Weights and Dimensions

  • Changes to the Weights, Dimensions & Coupling Requirements for Agricultural Vehicles.


From a road safety perspective, and also to protect Ireland’s road and bridge infrastructure, it is imperative that vehicles (including agricultural vehicles) adhere to specified weights and dimensional limits.

As a result national weight limits are being introduced for agricultural trailers. These limits will depend on the number of axles fitted, the spacing between them and the type of coupling fitted. A revised width requirement is also being introduced for agricultural trailers, which aligns with that applicable to heavy goods trailers.

These revised standards take effect from 1st January 2016 for both new and existing agricultural vehicles.

Summary of Revised Weights, Dimensions & Coupling Requirements for Agricultural Vehicles

A summary of the revised standards is as follows:


National weight limits of 18 and 24 tonnes are being introduced for two and three axle agricultural tractors respectively, with limits of 13, 19 and 22.5 tonnes being introduced for rigid drawbar (i.e. unbalanced) single, tandem and triaxle agricultural trailers respectively.

Higher limits of up to 24 and 34 tonnes are being introduced for unbalanced tandem and triaxle agricultural trailers respectively that meet certain additional requirements:

  • they must be plated,
  • they must be fitted with a flexible suspension system,
  • they must be fitted with flotation tyres for operation at 10 tonnes per axle in the case of a tandem axle trailer or 9 tonnes per axle in the case of a triaxle trailer, and finally
  • they must be fitted with a steered or steering axles if they have an axle spacing of 1.8 metres or greater.

Further details are available here .

Combinations of agricultural tractors and trailers, where either of them is unplated, will have their maximum towable mass capped at 3 times the tractor’s unladen weight.


The following dimensional limits will apply to agricultural vehicles from 1 January 2016.

  • Length = 12 metres (or 18.75 metres when combined – for example –
    with a tractor and trailer or other interchangeable towed equipment).
  • Height = 4.65 metres. However, trailers used to transport loads of
    baled agricultural produce such as hay or straw, and so on are exempt
    from this height limitation.


  • Widths
  •  Agricultural tractors and trailers
    Width = 2.55 metres.
  •  Large tractors – tractors whose unladen weight exceeds 7.25 tonnes
    Width = 2.75 metres.
  • Tractors with flotation tyres or dual wheel systems
    Width = 3.5 metres.
  • Fully mounted equipment and interchangeable towed equipment
    Width = 3.0 metres.
  • Self-propelled agricultural machinery
    Width = 3.5 metres.

However, self-propelled agricultural machinery can be wider than 3.5 metres so long as when travelling on public roads it has an escort vehicle. This escort vehicle must drive in front, use dipped headlights and carry working flashing amber beacons and a “CAUTION –WIDE LOAD FOLLOWING” sign. The machinery being escorted must also carry flashing amber beacons, one of which must be visible to the rear and display a “WIDE LOAD” sign to the rear.

Note: The following items don’t count when measuring the overall
width of an agricultural trailer:

  • the part of flotation tyres and mudguards protruding beyond the bodywork,
    up to a maximum of 100 millimetres on each side of the vehicle, and
  • devices associated with hydraulic rear door opening mechanisms.  


Requirements are also being introduced for the maximum vertical load that can be exerted on an agricultural tractor’s coupling by a trailer’s drawbar. This vertical load must not exceed:

  1. the lower of the tractor or trailer manufacturer’s specifications,
  2. 3 tonnes, or
  3. 4 tonnes in the case of a ball and spoon type coupling which has been approved and plated for this load.

Some practical advice, including tips on achieving compliance with the new requirements, is contained on our list of weights and dimensional related “Frequently Asked Questions”