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Agri Machinery – Are You Legal?

20 December 2021

Over the last decade agricultural machinery has developed at a rapid rate. With machines constantly increasing in both size ad power, it is important that farmers keep on top of the rules and regulations surrounding their use. This publication aims to inform users of important legislative updates and ensure they are well informed to keep both themselves and other road users safe on the road.

Speed Limits for Agricultural Vehicles

The majority of tractors must adhere to the 25mph speed limit set. Some tractors are capable of doing up to 40mph (JCB Fastrac’s etc.) however, to do so certain criteria must be met. To legally travel at 40mph these vehicles must have –

  • Dual line braking (with 50% efficiency)
  • Full suspension to all tyres
  • High speed rated tyres

It is also important to remember that any trailers or implements towed by vehicles travelling at 40mph must also meet these standards to be capable of travelling safely at these speeds.

Vehicle Widths

The width of an agricultural vehicle also affects how it can be moved along the public highway. There are certain measures that must be taken and restrictions put in place based on the width of the vehicle/attachment. The following factors must be taken into account to legally move vehicles of the following widths along the road –


3.0 – 3.5mPolice Notification
Projections must be fitted to either side
Lights required at night and in poor visibility
Restricted to 20mph
3.5 – 4.0mAll of the above, but an escort vehicle must also be used
This escort vehicle must be in constant contact with the vehicle being escorted
Restricted to 12mph
Over 4.3mMust notify secretary of state


Front & Rear Overhangs

Many agricultural vehicles feature front and/or rear overhangs such as weight blocks for example. These must be made visible to other road users, with all sharp projections guarded or removed prior to travel. For overhangs over the following lengths, additional measures must also be taken –


<2.0mProjections must be visible from both the end and side
Sharp projections must be covered and/or removed
Lights required at night and in reduced visibility
2.0 – 3.0mMust add end marker boards
3.0m +Must add side marker boards
4.0m +Police Notification
>6.0m+Escort vehicle must be used
Additional side markers must be used


Vehicle Weights

The weight of an agricultural vehicle must also be taken into consideration to ensure it is capable of travelling legally. At present the maximum weight of an agricultural vehicle is 31 tonnes (tractor and trailer combined). The maximum weight which can be carried within a trailer is 18,290kg. Despite the fact that modern tractors are capable of towing more than this, legislation has not altered and as such still prohibits farmers from doing so.


It is also important to ensure that you hold the correct licence to operate agricultural machinery –

  • 16-year-olds can legally drive a tractor/trailer combination up to 2.45m wide, weighing up to 31 tonnes (providing they have sat and passed their tractor test)
  • Tractors can only legally be driven on the public highway displaying ‘L plates’ if travelling to or from a driving test. If the tractor has a passenger seat fitted, this must be filled by an appropriate companion who has held their licence for at least three years.
  • Once a Category B (car licence) is obtained, drivers are also permitted to drive tractors – despite never previously sitting a tractor test.
  • Other agricultural vehicles such as combines and forklifts are also covered by category B licenses, however, driver age and weight restrictions apply. 17-year-olds may drive vehicles within this category up to a maximum of 3.5 tonnes, whilst 18-year-olds can drive vehicles up to 7.5 tonnes and finally 21-year-olds may drive vehicles weighing more than 7.5 tonnes. It is important to remember that if pulling a trailer behind one of these i.e. combine and header trailer, that the driver must hold the appropriate +E licence.
  • Category F licences must be obtained to drive Agri forestry machinery
  • Category H licences must be obtained to drive track steered vehicles
  • Standard driving licences expire at midnight the day before your 70th birthday

Mobile Phones

Despite agricultural vehicles often travelling at slower speeds than most other road users, it is still illegal to use your mobile phone whilst driving on the public highway. It is also advisable to keep hands free usage to a minimum. Current fine for using a mobile phone whilst driving is £200 and six points.

Mud on the Road

Poor weather and challenging field conditions can often make it difficult for farmers to keep their machinery clean. It is however illegal to deposit mud on the road and care should be taken to try and dislodge as much mud from machines as possible before leaving the field. It is also good practice to display “Mud on Road” signs to warn other road users.

General Courtesy

Several considerations to keep in mind whilst travelling on the road are  

  • If possible allow traffic to pass – only when it is both safe and legal to do so
  • Do not use work lights / spot lamps whilst travelling along the road
  • Avoid travelling during rush hour – when and if possible

Common Sense

  • Vehicle lights should be fitted, working and regularly checked
  • Breaks should be regularly checked and maintained
  • Windows and mirrors should be kept clean
  • Be aware of blind spots and try to minimise these
  • Sharp projections must be covered and/or removed


  • All vehicles, trailers and implements must be maintained to standards set out in the manufacturer’s instructions
  • This can be done on farm or by an engineer, providing appropriate records are maintained

Top Tip – Carry out daily checks of tractors and machinery before use – this allows any problems to be identified and corrected at the earliest possibility.



Q – If I am stopped by the police whilst towing a trailer fitted with box pushers, am I obliged to turn the vehicle off?

A – No, if the police stop you whilst towing a load secured by box pushers, it is recommended you do not turn the tractor off. Turning the tractor off will cause the oil pressure to drop and the pushers to release which may result in you being charged with towing an unsafe load.

Q – If I am towing a trailer loadened with a single layer of potato boxes (which are held in place using box pushers) do I also need to use straps?

A – No, if box pushers are used no straps are required. If no box pushers are in place, each box must be individually strapped.

Q – If it is not possible to remove spikes before travelling on the road, how do you recommend covering them?

A – Complete removal would be best, however, homemade covers using a length of flat bar / angle iron can also be used to cover the points of spikes and create a bumper plate along the front of the loader.

Q – How would you recommend positioning your front loader whilst traveling on the road?

A – Ideally, spike removal prior to travelling on the road would be preferable. Avoid travelling with your loader in the air, as it alters the tractors centre of gravity – which can impact stability. Similarly, loaders must be carried at a height which they will cause minimal damage to traffic if a collision were to occur. Keeping forks/spikes turned inwards and using the loader as a bumper is the best option.

Q – Do bales need to be strapped onto trailers?

A – All trailers carrying bales should have straps over every row- regardless of whether they are wrapped or straw bales.

Q – How can you safely secure fertiliser bags for transport?

A – Fertiliser bags are notoriously difficult to strap down as they settle in transport, causing ratchet straps to slacken. Using a sheet and rope is probably the best method of holding fertiliser bags in place.

Q – Can all pickups legally tow 3.5 tonnes?

A – No all pickups cannot legally tow up to the 3.5t maximum limit. All vehicles have different towing limits, with VIN (vehicle identification) plates fitted which detail permitted maximum gross weights.

Q – Is there a limit to how many miles can be travelled on red diesel?

A – No, there is no mileage limit as to how many miles can be travelled as long as they are for agricultural purposes.

Q – Is the “Tilly your Trailer” test to be recommended?

A – PURE regulations say all trailers should be maintained to a good standard however, Tilly you Trailer provides additional reassurance that your machinery is in a safe, working order.




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