Hitching, lights and number plates

By the end of this topic you can

• You can couple and uncouple a light trailer in a safe order.
• You can attach a breakaway cable or secondary coupling correctly.
• You can list the lights a trailer must have and check they work.
• You can say when a trailer needs a number plate.
• You can check trailer tyres against the legal minimum.

What you need to know and understand

• Most cars use a ball-type coupling; a secondary coupling such as a chain or wire rope keeps the trailer attached if the main coupling fails.
• Trailers over 750 kg must have a breakaway brake that stops the trailer if it comes off; some older trailers of 1,500 kg or less built before 2016 may use a secondary coupling instead.
• The RSA recommends attaching the breakaway cable to the towing structure, or looping it round the tow ball where there is no proper point.
• Trailers must have red rear lamps, red stop lamps, amber indicators, rear red reflectors and number plate lighting; trailers over 1.6 m wide also need white front position lamps.
• A trailer needs a number plate with the towing vehicle's registration unless its DGVW is under 750 kg, and any trailer that hides the car's plate must carry one.
• Trailer tyres must have at least 1.6 mm of tread; the RSA recommends at least 3 mm.
• A tow bar used for towing must have a working power socket.

Coupling up, step by step

To uncouple, reverse the order: trailer handbrake on, chock the wheels if on a slope, lower the jockey wheel, unplug the electrics, remove the breakaway cable, then release the coupling and lift it off the ball.

1. Park on firm, level ground with the trailer handbrake on.
2. Reverse slowly until the tow ball is just under the coupling head. Use a helper standing to the side, never between car and trailer.
3. Lower the coupling onto the ball with the jockey wheel until it locks. Check the indicator if there is one, and lift the A-frame slightly to prove it is secure.
4. Attach the breakaway cable or secondary coupling.
5. Plug in the electrics, making sure the cable has enough slack for turning but cannot drag on the road.
6. Raise the jockey wheel fully and lock it, then release the trailer handbrake.
7. Check every light with a helper or by looking at reflections in a window.

Lights and plates on the road

Your trailer's lights tell drivers behind what you are doing, because the trailer hides the car's own rear lights. Replace any cracked or broken lens and keep lights clean.

Reversing lights are compulsory on all new trailers built since 29 October 2012, and on trailers over 750 kg under the UN-ECE lighting rules. They are optional on older trailers of 750 kg or less.

Number plates must be visible at all times. If your trailer blocks the car's plate, fit a plate to the trailer showing the car's registration.

Common mistakes

• Standing between the car and trailer while someone reverses. Stand to the side where you can be seen.
• Not checking the coupling has locked. Lift the A-frame slightly or check the indicator every time.
• Leaving the jockey wheel partly down. It can hit the road and damage the trailer.
• Forgetting the breakaway cable, or clipping it where it cannot work. Attach it to the towing structure.
• Setting off without a light check. Faulty connections are common, so check every trip.

Test yourself: Hitching, lights and number plates

Answer each question, then read the explanation. Questions come in a random order each time.