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Towing weights & the law

Before towing, it is essential that you check your towing vehicle is capable of legally towing your fully laden horse trailer. If you don’t take heed not only are you putting yourself, your horses and other road users at greater risk of accident, but you risk a fine if stopped and found to be contravening the law. In the event of an accident, your insurance will be also invalidated.

As a basic guide the unladen weight of the trailer, plus the weight of the heaviest horses to be towed must not exceed the trailer’s maximum authorised mass. This, in turn, should not exceed the car’s maximum towing weight.

So, first of all you need to find out:
  1. The combined weight of the two (or more, for multi-horse trailers) largest horses you wish to travel.
  2. The trailer’s unladen weight and maximum authorised mass (MAM).
  3. Your proposed towing vehicle’s maximum towing capacity (MTC).


First calculate the weight of your horses, then visit our towing vehicle calculator where trailer weights and towing vehicles’ maximum towing capacity weights can be found. However, if in any doubt please refer to your manufacturers’ handbooks.

If you would rather work this out manually the following rules, used in conjunction with one another, should help you work out whether your individual towing vehicle / horse trailer combination is suitable for carrying your horses:

X (combined weight of horses + unladen trailer weight) should be below or equal to trailer’s MAM

X (combined weight of horses + unladen trailer weight) should be below the towing vehicle’s max. towing capacity

Use our Towing Weights Calculator to help you work this out
IMPORTANT: Remember you need to allow for the weight of tack / feed / water when calculating the load as this will count toward the max. towing capacity figure. Therefore horses + trailer weight that equals exactly the car’s max towing capacity is still not legal!

How much does your horse weigh? Click here for a guide


Horses: 15hh m/w @ 500kg + 16.3hh TB @ 600kg = combined weight 1100kg
Trailer: Ifor Williams 510 @ unladen 1000kg; MAM 2700kg (fine with above horse combination)

Horses + Trailer gross weight = 2100kg

Vehicle: Mitsubishi Outlander with a Maximum towing capacity of 2000kg
This vehicle does not have the authorised towing capacity to tow the gross weight of the horses and the trailer.

Vehicle: Landrover Discovery with a maximum towing capacity of 3500kg
This vehicle is well within the capacity needed to tow these horses with this trailer.



So, you know the weight of your fully laden horse trailer and / or your towing vehicle's maximum towing weight, and the combination seems fine from a legal perspective. Before you hit the road, however, you should bear in mind the following:
  • Have you remembered to allow for extra weight that will be in the horse trailer, including tack and equipment, feed, water etc. in your calculations? All need to be added to the combined weight of your largest horses.
  • How close is the weight of your fully laden trailer (including above 'extras') to your towing vehicle's max. towing weight? If it's exactly on or just under it may sound legal, but from a safety perspective would be reckless. Allow a decent margin, i.e. at least a couple of hundred kilograms, to be safe rather than sorry.
  • 4x4 vs. normal cars - depending on how you use your horse trailer, it may be worth considering a 4x4 vehicle; this can be really helpful when trying to get onto & off muddy show grounds and for those horrible hill starts!
  • For extra stability while towing horse trailers, it may be worth considering purchasing a vehicle that has self-levelling rear suspension.

Tow Bar Heights & noseweight

For information on tow bar heights and nose weights click here

Down-plating your horse trailer

If you are intending to carry considerably less than your trailer’s MAM (i.e. travelling a single horse or two small ponies on a double horse trailer), it may be possible to get your trailer downrated by the manufacturer. This downrating will be reflected on the plate they return. It’s important to note that you must not carry a greater weight on the trailer than its new plate dictates, or you risk falling foul of the law.


Number plates

When towing a horse trailer you have a legal obligation to ensure that number plate displayed on the rear of the trailer matches that of the towing vehicle and is legible. It’s important to ensure you have a legal, reflective yellow plate fitted to the trailer as soon as you are able.

To order an additional number plate, you will need proof of ID (i.e. driving license) and your vehicle registration documents. Only the registered owner will be able to successfully order additional plates.



Last updated: 30/03/2011
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