Trailer Requirements

v1.0 1st January 2015

This document provides information on relevant law and helpful advice relating to glider trailers. The information was relevant to glider trailers at the time of original publication. Although the guide is updated from time to time, drivers are urged to ensure that they are aware of and comply with current regulations.


  1. The Law
  2. Good Driving and Towing Practice
  3. Insurance
  4. Towing Abroad
  5. Trailer Maintenance
  6. More information

1. The Law.

The law is complex. The construction and use of trailers is covered by the Road Vehicles (Construction and Use) Regulations 1986 and Road Vehicles Lighting Regulations 1989 as amended by over 100 UK amendments and EU Directives. In addition various Road Traffic Acts and Driving Licence Regulations add to the complexity.

Trailer Length and Indivisible Loads

The legality of glider trailers exceeding 7 metres length being towed by private cars is occasionally misunderstood by insurers and others. In July 2012, the governments VOSA clarified the situation for the BGA, noting why glider trailers exceeding 7 metres in length can be towed by private cars and vans.

A glider wing or fuselage is considered to be an indivisible load if it cannot practically be divided into two or more sections. A table in Regulation 7 of the Road Vehicles (Construction and Use) Regulations 1986, as amended, contains the details of the maximum length permitted for various sorts of vehicle and trailer combinations. Item 9 of that table does normally restrict a trailer towed by a vehicle which is not a goods vehicle over 3500 kg GVW to a maximum length of 7m not including the towing hitch arrangements. However regulation 7 (3A) (a) dis-applies the requirements of that table in a number of areas including where a trailer is constructed and normally used for the conveyance of “indivisible loads of exceptional length”. In this context “exceptional length” means longer than the regulations would normally permit. This exception would permit a trailer of perhaps 11m length specially constructed to carry indivisible loads such as a glider to be towed by a car or other vehicle which is not a goods vehicle over 3500 kg GVW. Note however that Regulation 7 (5) (b) still limits the length of (i) the towing vehicle to a maximum of 9.2m; and (ii) the length of the towing vehicle and trailer combination to a maximum of 25.9m unless special police notification, escorting and attendant requirements are complied with.

Understanding the Terminology

  1. a) Weights are given in kgs, where 1000 kgs is equal to 1 Metric Tonne (within 2% of an Imperial Ton). Lengths are in millimetres and metres.
  2. b) For vehicles and trailers, the Maximum Authorised Mass (MAM) is the maximum loaded weight of the vehicle or trailer permitted by the manufacturer. For cars and commercial vehicles, it is given on the Vehicle Identification Number (VIN) Plate or in the Manual. For trailers it must be displayed on a marking plate affixed to the near side of the draw bar or A-frame. (It is NOT the ACTUAL loaded weight of the vehicle or trailer that counts but the manufacturer’s permitted maximum weight – i.e., the design maximum for the trailer and its load. Some trailers built for 15 metre single seat gliders have a MAM of less than 750, which is a key dividing point; many are over that value. Open class and two seat glider trailers all exceed 750 MAM.)
  3. c) You may find reference in some documents to GVW (Gross Vehicle Weight) or to MTPLM (Maximum Technically Permitted Laden Mass). For all practical purposes these are the same as MAM.
  4. d) The Vehicle Unladen Weight (VUW) is defined as the empty weight excluding fuel, water and loose tools and equipment. Remember that the addition of a tow bar will add significantly to the VUW.
  5. e) The Kerb Weight is NOT the same as the VUW. It is usually given in the manual and is normally defined as the empty weight plus a full tank of fuel and 75Kg allowance for the driver (but check as definitions do vary between manufacturers).
  6. f) The Maximum Train Weight (MTW) is the maximum allowed sum of the towing vehicle and trailer actual weights, defined by the tow vehicle manufacturer. It is defined on the tow Vehicle Identification Plate where specified. For cars, there will also be a defined maximum trailer actual weight.
  7. g) The Maximum Combined Weight is NOT the same as the MTW. It is the maximum sum of the MAM of the towing vehicle and the MAM of the trailer permitted by the driver’s licence (i.e., it is defined by MAMs and not actual weights).
  8. h) The length of a trailer excludes the draw bar or A-frame; these are also excluded in defining the front of the trailer.

Driving Licence

A driver must have a driving licence valid for the tow combination. Do not assume that this will be the case, especially if the driver qualified after 1.1.97 or is over 70.


  • Vehicles and trailers are not permitted to use the outside lane of a three lane carriageway, except to overtake an exceptional load spanning two lanes.
  • Maximum speeds apply to trailers that may be different than for other road users.
  • Passengers are forbidden in trailers.
  • There is no Road Tax on private trailers.
  • An MOT is not required for private trailers.
  • The trailer must display the same number plate at the rear as the towing vehicle.
  • The towing vehicle must be fitted with an audible warning device which sounds when the direction indicators are used.
  • After 01.01.98, any tow vehicle (except commercial vehicles and motor-caravans) which was first marketed after 01.01.96 can only have EC Type Approved and tested tow bars fitted.
  • Trailer contents must be properly secured, other than remaining in place by their own weight, so as not to present a hazard to other road users and pedestrians.
  • Google search ‘road trailer requirements’ to identify a number of helpful online government info resources.

 2. Good driving and towing practice

Although not necessarily legal requirements in the UK, the following driving practices are highly recommended by motoring organisations and therefore by the BGA.

  1. You should not tow a trailer that exceeds either the tow vehicle manufacturer’s recommended towing weight or tow hitch nose weight. Doing so could invalidate both vehicle warranty and vehicle and trailer insurance. Recommended practice for braked trailers is not to exceed 85% of the kerbside weight of the towing vehicle.
  2. Snaking – if the combination starts to snake, NEVER brake hard. Slow down gradually and carefully, releasing the accelerator and then using the gears to slow. Hold the wheel firmly and steer straight ahead, and never into or against the snake. Bad snaking normally means that there is insufficient nose weight on the tow ball.
  3. Stabilisers should only be used in accordance with the manufacturer’s instructions and should be checked annually.
  4. Emergency braking can cause the trailer to ‘jack-knife’. Avoid the need by keeping a safe distance behind other vehicles.
  5. The driver should have ready access to a warning triangle (preferably two – place one behind and one in front of the combination when stopped, especially on single carriageway roads), a First Aid Kit, spare bulbs and high visibility jacket (all compulsory in many other EU countries).
  6. Modern glider trailers add up to 5 side/marker lights on each side and can overload the fuse capacities of the towing vehicle. Always carry spare vehicle fuses, but check, before upgrading a fuse, that you will not overload the tow vehicle’s wiring.
  7. The tow combination should have dipped headlights at all times, except where doing so would dazzle other drivers.
  8. Although not a legal requirement, it makes good sense (in the UK, but not in all countries) to affix a ‘Long Vehicle’ label to the rear of a glider trailer, especially so if you are towing with a long vehicle such as an estate car or motor caravan. Ensure that you check the legality of such signs.
  9. Ensure you can monitor the trailer wheels through the wing mirrors, especially on single-axle trailers, so that a puncture does not become a catastrophe. For peace of mind, you can have the trailer tyres injected with a gel that automatically seals punctures.
  10. Unless you have taken the extra driving licence towing tests, you should practice and become competent at reversing with a glider trailer attached before towing one on public roads.
  11. Do not park a trailer for long periods with the hand brake applied to avoid the brake linings forming a rust bond and sticking fast to the inner surface of the drum. Use wheel chocks instead.

3. Insurance

  1. The increasing prevalence of fraudulent insurance claims has forced insurance companies to increase significantly their scrutiny of claims. As a result, you could well find your claim being rejected or the payment reduced if any aspect of your vehicle, trailer or load are not fully compliant with the law. Most insurance policies also include a clause requiring you to keep the insured property in good repair.
  2. Most tow vehicle insurance policies provide Third Party cover for an attached, towed trailer; this insures you for injury or damage caused by the trailer to third parties. However, since a glider trailer may be regarded as exceptional by some insurance companies, you are urged to check before you tow.
  3. Damage cover for the trailer and its contents requires a separate insurance policy.
  4. Be aware that many vehicle insurance policies now include a restriction clause removing all cover when the vehicle is ‘used in or on restricted areas of airfields or airports’, whether or not you are towing a trailer. You may thus be personally liable for any injury or damage accidents in these areas and you are strongly advised to find insurance without this exclusion.
  5. All trailer owners are urged to check that their trailer is roadworthy and complies with the relevant rules before setting out, otherwise insurance may be invalidated.
  6. If you have some form of recovery insurance on the tow vehicle, check that it covers your trailer. (In practice few recovery organisations will have vehicles able to carry a glider trailer.)

4. Towing abroad

  1. Any vehicle or trailer which complies with UK legislation can be imported temporarily (6 months maximum in any 12 months) into another EU country without having to obtain local type approval. However, it must comply with local law where this differs from UK law, for example in respect of vehicle lengths, widths, heights and weights. Not all aspects of vehicle construction, use and lighting have yet been harmonised across the EU (the process is currently under way) so you are advised to check before travelling – see (g) below. In particular, the rules and their interpretation regarding side and rear marking of long trailers seem to vary from state to state.
  2. Speed limits when towing vary enormously between different EU countries and in some countries such as France it is common to find sections of peages, autoroutes and many rural roads signed for both solo vehicles and trailers with both higher and lower limits than those that apply generally. If you see a sign with a caravan pictogram, it is best to assume it also applies to you and your glider trailer. Note that many EU countries impose ‘on the spot’ fines for exceeding speed limits and may impound your vehicle if you are unable to pay. French police, amongst others, have become particularly active with surreptitiously placed mobile speed cameras.
  3. Most countries also have a minimum speed on motorways – if you cannot maintain this minimum (eg on hills), you must stay in the innermost lane.
  4. It is an offence in most Continental countries to carry any form of equipment that detects the presence of speed cameras, though passive equipment such as a location warning on a SatNav system is normally acceptable. It is also an offence to indicate the presence of speed cameras to other motorists.
  5. Take with you your driving licence, vehicle registration document and insurance certificates (tow vehicle and trailer).
  6. Check that you are properly insured. Many UK car policies now restrict cover outside the UK to just the statutory minimum Third Party cover unless an extra premium is paid. Many also have limits as low as 14 days on the length of individual trips. Note that an Insurance Green Card is no longer necessary in EU countries, but check with your insurer. Your insurer can supply a Bail Bond for Spain.
  7. The motoring recovery organisations and the Caravan Club are excellent sources of information on regulations for tow combinations abroad and, if you are taking your trailer abroad, you are strongly recommended to check whether any special requirements apply to trailers of exceptional length, such as a glider trailer.

 5. Trailer maintenance

Glider trailers are used for long journeys infrequently, so should be checked before any off-airfield journey. If you always rig your glider without moving the trailer, it is especially important to check that the trailer is ready for a retrieve.

Trailer tyres generally degrade from UV damage before they wear beyond safe limits. As such tyres need to be checked regularly for overall condition – not just tread wear.

Regular maintenance may avoid a retrieve mishap.

6. More information

Road Traffic Act 1991

Govt info – towing a trailer with a car (updated 10 Sep 21)