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Towing Trailers

All you need to know about your trailer, from the licence you need to the legal obligations you are tied to and the weight/size restrictions you must adhere to.


What the driver can legally tow?

When it comes to towing, there are strict rules on which licence you hold and the relative weights of vehicles and trailers.

If you passed your car driving test before 1st January 1997, you can drive vehicles up to 3.5 tonnes MAM towing large trailers (category B+E). You may also hold entitlement to drive categories C1 and C1+E, which allows you to drive vehicles between 3.5 and 7.5 tonnes MAM and tow a trailer, provided the combination does not exceed 8.25 tonnes. If you passed a standard test (category B vehicles) after 31st December 1996, the maximum combined weight you can tow is much lower. To find out what you are allowed to tow, you will have to make a calculation based on the weights of both the car and the trailer. Tthe key figures are:

• Category B vehicles can tow a trailer with a MAM up to 750kgs, provided the combined MAM does not exceed 4.25 tonnes.
• Category B vehicles can tow a trailer with a MAM over 750kgs, if the MAM does not exceed the kerb weight of the towing vehicle and the combined MAM does not exceed 3.5 tonnes.

For example:

Your car's kerb weight is 1.25 tonnes and it has a MAM of 2 tonnes. You can tow a trailer with a MAM of 1.25 tonnes because it is less than the kerb weight of your car and your combined MAM is under 3.5 tonnes. You can't tow a trailer with a MAM of 1.5 tonnes because it is more than the kerb weight of your car, even though the combined MAM would be under 3.5 tonnes. In this case, you would need to take a licence that covers B+E vehicle categories. You can take an extra test to qualify you for category B+E vehicles.

Renewal of licenses at 70

When the ordinary licence expires at the age of 70, you will retain your B+E category but your entitlements to drive vehicles with a MAM of more than 3.5 tonnes will become optional. You will have the choice of renewing these entitlements provided you can meet the higher medical standards.

What your vehicle can tow?

You must consult your vehicle's handbook, an authorised dealer or the manufacturer's website for the maximum specified trailer noseweight for the vehicle. Some will have different weights depending on the type of hitch being used.

Construction and use regulations

All vehicles and trailers have their maximum authorized mass (MAM) defined on a plate. Vehicles either show the maximum weight that can be towed or the gross combination weight of car and trailer, which allows you to work out the maximum towing weight. If you exceed the towing capacity or the payload of your vehicle it may be considered an offence under the Construction and Use Regulations. It may also invalidate the vehicle insurance and any warranty on the vehicle, as well as increasing the likelihood of a mechanical fault.


Trailers and caravans towed by vehicles with a MAM of 3.5 tonnes or less are limited to a maximum body length of 7m (excluding drawbar) and a maximum width of 2.3m. The maximum overall length of the combination is 18m.


It is a legal requirement that you fit additional towing mirrors when you are towing your caravan or any other trailer that is wider than the narrowest part of the rear of your vehicle. If you are towing blind, without towing mirrors, or using illegal towing mirrors (not E-marked), you can be prosecuted.

Towing speed limits

Towing units are limited to 50 mph on rural single carriageway roads and 60 mph on dual carriageways and motorways, provided there aren't any local or temporary lower limits in force.

Motorway lane restrictions

You can't tow trailers and caravans in the outside lane of any 3 or 4-lane motorway, unless of course you are told to or the nearside lanes are closed.

Parking restrictions

You can't use two on-street parking spaces for a car and trailer or caravan. You also can't park a trailer without lights on a public road at night, whether or not it is attached to a vehicle.

Trailer Maintence

Where to store your trailer

Where possible, leave your trailer on a hard surface, rather than grass or soil which will corrode the tyres, wheels, brakes and chassis over time. You can leave the handbrake off if parked on a flat surface, to stop the trailer seizing up, but chocks under the wheels are a good precaution. The coupling is a vital part of your trailer, so grease it well and cover it up. Also, always fit a lock as there's a healthy black market in stolen trailers.

Checks to make before a journey

A sound floor and ramp are a must, particularly for livestock trailers. So ensure that you have been on board and given your trailer a thorough check before loading up Also check hinges and fastenings to make sure they can't come open once you are moving. You can take extra precautions by double securing them with small karabiners or R-clips.
Tyres can fail sue to under-inflation, degradation or just age, and this is even more of a dander if your trailer has been standing dormant for some months. Keep them pumped up to their maximum pressure for the trailer's load capacity, even when parked up. On the road, under-inflated tyres flex too much, building up excess heat which causes blow-outs. Tyres that have degraded in the sun develop small cracks in the sidewall near the rim which cause them to fall apart. Whatever they look like when you set off, tyres can deteriorate quickly after being unused for a long time, so have a look at them every time you stop. Change the tyres every five years, and only use a reputable dealer. Never use a standard vehicle tyre - very few fit trailers. You should always have a properly inflated spare, a suitable wheel-brace and a jack.

Additional safety checks

Keeping the ball, ring and pin or hook coupling greased or lubricated will protect from rust. Always check to make sure the back-up connection mechanism works. For caravans with internal stabilisers, such as Alko or Winterhoff, make sure you clean all grease or oil from the tow-ball before coupling up or they will fail. You must use a breakaway cable or chain secured to the brake assembly, which will pull the brakes on if the trailer becomes detached. If you have a braked trailer, check the over-run brake regularly and adjust it if need be, its also useful to look at the wheel-bearings whilst doing this.

Loading your trailer

Always put out rear prop stands or supports before you load up if you have them- especially for vehicle trailers. If you don't, you'll strain the rear axle and chassis members. The front of the trailer may also lift and wrench the coupling off the hitch or even pick up the rear of the towing vehicle. The heavier the vehicle and the longer the trailer the more likely this is.

It's worth taking the time to understand the on-road stability of trailers, particularly platform trailers carrying heavy or tall loads. The centre of gravity should be just in front of the axle and at a height of no more than 95% of the track width of the trailer or no more than 40% of the distance from the trailer axle to the towing hitch, whichever is least. In general, platform trailers are less suitable than goods trailers for tall loads such as vehicles, but better for mass loads and access from the sides.

Coupling heights of close-coupled trailers

Unlike single-axle trailers which can adapt to different coupling heights, heavy duty close-coupled trailers need to remain level. If the coupling is too high, the trailer will run on the rear axle, straining suspension, running gear, tyres and chassis. In addition, the coupling could break away from the A-frame drawbar, putting too much weight on the towing bracket.

More common than a high coupling is a low coupling, which causes the trailer to run on its front axle and may cause the coupling to lift-off the ball completely. This is exceptionally dangerous when travelling at speed. In any event, both cases seriously affect braking. If you are unsure, a height adjustable towing bracket will helpto ensure you have the right coupling height. These require certain types of mounting with the top bolted to a rigid chassis cross member.

Towing Trailers

Glossary of Terms

Here's an explanation of some essential terminology and procedures surrounding trailers:

Breakaway cables, chains and loops:

Braked trailers must be fitted with a cable that links the trailer brake mechanism to the towing bracket, which will pull the trailer brakes on and then break in the event of the trailer becoming detached from the tow-car. Unbraked trailers must have a strong loop or chain to hook over the towing bracket to stop the trailer separating from the tow-car if it becomes detached. The loop should be short enough to prevent the trailer coupling hitting the road.

Close-coupled trailer: A trailer with two or three non-steering axles, with two wheels per axle. It is not permissible to travel with less than the designed number of wheels in operation.

Kerb weight: Sometimes called the unladen weight, this is the weight of the empty vehicle. This will be quoted in your owner's manual. There are different versions, try to avoid "EC Kerb weight" because it includes a notional weight for the driver.

Maximum Authorised Mass (MAM): This is your vehicle's maximum permissible weight, also known as the gross vehicle weight. This will be quoted in your owner's manual.

Maximum Combination Weight: The total permissible weight of the fully laden tow-car and trailer combined. This affects drivers with the minimum category B licence who passed their test after 31/12/1996 in patricular.

Noseweight: This is the weight pushing down on the towbar of your towing vehicle and there will be a maximum permissible noseweight which will be quoted in your owner's manual (there may be different weights quoted depending on the type of hitch being used).

Payload: This is the weight your vehicle can carry. This may be quoted in your owner's manual but it can also be calculated by taking the difference between MAM and the Kerb weight.

Towing on long journeys

Towing needs much greater concentration than just driving and takes its toll on you. It's sensible to plan for a much slower journey with stops for a break every 2 hours at the minimum. Check on traffic, roadworks and weather before you leave and keep an eye on the signs and an ear on the radio traffic reports on the way, this should help you avoid unexpected delays. When you do stop, it's sensible to do a walk-round and run through a series of checks. Feel the tyres for heat - if they're abnormally hot they're probably under-inflated; check the coupling, make sure the lights all still work and that catches are secure. Stand back and check the overall stance; if it's leaning to one side you may have a broken spring or suspension. Before you set off again, make sure you have plenty of fuel for the next stint - your range will be much shorter with that heavy weight on the back. As you continue your journey, keep an eye through the mirrors on the trailer. If something seems unusual, stop at the earliest possible opportunity to check it out.

Safety precautions
On a long tow, you're more likely to make unscheduled roadside stops, to check or secure something for instance, or just for a rest, so carry reflective jackets or waistcoats - particually if you are abroad. If you are in a breakdown or incident on an all-purpose road, it's likely you'll block part of the road, so highlight the scene as well as you can with hazard lights, cones or warning triangles, then call your recovery provider. You should NEVER work on a vehicle whilst still in the carriageway.

Motorway Driving
If you tow on motorways you really should have comprehensive breakdown cover as recovery of a trailer or caravan is considerably more time consuming and expensive. Recovery may be limited to certain times, a lane may need to be closed and you could need two recovery vehicles - that's double the cost! When the unforeseen happens, your priority should be the safety of your passengers and any other people involved. Get the outfit onto the hard shoulder if possible and use hazard warning lights and side lights to make your position clear - don't put out a triangle or cones. Get out of the vehicle on the side away from traffic lanes and stay away from the carriageway, and away from the hard shoulder too if it is safe. Never attempt repairs or a wheel change on the hard shoulder. The best way to call for help on the motorway is to use the nearest Emergency Roadside Telephone - follow the arrows on the roadside reflector posts. The operator will call your breakdown service and inform Traffic Officers of your location and circumstance.

Towing abroad

Some European countries have extra regulations for vehicles with trailers, so it is always a good idea to check before travelling. Scandinavia, for example, demands lower speed limits for trailers as does France but only where the maximum weight of car and trailer exceeds 3.5 tonnes and the total length exceeds 7 metres. You cannot drive in the outside lane of 3-lane motorways and you have to drive at 10 kph less than the speed limit on single and dual carriageways. You also have to leave a 50 metre distance from the vehicle ahead. This tells you how complicated it can be so put in some research on your route as well as knowing your dimensions and weight (Kerb weight / MAM).

Extra items Required
In most European countries you have to carry a warning triangle, spare bulbs, first aid kit, spare glasses and your vehicle registration documents. Austria, Belgium, Croatia, France, Italy, Slovakia, Spain and Portugal require high-visibility waistcoats or jackets to be carried in the passenger area and used by every adult in case of breakdown.

Length and weight restrictions
Some alpine countries, particularly Switzerland, limit the size of caravans and trailers unless they are towed by a 4x4 vehicle. Weight limits, particularly on bridges, relate to the Maximum Authorised Mass of the whole outfit.

Road priorities
Vehicles climbing hills generally have priority, except in some alpine countries where service buses have right of way. You are obliged to make it easy for faster vehicles to overtake safely even though they're supposed to give way to towing vehicles going up hills.

Hiring or buying a trailer abroad
In Europe all trailers over 500kg MAM are registered as separate vehicles with their own registration number. If you buy a trailer abroad you'll need to change the plate or cover it with a British one matching your vehicle. Lending a British caravan or trailer over 500kg MAM to someone abroad to tow with a foreign vehicle is very difficult as it needs to be imported and given foreign registration and documentation.

Goods, Boats and Motorbike Trailers

What can I tow?
Typically with maximum authorised mass (gross weight) of 300kg to 750kg, these types of trailers must be towed by a vehicle whose kerb-weight is at least double that weight. That means trailers plated between 500kg and 750kg need tow-cars of 1 tonne to 1.5 tonnes kerb weight - probably a large estate or medium 4x4 for the larger ones.

Baggage trailers are usually around half the width of most cars and only a metre or so long, so they are invisible in the rear-view mirror. Their narrow track means they hit road hazards like pot holes or speed humps that the tow-car straddles.

Lights and reflectors
All trailers must have side, brake, indicator and number-plate lights, while trailers over 1300mm wide also need rear fog lights. They must also have rear red triangular reflectors plus a pair of white front reflectors. A removable lighting board of suitable width is great if the trailer lives outdoors - just take the light board off and store it inside. For low motorcycle trailers, add some reflectors along the sides, as drivers and pedestrians often don't see them when they are unloaded.

Loading and unloading
Many boat, motorbike and quadbike trailers are un-braked and so need to be hitched up for loading and unloading. Boats are usually loaded away from the road, but for motorbikes and quads you may be on the road, so make sure you can be easily seen by other road users. You may also need room for a good run-up to get the bike up the ramp, or to stop it as it comes off.

Maker's plate and number plate
The trailer must be fitted with a maker's plate showing its serial number, gross weight, axle weights and noseweight. It must also have a number plate that matches the tow-car.

Wheels and tyres
Many small trailers have wheels with rims of less than 10" diameter, which means they turn up to 50% faster than the wheels on the tow-car. With a very basic tread, they're not designed to go over 60mph. Different manufacturers use different fixings so wheels are not easily interchangeable - carry a suitable spare wheel at all times.


There are a wide range of freefixing boat supports and rollers available to support the hull during transit and help with loading and unloading. They clamp onto the chassis members so they can be placed in the best positions.

Hot hubs and cold water: Always keep the wheel-hubs on a road-going trailer out of water, especially if they are hot after towing or standing in the sun. Water will be drawn in and emulsify the grease, making it useless. This will cause the bearings will fail, leaving the trailer stuck wherever it happens to be.

Straps, winches, cables, tie-downs and hooks: Boats sat on rollers can move or fall off, so use good quality lashing straps. For anything larger than a dinghy you'll need a trailer with a hand-winch for loading and this usually stays connected for extra security. Keep an eye out for damage to the winch wire which would weaken it and always handle the wire-ropes with good gloves as they can damage your hands. The cables or straps can snap under tension, so don't stand too close as they can cause injury. Lay a mat or blanket over a long winch cable so it's easy to spot and to reduce whiplash if it fails.


Motorbike wheels must be in fixed runways with 4 straps to tie it down; two at each end. The bike's suspension must also be compressed or the straps will come undone with obvious consequences! Motorbike trailers should have substantial runways with sides to guide the bike wheels up and stop them slipping about during the journey. The best ones have a cut-out for the front wheel. Depending on the size and weight of the bike, the loading ramp could be as long as the runway on the trailer, so give yourself plenty of room. Remember it's much easier to secure the bike standing on decking alongside the trailer runways than from the ground.


What can I tow?
There are a huge variety of different caravans, some almost double the size of others but it's the weight that determines if you can tow it. To tow a 2-axle caravan with a Maximum Authorised Mass (gross weight) over 1.5 tonnes, you need to have a "B+E" or equivalent driving licence. In terms of the tow car, there is a well-founded recommendation that the gross weight of the caravan should not exceed 85% of the kerb-weight of the tow-car. There are some 4x4s that can tow a heavier load but always follow the manufacturers' specifications. Don't forget, crosswinds can effect a caravan or the towing vehicle of any size.

Maximum size
The maximum length of the caravan body, excluding the drawbar and coupling, is 7 metres. The maximum width is 2.3 metres, when towed by a vehicle of 3.5 tonnes or less. The maximum length of the caravan and tow-car combined is 18 metres.

Weight distribution and noseweight
Correct weight distribution, position and nose-weight are vital for towing stability. Heavy items should be carried close to the axle, preferably slightly ahead, on the floor. Roof lockers should be empty, or virtually so, with the overall intention to lower the centre of gravity. Nose-weight on the tow-ball should be around 5-7% of the caravan's actual laden weight (typically 50-100kg) but you should never exceed specific limits for the car, caravan and towbar. Nose weight is closely linked to the payload of the tow-car and should be calculated as part of it. Best practice is to double the nose-weight for the calculation, in order to compensate for the leverage exerted behind the rear axle of the tow-car. Therefore, 75 kg actual nose-weight would be treated as 150 kg for the calculation, and leave only 250 kg remaining payload on the average car. Where bike racks are fitted to the rear of the tow-car, their loaded weight must be considered as a supplement to the nose-weight. Roof-boxes are also part of the payload, along with passengers and luggage.

Internal friction stabilisers and greased tow-balls
Several makes of internal friction stabilizers have appeared over the last decade and are now almost universal on new caravans. They use tensioned friction pads to grip the tow-ball on hitching, with the tension released to unhitch. Never oil or grease the tow-ball, as was previous good practice with other couplings - any lubricant rapidly destroys the friction pads. The tow-ball must also be hardened steel to generate the right grip. These can be noisy when towing on undulating roads.

Safety checks
Before you set off, there are some essential checks to go through. Close gas taps and lift connectors off the gas bottle(s), switch off all interior lights and other electrical equipment, disconnect the mains supply and carefully stow the cable. Empty the fresh and waste water tank. Place all loose equipment and heavy items as low as possible. Make sure windows and roof lights, doors, hatches and aerials are secured. Lift all the prop-stands and make a final check of nose-weight.

Towing mirrors
Only large cars, minibuses or 4x4s towing small caravans can get away with standard mirrors. For the majority of combinations, you must fit extension mirrors that let you see both along the side of the caravan and the road behind. Some taller tow-cars, such as large 4x4s, allow a view through the caravan where there are suitable windows at both ends.

Towing dollies
You often see motor-homes pulling cars behind them on towing dollies and there are strict rules on the weight of the car. If the dolly is un-braked and the rear brakes of the car can't be linked up, the car is considered an un-braked trailer which has a weight limit of 750kg for the car and dolly.


Horse, Stock and Van Trailers

Extra regulations Firstly, there are extra regulations that apply to anyone loading and transporting animals, and anyone who assists in cases of emergency. For reference, the legislation is The Welfare of Animals (Transport) (England) Order 2006 in conjunction with EC Regulation No. 1/2005. You can also consult a DEFRA leaflet ref: PB 12460 called Animal Welfare Laws - Now it's your duty to care.

Insurance and breakdown cover
Your insurance policy needs to cover you not only for the recovery of the vehicle and trailer/horsebox, but also for the removal of any animals in transit. The same goes for your breakdown assistance , you will need to have extra cover for animal rescue and veterinary help. Always keep details of rescue organisations and veterinary contacts with you when travelling.

Dealing with a breakdown
A breakdown with a load of animals can be incredible dangerous, especially in hot weather and on busy roads. Get as close to the edge of the road as possible, switch on hazard lights and put on a high-vis jacket if you have one. On side roads, phone your breakdown company. If you don't have it or the situation looks likely to worsen, call 999. On the motorway, you can use an Emergency Roadside Telephone to get assistance. If you don't have cover tell the operator exactly what you are carrying and any other information that will help them provide the best response quickly. They will have details of local specialists in horsebox or animal removal as well as a local vet if you need one. Remember there will be a cost for any service which is called out to assist you. It's tempting to stay with animals, especially if they are distressed, but it is better not to - it could put you at extra risk and couls possibly make the situation worse. Finally, don't change wheels on the road. You will almost certainly need a special jack and you will end up lying in the path of the traffic.

What can I tow?
Horseboxes and Stock trailers with 2 or 3 close coupled axles can have a Maximum Authorised Mass (gross weight) of up to 3.5 tonnes. At that weight, only the largest 4x4s can handle them - even pick-ups will struggle. The over-run braking systems common to these trailers put extra braking forces on the towing vehicle when decelerating or on hill starts. This is a problem for front-wheel drives, particularly in slippery conditions, using a 4-wheel drive will be a distinct advantage.

Livestock Trailers

Towing livestock trailers

Coupling height for level trailer
Animals will struggle to stand on a sloping trailer so keep it level. Most vehicles that can tow these trailers tend to have a similar coupling height but some will have adjustable height towing brackets. These allow the coupling height to be adjusted for loading but they do make it easier to drive off with the incorrect height. Vans with rear steps may not be suitable as they tend to have very low towing brackets, and you should not try to raise the height of the towing ball.

Floor, panels and fittings
It is essential that the floor, ramp, hinges, fastenings, restraint bars and tie-rings are completely sound. Over time, wooden floors, ramps and panels rot and crack, metal fixings and panels corrode, especially if they get covered in fertiliser or manure. Get on board and test every surface thoroughly and aggressively. If anything is a bit wobbly or unsound, especially the floor, replace it as it could result in an animal breaking through or falling out.

Loading van trailers
Offering as much space as a conventional van, these are often fitted with specialist equipment or refrigerated units. But they don't have a side door, so you need to think about how you load them . Remember a part-load at the back can seriously affect stability.

Rear visibility, mirrors
Always use good towing mirrors, even if the trailer is narrower than the towing vehicle. The views down the sides may look fine but it's easy to forget how big the trailer is. You can also place some high-visibility patches on the rear corners to emphasise them in your mirror.

Tyres, spare wheel and running gear
Keep tyres at their max specified pressure at all times to help stability and makes them last longer. Always remember a spare. Tyres can get covered in wet and covered in mud, as can the wheels and chassis, so they'll need regular professional maintenance.

Heavy goods, Plant and Low-Loader Trailers
The heavy trailers category includes platform, goods, plant (excavators, etc.), car-transporter and low-loader types. They are perhaps the least versatile because you have to carefully consider what you are loading before buying one - even a multi-purpose one. For example, a digger can easily weigh 2.5 tonnes and has a very high centre of gravity, so you need a low loader with a low centre of gravity rather than a seemingly versatile platform trailer which puts all the weight above the wheels.

A simple way to calculate where a loaded trailer's centre of gravity lies is to measure 95% of the track (wheel width) of the trailer or 40% of the distance from the tow-ball to the centre line of the axle(s).

Keep it level
These are all close-coupled 2 or 3-axle trailers and so must ride level on the coupling to share loading and braking weights evenly between the axles. You should take care not to park or ride over kerbs or steep ramps when loaded, as this will but unwanted extra weight on a single axle.

Rear prop stands required
For similar reasons, it's essential to use rear prop stands or in-built supports when loading and rolling or sliding machinery along the trailer. Not doing this could result in damage to the rear axle, bending of the chassis, lift the coupling off the tow-ball or lift the towing vehicle.

Weight distribution
Place the load over the axles or equally front to rear, with a little extra weight on the nose - no more than 100kg though or you may overload the coupling, Which would result in instability while towing. Zero or minus noseweight would lift the back end of the towing vehicle.

Maximum size and weights
A trailer with a MAM of up to 3.5 tonnes can be up to 7m long (excluding drawbar) and 2.3m wide, while the maximum overall length of the towing vehicle and trailer is 18m. At this size, the trailer needs to have front and side marker lights and reflectors. The load itself can overhang the trailer by 305mm to the sides and 1.0m at the rear with the addition of markers and extra lights.

Weight and width restrictions
Where minor roads and bridges have weight or width restrictions, they are based on the MAM (gross weight) of the vehicle or combination, not the actual load on-board at the time, so a road with a 2 tonne prohibition couldn't be used by a vehicle with a gross weight of 2.5 tonnes, even if it's empty and under the weight restriction.

For more information about towing trailers/caravans click here

See our step-by-step guide to reversing a trailer/caravan.

Video help with connecting trailers/caravans