Can my car tow a catering trailer?

This is the mistake we see more than any other, and it is the worst one to make because it is not fixable afterwards. People commission a trailer, wait eight weeks, then discover the car on the drive cannot legally pull it.

Twenty minutes now saves that. There are only three numbers involved.

The three numbers

1. Your car's maximum towing mass

Every vehicle has a maximum braked towing mass set by the manufacturer. It is on the V5C registration document and usually on the VIN plate under the bonnet or in the door shut. This is a hard limit. It is not advisory and it is not negotiable.

A small hatchback might be 750kg to 1,000kg. A mid-size estate or crossover is often 1,400kg to 1,800kg. A proper pickup or large 4x4 is frequently 2,500kg to 3,500kg.

2. The trailer's gross weight

Not the empty weight. The gross weight, which is the trailer plus everything in it: appliances, gas bottles, water, stock and the generator. This is the number on the trailer's plate, and it is what counts legally.

A loaded catering trailer is heavier than people assume. Water alone is a kilo a litre, and a full 50 litre tank is 50kg before you have put a single burger in the fridge.

3. Your licence category

This depends on when you passed your driving test.

• Passed before 1 January 1997: you generally hold grandfather rights and can tow much heavier combinations. Check your licence for category BE and for C1E.
• Passed on or after 1 January 1997: the rules were relaxed in recent years and category B drivers in Great Britain can now tow heavier trailers than they once could. The vehicle and trailer weight limits still apply though, and the rules differ in Northern Ireland.

Licence entitlement rules have moved about in the last few years, so check your own record on the GOV.UK "view your driving licence" service rather than relying on what somebody told you at a show.

Worked example

Say you have a 3.5m twin axle trailer with a gross weight of 2,000kg, and a family estate rated to tow 1,600kg braked.

That combination is illegal, regardless of your licence. The car's limit is the car's limit. Your options are a lighter trailer, a heavier tow vehicle, or a fundamental rethink, and all three are far cheaper to discover now than in eight weeks' time.

The things people forget to weigh

• The generator. A 6kVA unit is commonly 80kg to 100kg.
• Gas bottles. A full 47kg propane bottle weighs about 80kg with the cylinder. Two of them is a passenger.
• Water. One kilo per litre, and it moves about while you drive.
• Stock. A full fridge and freezer is easily 100kg.
• Nose weight. A separate limit again, usually 50kg to 100kg, and exceeding it makes the car handle badly even when the total weight is fine.

What to do before you order anything

1. Find your V5C and note the maximum braked towing mass.
2. Check your licence entitlement on GOV.UK.
3. Tell your trailer builder both numbers before the drawing is finalised.

We ask for your tow vehicle on the quote form for exactly this reason. If the trailer you want will not work with the vehicle you have, we would far rather say so at the drawing stage. Nobody enjoys that conversation at handover.

Rules change, so confirm the current position on GOV.UK before you commit. Related reading: what a catering trailer costs and the certificates you need.