April 2012, you have a little more flexibility in towbar versions. With a towbar and suitable electrics fitted, you then have to consider the sort of trailer will be best.

Again you need to check your driving licence – the categories you have will depend on when your licence was issued, any medical conditions or what tests you’ve passed. Category B allows you to drive trailers of up to 750kg if the motorhome is no more than 3,500kg. Category C1E allows you to drive a motorhome of between 3,500kg and 7,500kg with a trailer of over 750kg. C1E is usually linked to a restriction code 107 (as printed on your driving licence), which limits the total weight of motorhome and trailer to 8,250kg. So, for a 3,500kg motorhome, you can tow up to the maximum towing limit with this code.

Any trailer (or car on an A-frame) that you tow that weighs over 750kg must have a separate braking system fitted to it. You will also need to allow for the noseweight of the trailer. This is the force that pushes vertically downwards onto the head of the towball.

Towbar makers will issue their towbar with a maximum noseweight. Typically it is between 75kg and 100kg. Whatever noseweight figure your trailer exerts on the towball must be accounted for with your payload. If it exceeds your payload or noseweight limit, you can adjust the loading of the trailer to reduce the noseweight.

With a box trailer you ideally want to place heavy items low down and centrally over the axle (or axles). Load them evenly and as level as possible. Secure or wedge items carefully so they can’t move in transit and alter the weight distribution. A towed trailer or car on an A-frame must have rear lights and display reflective triangles.

Before you invest in a trailer, consider how easy it is to move around – small, single-axle box trailers are easy to move around by hand, while larger twin-axle trailers require much more strength or two people to manhandle. You may even need to consider caravan motor movers on larger trailers.

Payload considerations when buying a new motorhome

Firstly check your licence code categories with care – especially if you’re aged over 70. If you are limited to a 3,500kg motorhome, then think carefully about the weight of each and every optional item you specify. You’ll need to tot these up as you go.

This is further complicated as manufacturers tend to quote the weight as the mass in running order (MIRO), which may exclude such items as gas bottles and leisure batteries. The MIRO is often listed with a 90% filled fuel tank, empty water tanks, 6kg to 15kg allowance for gas bottles and a driver weight of 75kg. But this varies between manufacturers, so read the brochure small print for any motorhome you’re thinking of buying.

Every addition – from decals to a towbar – has a weight that needs to be subtracted from the available payload. It’s not just the manufacturer options you need to consider, but also the dealer-fit items such as the awning, satellite TV dish and solar panels. Even the new crockery you buy from the dealer shop to match the new motorhome's upholstery needs to be taken into account.

For more practical and technical motorhome advice, click here.

MMM September 2018

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