The C1 licence: can you drive a motorhome over 3,500 kg?

The figure that matters for your licence is the van's maximum authorised mass (MAM): the most it is allowed to weigh fully loaded, as plated by the manufacturer. It is not what the van weighs on the day, and it is not the unladen weight that decides some speed limits. You will find it on the vehicle's plate, usually in the door frame or under the bonnet, and in the handbook.

A category B car licence lets you drive vehicles up to 3,500 kg MAM. That covers most campervans and many motorhomes. Above that, up to 7,500 kg, you need category C1, GOV.UK says, and C1 also lets you tow a trailer up to 750 kg.

If you are buying a used motorhome, ask for the plated MAM before you go to see it. It decides whether your licence covers the van, and it is much easier to walk away from a van you haven't driven yet.

Quite possibly, if you passed your car test before 1 January 1997. Driving licence categories changed several times, and older licences that were issued as group A are now shown as category C1 among others, with restriction codes, GOV.UK's guide to old and new categories explains. For the oldest licences the C1 that comes over can carry a restriction code beside it, such as 107 on C1E, which limits the trailer combination; the codes are listed on the back of the photocard and explained on GOV.UK. A pre-1997 car licence also usually lets you drive a vehicle and trailer combination up to 8,250 kg MAM.

The way to be sure is to look. The categories are printed on the back of your photocard licence, and you can view your entitlements online through GOV.UK's view your driving licence service. If C1 is there, you can drive a motorhome up to 7,500 kg today.

If you passed on or after 1 January 1997, your car licence stops at 3,500 kg and you would need to add C1.

This is the part that catches people out. At 70, a driving licence has to be renewed, and then every three years after that, GOV.UK says. The car entitlement can be renewed online for free. C1 cannot. You must renew C1 (medium-sized vehicles) and D1 (minibus) entitlements by post, using form D46P.

If you let C1 lapse, you keep your car licence, but a motorhome over 3,500 kg is no longer one you can drive. If you own a heavier van, plan around that birthday: either keep C1 going or move to a van plated at 3,500 kg. Check your van's MAM well before you turn 70, not after.

Adding C1 means a provisional licence, a medical and tests. GOV.UK's route is the same as for other larger vehicles: fill in a D2 application form and a D4 medical examination report. The D4 has to be completed by a doctor, either your GP (an optician may need to fill in the eyesight section) or a private firm that specialises in drivers' medicals, and they can charge for it. You can get both forms from a Post Office that offers DVLA services.

The Driver Certificate of Professional Competence (Driver CPC) is for people who drive a lorry, bus or coach as the main part of their job, GOV.UK says, so it does not apply to driving your own motorhome on holiday. You still need to pass the C1 driving tests, and a training school that teaches C1 can prepare you for them.

With a car licence taken on or after 1 January 1997, you can tow a trailer with a MAM up to 3,500 kg, GOV.UK says, within your car's own towing limit. Drivers with a pre-1997 licence can usually drive a car and trailer combination up to 8,250 kg MAM.

With C1, the trailer limit on the motorhome is 750 kg. To tow anything heavier behind a C1 motorhome, a small car on a trailer for example, you need C1E, which covers C1 vehicles with a trailer over 750 kg as long as the two together do not exceed 12,000 kg MAM.

The maximum authorised mass on the plate is a limit, not a description. Everything you put in the van counts against it: water in the tank, gas, fuel, food, bikes on the back, the dog, and you. The difference between what the van weighs ready to go and its MAM is your payload, and on a van plated at 3,500 kg it can be smaller than you expect once a full fresh water tank and a bike rack are on board.

The Highway Code asks for extra attention to the vehicle's condition when it is heavily loaded, and for luggage to be securely stowed. The only way to know your real weight is to drive onto a public weighbridge, fully loaded as you would tour, and compare the ticket with the plate. It is worth knowing before a long trip, not after.

Tyres must be inflated to the vehicle manufacturer's specification for the load being carried, the Highway Code says in its maintenance annex, so a fully loaded motorhome may need different pressures from an empty one: check the handbook. Check them before a journey, when the tyres are cold, because warm tyres give a misleading reading. Cars, light vans and light trailers must have at least 1.6 mm of tread across the central three-quarters of the tread and around the whole circumference.

Under-inflated or over-inflated tyres affect braking and steering, and uneven wear can point to a brake, suspension or alignment fault. On a heavy van that spends winter on the drive, a tyre check is the first job of every season.

Licence weight and speed limits use different measures. Your licence is about the maximum authorised mass. Speed limits for motorhomes split at 3.05 tonnes unladen weight. A van can need only a car licence and still have the lower motorhome speed limits, or the other way round. The full table is in motorhome and caravan speed limits.

Heavier vans also meet more weight limits on country lanes and in car parks. Each base in the Park Up & Walk guides has a driving page listing the height, width and weight limits mapped near the campsites, so you can see before you go whether a 3.9-tonne van will get to the car park at the start of the walk. In the Lake District, where the lanes are narrow and the car parks small, it is worth reading that page twice.