Every year, thousands of British drivers hitch a caravan or trailer to their car and set off with absolutely no idea whether they are legal. Not recklessly so, most of them. They have just encountered a subject that seems simple on the surface and turns out to have three or four ways to get it badly wrong simultaneously. I have spoken to people who have been towing for five years and still had the nose weight calculation completely back to front. So let us go through this properly, from the beginning.
What towing capacity actually means on your V5C
Your vehicle’s towing capacity is not one single number. It is at least three, and confusing them is where most problems start. The figure most people look up is the maximum towing weight, which is split into two categories on every modern car’s specification sheet: braked trailer weight and unbraked trailer weight.
An unbraked trailer is something like a small flatbed or a compact boat trailer with no independent braking system. The limit for these is generally 750 kg across most cars, regardless of how powerful the engine is, because the car’s brakes are doing all the stopping work for both vehicles. A braked trailer, meaning a caravan or any trailer large enough to have its own braking mechanism, can weigh considerably more, up to whatever figure the manufacturer has approved. That figure varies enormously. A small hatchback might be rated to 1,000 kg braked. A large SUV or estate car might manage 2,500 kg or more. The number is published in your owner’s manual and on the V5C logbook. If it is missing, check the manufacturer’s website or ring the dealer.
Gross train weight: the number most new towers ignore
Here is the one that catches people out most often. Gross train weight (GTW) is the combined maximum weight of your fully laden car plus your fully laden trailer. Every vehicle has a GTW limit as well as individual axle limits, and exceeding it is illegal regardless of whether you stay within the stated maximum towing weight.
Picture this: you have a car rated to tow 1,500 kg and your caravan weighs 1,450 kg fully loaded. You are within the towing limit. But if your car has a kerb weight of 1,700 kg and you have four adults, a boot full of camping gear and a roof box on it, you are easily pushing 2,200 kg for the car alone. Add the caravan and your GTW is 3,650 kg. If the car’s GTW limit is 3,500 kg, you are over it. Simple as that. This is not a theoretical concern; an overloaded outfit is harder to brake and far more prone to snaking on the motorway.
You can check UK weight regulations and type approval requirements through the GOV.UK vehicle approval section, which also clarifies what applies to privately imported vehicles and those with modified specifications.
The 85% rule: guidance, not law, but still worth understanding
The 85% rule is the one you will hear most often at caravan club meetings, and it generates the most arguments. To be clear: it is not law. It is a safety guideline issued by the Caravan and Motorhome Club and the National Caravan Council. The rule states that for safe handling, your caravan’s maximum technically permissible laden mass (MTPLM) should not exceed 85% of your car’s kerb weight.
So if your car has a kerb weight of 1,600 kg, 85% of that is 1,360 kg. If your caravan’s MTPLM is 1,450 kg, you are outside the guideline even if you are within the legal towing limit. Why does it matter if it is not law? Because outfits running above 100% of kerb weight, where the caravan is heavier than the car, are genuinely difficult to control if a snake starts. The car’s rear is being pushed around by the heavier trailer rather than the other way round. I would strongly recommend staying within the 85% figure, particularly if you are new to towing and unfamiliar with how an outfit behaves at motorway speeds.
Experienced, confident towers sometimes run up to 100% of kerb weight with a caravan that has a good nose weight and a modern electronic stability system on the car. Beyond 100% is not something I would advise regardless of experience.
Nose weight: the calculation most people do completely wrong
Nose weight is the downward force the caravan or trailer exerts on the tow ball. Getting this right is arguably more important than the towing weight itself for day-to-day handling. Too little nose weight and the trailer snakes; too much and the car’s rear suspension is overloaded, the front axle lifts slightly, and steering becomes light and vague.
Every car has a maximum permitted nose weight, usually between 50 kg and 100 kg, printed in the owner’s manual. Every caravan has a recommended nose weight range specified by the manufacturer. Both limits apply. You must stay within the lower of the two figures.
To measure nose weight accurately, use a dedicated nose weight gauge or a set of bathroom scales with a block of wood to replicate tow ball height. Load the caravan as you would for an actual trip, with all your gear on board, before you measure. People who load the van on site after hitching up are not measuring real nose weight; they are measuring an empty guess. Heavy items should be loaded as low as possible and as close to the axle as possible. Move gear towards the front of the van to increase nose weight, towards the rear to reduce it.
What your driving licence allows you to tow
Licensing is a separate layer of complexity on top of all the weight calculations. Anyone who passed their car test after 1 January 1997 holds a standard Category B licence, which permits towing a trailer up to 750 kg maximum authorised mass (MAM) without restriction. To tow heavier trailers, you either need the combined outfit to stay within 3,500 kg MAM, or you need to pass a dedicated B+E towing test.
There are nuances around when your car’s MAM plus trailer’s MAM versus actual laden weights apply, and the full breakdown of what each licence category permits is worth reading carefully. I covered the full picture in our article on UK driving licence categories and what you can legally drive in 2026, which goes through the B+E test requirements in plain English.
One thing worth adding: if your outfit is legal under your licence but your car is not type-approved for towing, you may also have insurance issues. Some performance cars, particularly low-slung sports cars, have a manufacturer towing capacity of zero. As I noted in our look at the real cost of running a performance car in the UK, ownership of something sporty often comes with limits people do not notice until they need to tow something.
Common mistakes to stop making right now
Checking only the towing limit and ignoring GTW is mistake one. Measuring nose weight with an empty caravan is mistake two. Assuming a high towing figure means the car handles a heavy caravan well is mistake three. Some cars with a 2,000 kg towing capacity have very soft rear suspensions or no trailer stability control, and they are considerably less pleasant to tow with than a car rated to 1,600 kg but with a stiffer setup and a responsive stability system.
Mistake four is perhaps the most common in the UK right now: buying a caravan or trailer and only then checking whether the car can legally and safely tow it. If you are in the market for a new car specifically for towing, read our guide on the best tow cars under £40,000 in 2026, ranked for exactly this kind of use, before you commit to anything.
Check the numbers before you hitch, not after. Nose weight, GTW, your licence category, and your insurance policy’s towing clause. Four checks, five minutes, and you are legal and significantly safer than most of the outfits you will see on the A303 in August.
Frequently Asked Questions
What is the 85% towing rule in the UK and is it a legal requirement?
The 85% rule is a safety guideline from the Caravan and Motorhome Club, not a legal requirement. It states that your caravan’s MTPLM should not exceed 85% of your car’s kerb weight for safe handling. You can legally tow up to your car’s rated limit, but staying within 85% significantly reduces the risk of snaking at speed.
How do I find my car's towing capacity in the UK?
Check your owner’s manual first, as it lists braked and unbraked towing limits along with nose weight and gross train weight figures. Your V5C logbook may also show it. If neither source has the figure, the manufacturer’s website or a main dealer can confirm it using your VIN.
What is nose weight and how do I measure it correctly?
Nose weight is the downward force your caravan or trailer places on the tow ball when hitched. Measure it with a purpose-built nose weight gauge or bathroom scales and a block of wood at tow ball height, with the caravan fully loaded as it would be for a trip. Your car’s limit is in the manual; stay within the lower of the car’s limit and the caravan manufacturer’s recommended range.
Do I need a special driving licence to tow a caravan in the UK?
If you passed your test after 1 January 1997, your Category B licence lets you tow trailers up to 750 kg MAM freely. For heavier outfits, the combined MAM of car and trailer must stay within 3,500 kg, or you need to pass a B+E towing test. Drivers who passed before 1997 generally have broader entitlement already recorded on their licence.
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