Motorhome advice: speed limits, tyre pressures, dust covers and more
In each and every issue of MMM, the magazine's team of technical experts answer your queries about motorhomes and campervans.
Got a pesky problem that you need some assistance with? Our team can help. Between them, they're armed with some seriously impressive motorhome knowledge and an understanding of what makes them tick.
You can read the latest technical questions from MMM readers below, with answers from the team. If you have a technical question of your own, please get in touch – by emailing our experts at email@example.com. We'll take it from there.
You can buy digital issues of MMM magazine here
Meet the MMM Tech Help Team:
Nick Fisher – Tech Help Editor and Base vehicle expert
Peter Rosenthal – General advice
Clive Mott – Electrical expert
Mike Hill – Bodywork expert
Barry Norris – Technical & legal advice
Brian Kirby – All round expert
Andy Harris – TV & 12V expert
Q: What is the legal speed limit of my motorhome?
I have a 2013 Auto-Trail Tracker RS and have only just realised there are differing speed limits for motorhomes with unladen weight (aka mass in running order/MRO) over 3,050kg. I thought 3,500kg was the magic number.
The vehicle has – as per the log book – a mass in service of 3,050kg. I think this is the same as MRO. The manufacturer’s brochure on the vehicle says the unladen weight or MRO is 2,995kg, which includes a driver at 75kg, 90% fuel, 20 litres of water and a gas bottle that’s 90% full.
On this basis, it appears the vehicle is classed as at or under 3,050kg and, as such, one which can travel at up to 70mph on motorways and dual carriageways and 60mph on other roads (without a lower speed limit).
Is this correct?
It’s worth mentioning unladen weight is not the same as mass in running order (MRO) or mass in service. The definition given on the gov.uk website for the unladen weight of any vehicle is: the weight of the vehicle when it’s not carrying any passengers, goods or other items. It includes the body and all parts normally used with the vehicle or trailer. It doesn’t include the weight of fuel or batteries in an electric vehicle.
The MRO figure quoted by motorhome manufacturers will include 75kg for a driver, and allowances for 90% of fuel capacity, a set amount of gas and other items of essential equipment. Often the allowance for water is zero. Clearly unladen weight will be less than MRO.
A motorhome with an unladen weight not exceeding 3.05 tonnes is permitted to travel at up to 70mph on motorways and dual carriageways and 60mph on single carriageways unless signs indicate otherwise or you are towing. As this is a concession for motorhomes, do check your V5C to ensure the body type shows motor caravan. Without this on your V5C you can be booked for travelling over 50mph on a single carriageway and 60mph on a dual carriageway.
Details of speed limits can be found on the government website
Q Can I get dust covers for my campervan?
Do you know of anyone who makes dust covers for a campervan that is 6.36m long? I know there are plenty of heavy-duty covers out there (multi-layer, waterproof, snowproof, etc), but these weighty items are a nightmare to put on and take off.
I store the campervan in a barn and all I need is something lightweight and breathable to keep the dust and bird droppings off.
Having used all sorts of indoor covers over the years, the key thing here is that covers tend to fall into two types: outdoor ones that are designed to be highly weatherproof and indoor covers designed to be used in garages that are fully protected against weather elements. A barn is a different proposition as these tend to be much more exposed.
Indoor covers are less tight fitting than outdoor ones, as most garages are not subject to any wind so there’s little risk of them blowing off.
The majority just have an elasticated lip around the base to attach them.
Most barns I’ve seen, even those with doors, tend to allow the wind to blow through them. If birds can get in, the barn can’t be that windproof.
Equally, indoor covers are not waterproof, so any bird dirt will get through. So, there’s little point in using an indoor cover in a barn.
As you correctly point out, outdoor covers are designed to be weatherproof (though most decent-quality ones are also breathable) and tend to be much more hard-wearing and durable. The flipside to this is that they are often made of several different layers of durable material – often with a fleecy inner surface and weatherproof outer layers – and this makes them heavier and bulkier.
Fitting any kind of exterior cover can be a challenge and it’s a time-consuming job to do every time you have to remove it. Equally, you need somewhere to store the cover when it’s not in use (in the barn, possibly, as your campervan is unlikely to have a garage).
If you use your campervan regularly, this is a factor to think about – you might not want the faff of removing a cover and refitting it just for a weekend away and it might affect how you use the vehicle.
The other point to make is that cheap unlined outdoor covers can wear through the paintwork of the vehicle if they’re exposed to any wind as they tend to flap at the edges of the vehicle.
With all covers you need to be careful when you take them on and off that you don’t drag any dirt over the paintwork and corners of the vehicle. The cheap non-breathable covers can also trap layers of condensation between the cover and body, which can cause paintwork issues and can even cause blistering on gelcoat surfaces.
So, if you do choose to fit an outdoor cover, then I’d only suggest using a high-quality, breathable cover from somewhere like Pro-Tec or one from Specialised Covers. These will not be cheap – expect to pay upwards of £400.
The key benefit to high-quality outdoor versions is that they protect the vehicle from UV damage, bird dirt and things like tree sap, all of which harm paintwork. So I’d either use a high-quality outdoor cover, or nothing and resign yourself to having to rinse off bird dirt every couple of weeks.
Q What is the correct tyre pressure for my motorhome?
I am trying to establish the best tyre pressures for our 2006 Peugeot Boxer-based Autocruise Starburst motorhome and it’s proving to be rather confusing! The tyres that are fitted to the motorhome are Michelin Agilis Camping 215/70 R15 CP 109 rating.
I have checked the actual fully laden weight on a weighbridge (with two people, full tanks of fuel and fresh water, cycle on rack, clothes, food and drinks, and all accessories, etc.).
- Front axle: 1,655kg (maximum 1,750kg)
- Rear axle: 1,630kg (maximum 2,000kg)
- Total: 3,285kg (maximum 3,500kg)
The Autocruise Starburst manual states that the tyre pressures (as recommended by Michelin Tyres) are 55 psi for the front and 45 psi for the rear. However, the recommended tyre pressures on the label on the driver’s door pillar are 72.5 psi front and rear.
I have entered the tyre details and the above axle weights onto the tyre pressure calculator on the tyresafe.org website and it recommends the following pressures of 59 psi for the front and 80 psi for the rear.
Clearly, these recommended pressures vary considerably.
The pressures recommended in the Autocruise Starburst manual seem very low, particularly as I understood that motorhome recommended tyre pressures are generally supposed to be higher than the base vehicle (Boxer) pressures due to motorhomes being constantly fully loaded.
A: Yes, it does look confusing, doesn’t it. I’ll try my best to explain how I see things based on years of dealing with such queries and many discussions with tyre experts.
Three things to consider:
- permissible axle load and gross vehicle load
- actual loadings
- =ype of tyres as fitted (C or CP) and consideration of the load index rating
Hopefully, you will have downloaded Tyresafe’s motorhome safety leaflet, which shows that a tyre with a load index of 109 has a maximum load bearing capacity of 1,030kg, giving a maximum axle loading of 2,060kg.
Your tyres are therefore capable of meeting the requirement of carrying your maximum permitted axle loads, given a suitable inflation pressure.
Also in the leaflet is the recommendation to have a margin of safety when selecting tyres so your maximum axle load does not exceed 90% of the maximum load capability of the tyres. This will also partly compensate for unequal load distribution.
When you go to a weighbridge to measure your axle loads, you assume the load is equally distributed across the axle. There is always the possibility loading is not equally distributed, especially if, like some travel writers, a driver throws in a couple of crates of wine into one corner of the rear garage on their way back from France.
Within the tyre industry and safety organisations the main discussion point with regard to motorhome tyres is failure from overloading.
In particular, overloading of the rear axle is common with bike racks and rear garages where the full weight of loading goes onto the rear axle; plus, with a rear overhang, you get transfer of loading from the front axle.
It is from that point of view I believe the Tyresafe tyre pressure calculator advice is for a blanket inflation pressure of 80 psi at the rear.
However, a tyre industry expert I have discussed this with is firmly of the belief that tyres should be inflated to the pressure that is appropriate for the load being carried rather than a blanket rear maximum tyre pressure as given by Tyresafe’s pressure calculator.
Obviously, setting tyre pressures to the maximum pressure on the rear axle and a pressure on the front axle to support the maximum permitted axle limit provides a safety factor against overload of the tyres, albeit possibly giving a much harsher ride.
I keep my tyre pressures down from the maximum as my fully loaded weighbridge weights are so much lower than the vehicle maximum axle weights. I work on the basis of adding at least 10% to the weighbridge fully laden figures.
On this basis, adding 10% to your figures, your front axle loading (1,655kg) becomes 1,820kg and rear axle (1,630kg) becomes 1,793kg. Tables from Continental’ s technical data book, using your tyre specification, show a tyre pressure of about 4.1 bar (60 psi) for your front axle load and about 4.75 bar (69 psi) for your rear loading.
This ties in with figures in the table provided by Tyresafe (although using Tyresafe’s table pressures for a rear-driven wheel, while Continental simply states lower loading figures for a rear single axle).
I assume your tyres are not the original fitment so the Autocruise recommendations may well be quoted for a different tyre (probably not a CP tyre), although I cannot understand why the rear axle figure is so much lower than the front axle. Similarly, the label on the door pillar may well relate to the original commercial vehicle specification rather than the conversion, where tyres for a commercial van would not have been a CP fitting.
If using tyre pressures related to your actual fully loaded conditions, do be sure your loading at the weighbridge does truly represent fully loaded and always make a 10% allowance to provide for any uneven distribution of loading.
Q Where can I find the right handbrake cable?
I have a 2004 Bessacarr E725, on a 2.8-litre Fiat, which has a sticking handbrake. The rear brakes are discs with a drum and brake shoes for the handbrake.
I tried to remove the disc/drum to see if I could find the problem, but was unable to remove the caliper carrier. I decided to take the motorhome to a local garage, which found the handbrake cable was at fault, so ordered one from a motor factor.
When the handbrake cable arrived, it was the wrong length, but had the correct fittings. The garage is now not sure of the exact cable needed for the Bessacarr and is wondering if it was fitted with a bespoke handbrake cable. If so, where would we obtain one from?
A: Your Bessacarr is built on a Fiat cab but with an Al-Ko chassis attached, so the original Fiat bits end with the first piece of handbrake cable attached to the handbrake lever in the cab. From there backwards it is a mixture of Fiat parts and bespoke parts.
Al-Ko tended to use standard wheel hubs and brake components (which is why the pads, shoes and cable fixings are the same), but the distance that these are from the pick-up points on the chassis are quite different, not least because of the wider track that the chassis has over a standard Fiat chassis.
I remember that the cables needed to be sourced from an Al-Ko dealer and your local motorhome specialist should be able to pinpoint the correct cables for you. Motor factors are highly unlikely to be able to identify the correct items.
Don later added: Thank you. I passed on your comments about the Al-Ko chassis to the garage and it found a part number on the cable and contacted a local Al-Ko dealer, which was able to supply the correct part. Our Bessacarr is now up and running.