Tractors on public roads
A tractor on a public road follows the same Highway Code as everyone else, but it also has its own speed limits, width rules and warning-light rules. These exist because tractors are slow, heavy and often much wider than a car.
This page explains the main rules for driving a tractor on roads in Great Britain. If you are new to the road itself, the car topics on speed limits and road signs are a useful starting point.
By the end of this topic you can
- You can state the normal maximum speed for most tractors and when a higher speed is allowed.
- You can explain how a tractor's width affects its speed limit and journey planning.
- You can say when a flashing amber beacon must be used.
- You can describe how to avoid holding up a long queue of traffic.
- You can check width and weight before setting off with a trailer.
What you need to know and understand
- Most tractors may travel at up to 40 km/h, which is about 25 mph.
- Higher-specification tractors may go up to 40 mph if they meet extra standards such as all-wheel suspension, better braking, a speedometer and a horn.
- Wider agricultural vehicles have lower limits: 20 mph between 2.55 and 3.5 metres wide, and 12 mph between 3.5 and 4.3 metres wide.
- Width includes the tyres and any towed implement or trailer.
- Vehicles wider than 3 metres must notify the police of their journeys, and those wider than 3.5 metres also need attendants.
- A vehicle with a top speed under 25 mph must show a flashing amber beacon on an unrestricted dual carriageway.
- A tractor and trailer combination has a 31 tonne maximum, and the trailer alone 18.29 tonnes.
- Highway Code rule 169 says you should not hold up a long queue of traffic, especially in a large or slow vehicle.
How fast can a tractor go?
For most tractors the limit is 40 km/h, roughly 25 mph. A tractor built to a higher standard can be used at up to 40 mph, but only if it has the required equipment, including all-wheel suspension, a set level of braking efficiency, pneumatic tyres, a speedometer and a horn. Never assume a tractor qualifies; check its paperwork.
Road speed limits still apply on top of this. If the road limit is lower than the tractor's own limit, the road limit wins.
Width changes everything
Modern tractors on wide tyres can be wider than you think. Once the vehicle, including tyres and any trailer or implement, is more than 2.55 metres wide, the limit drops to 20 mph. Over 3.5 metres it drops to 12 mph. Many larger tractors fall into the 20 mph band, so measure before you go.
- Over 3 metres wide: tell the police about the journey before you travel.
- Over 3.5 metres wide: you also need attendants to escort you.
- Plan a route that avoids narrow lanes, low bridges and weight-restricted roads; watch for the signs that warn of them.
Beacons, lights and signals
Highway Code rule 225 says slow vehicles such as tractors must use a flashing amber beacon on unrestricted dual carriageways. The beacon can be on the tractor or on the trailer, as long as it can be seen. Using one on other fast roads helps drivers spot you sooner.
Signal early and clearly. A long tractor and trailer swings wide on turns, so drivers behind need time to understand what you are doing. Keep lights, indicators and reflectors clean, especially after field work.
Letting traffic past
Do not wave drivers past. You cannot be sure the road ahead is clear for them, and they are responsible for their own decision to overtake.
- Check your mirrors often for a build-up of traffic behind you.
- Look ahead for a safe place to pull in, such as a lay-by or a wide gateway.
- Signal, pull in fully and stop if needed so drivers can pass safely.
- Check mirrors again before signalling and moving off.
Common mistakes
- Measuring only the tractor. The width that counts includes tyres and any trailer or implement.
- Treating 25 mph as a target on narrow lanes. Drive at a speed that lets you stop in the distance you can see.
- Forgetting the beacon on an unrestricted dual carriageway. It is a legal requirement for vehicles that cannot reach 25 mph.
- Leading a long queue for miles. Pull in where safe and let traffic pass.
- Waving drivers past. Leave the overtaking decision to them.
Test yourself: Tractors on public roads
Answer each question, then read the explanation. Questions come in a random order each time.
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Sources: Tractors and regulatory requirements: a brief guide (gov.uk); Highway Code rules 164, 169 and 225 (gov.uk). Independent guide, not affiliated with any licensing agency. Always check the latest official rules with the DVSA.