Inspecting a used trailer, part by part

What to look at, in what order, and what each thing you find means for the price or for whether to buy.

This is the long version, for the day you go to see a trailer. Start with the plate: if that is wrong nothing else matters. Then work from the ground up.

In roadside checks of 3,083 light trailers in England, Scotland and Wales between 2019 and 2021, DVSA found that 1,530 (50%) had a defect serious enough for a prohibition, and 41% were given an immediate prohibition, meaning they could not be used again until repaired. Of the prohibitions, 36% were for lamps, 21% for running gear, which includes tyres, and 20% for brakes.

This is our own general advice, not legal advice. It does not cover what you may tow or how to tow it.

1. The plate and the serial number

DVLA says the number that identifies a trailer is usually on a metal plate fitted to it or stamped into the chassis. Look for both.

  • Read the number off the trailer yourself. A careful seller leaves the full number out of the advert so it cannot be copied onto another trailer, so the viewing may be the first time you see it.
  • Match every copy. The plate, the stamped number and the number on the seller's receipt should be the same. If they match, carry on.
  • If the plate is missing, loose or newer than the trailer, ask why. Grinding marks, fresh paint or a new weld where the number should be, with no good answer, is a reason to walk away. No discount makes up for a trailer you may not be able to show is yours.

2. Tyres and wheels

  • Find the date code. On the sidewall, at the end of the DOT marking, four digits give the week and then the year the tyre was made: 2319 is week 23 of 2019. Check the spare too.
  • Look for cracks, bulges and uneven wear. A trailer that stands for months can have tyres that look full but are cracked between the treads or across the sidewall. Old or cracked tyres are a cost to take off the price: count every tyre, spare included.
  • Uneven wear on one side. This can point to a bent axle or worn suspension. Ask about it, and treat it as more than a tyre cost until you know.
  • Spin each wheel. With the wheel off the ground, it should turn smoothly and quietly. A rumble, a grinding feel, or rocking when you pull the top of the tyre towards you points to worn wheel bearings: a repair to price in.

3. Brakes and the breakaway cable

If the trailer has brakes, the coupling head slides on a damper and there is a handbrake lever on the drawbar.

  • Apply the handbrake and try to push the trailer. It should hold. If it rolls, the brakes need adjusting at least, so ask when they were last looked at.
  • Push the coupling head in. It should move in against resistance and come back out. If it slides in with no resistance, or stays in, the damper is likely worn: a repair to take off the price.
  • Look at the breakaway cable. It should be there, in one piece, not frayed or knotted, with a clip that closes. A new cable costs little, but a missing or tied one tells you how the trailer has been kept.
  • On a trailer with no brakes, look for a secondary coupling. A chain or cable joining the drawbar to the vehicle. Check it is there and sound.

4. Coupling, drawbar and jockey wheel

  • Work the coupling lever. It should move freely and lock. If the head has a wear indicator, read it. A worn coupling head is a part to price in.
  • Look along the drawbar. Cracks, bends or a repair weld on the drawbar or where it meets the chassis are a reason to walk away unless the seller has a receipt for the repair from a workshop.
  • Raise and lower the jockey wheel. The clamp should hold it and the wheel should turn. A seized jockey wheel is cheap to replace.

5. Lights and wiring

  • Plug the trailer into your vehicle and try every lamp. Side lights, brake lights, both indicators, the fog light and the number plate light. Have someone press the brake while you watch.
  • Look at the plug and the cable. Green corrosion on the pins, or a cable chafed where it runs along the chassis, means rewiring rather than a bulb.
  • What it means. A lamp that does not work is usually a cheap fix and a reason to ask for a little off, not to walk away. Wiring chafed through along its length is a bigger job.

6. Chassis, suspension and floor

  • Look underneath. Rust on the surface is common. Rust that flakes away in layers, or holes, near the axle mounts or the drawbar, is a reason to walk away.
  • Push down on each corner. It should spring back evenly. A corner that sits lower or does not come back points to worn suspension.
  • Walk on the floor. Soft or rotten boards mean a new floor: a cost to take off the price, not usually a reason to walk away.

7. The paperwork to ask for

A trailer has no V5C and usually no official record of who owns it, so what the seller can show you is most of the proof you will get.

  • The receipt from when the seller bought it. It should name them and give the same serial number as the plate. Ask how long they have had it and where it came from.
  • Receipts for work done. Tyres, bearings, brakes and coupling parts, with dates. Each one is a cost from the list above you will not face soon.
  • No receipt and vague answers. If the seller cannot say where the trailer came from and has nothing on paper, we suggest walking away, whatever the price.
  • A receipt from them to you. Both names, the make, the model, the serial number, the price and the date, signed by the seller.

What the law says about selling an unroadworthy trailer

Under section 75 of the Road Traffic Act 1988 no one may supply a trailer in an unroadworthy condition, and supplying includes selling it, offering to sell it and showing it for sale. Unroadworthy means that using it on a road would break the rules on matters such as brakes, tyres and construction, or would put someone in danger of injury.

A seller has a defence if they had reasonable cause to believe it would not be used on a road in Great Britain until it had been put right. A seller doing this as a business must also show they took reasonable steps to make the buyer aware.

So if a seller tells you a trailer needs work before it goes on the road, get that in a message or on the receipt. This is a summary, not legal advice.

Sources

Each was read on 15 October 2026.