Class R Agricultural Trailers
What you need to know
This page offers information about class R agricultural trailers, their categories, regulations and technical details.
Trailer walkaround checks
Agricultural Trailer Walkaround ChecklistCarrying out a daily trailer walkaround check is an effective way to improve road safety and keep your trailer roadworthy. Agricultural trailers carry heavy loads and are regularly used on public roads so even a small defect can develop to become a serious hazard if it goes unnoticed. By taking a few minutes to check things like brakes, lights, reflective markings, tyres and that the trailer is correctly hooked to the tractor, you can spot issues before they cause breakdowns or collisions and help your trailer last longer.
An agricultural trailer - category R
Category R trailers are intended mainly to carry loads or to process agricultural materials; each trailer is supplemented at the end by an ‘a’ or ‘b’ index according to its design speed:
‘a’ trailers with a maximum design speed below or equal to 40 km/h
‘b’ trailers with a maximum design speed above 40 km/h.
For further information on trailer categories refer to EU Regulation 167/2013
| Trailer categories | Definition |
| R1 | Comprises trailers, the sum of the technically permissible masses per axle of which does not exceed 1,500 kg |
| R2 | Comprises trailers, the sum of the technically permissible masses per axle of which exceeds 1,500 kg but does not exceed 3,500 kg |
| R3 | Comprises trailers, the sum of the technically permissible masses per axle of which exceeds 3,500 kg but does not exceed 21,000 kg |
| R4 | Comprises trailers, the sum of the technically permissible masses per axle of which exceeds 21,000 kg |
General Rules
Roadworthiness testing
Class R agricultural trailers need to be tested if they are being used for commercial purposes.
Licensing and registration
Class R agricultural trailers do not need to be licensed or registered if towed exclusively by an agricultural tractor.
Weights and dimensions plate
Since 01 January 2016, all new agricultural trailers must be plated. If your trailer is not plated, you can contact your trailer’s original manufacturer or authorised distributor. Alternatively, you can contact an existing trailer manufacturer who may be willing to plate it for you. For further information Download and read our Revised Standards for Agricultural Vehicles.
Type approval
Type approval requirements for class R agricultural trailers are outlined in EU Regulation 167/2013 (as amended). For information on type approval, you will need to contact the National Standards Authority of Ireland (NSAI).
Braking requirements
Braking requirements depend on the year of manufacture. For trailers manufactured on or after 1 January 2016, the following are the braking requirements.
| Maximum design speed of trailer is 40 km/h and DGVW* is less than 5 tonnes | Design speed of trailer is over 40 km/h & DGVW* is 5 tonnes or more |
| Service Brake - minimum brake efficiency of 25% | Service Brake - minimum brake efficiency of 45% |
| Parking Brake - minimum brake efficiency of 16% | Parking Brake - minimum brake efficiency of 16% |
| Breakaway brake - minimum brake efficiency of 13.5% | Breakaway brake - minimum brake efficiency of 13.5% |
*DGVW is the design gross vehicle weight, also referred to MAM (maximum authorised mass) on the trailer's plate is the weight of a vehicle or trailer including the maximum load it can carry as per the manufacturer's design specifications.
- Trailers with a design speed of over 40 km/h that have been manufactured on or after 01 January 2016 must also be equipped with pneumatic braking systems including load-sensing capability.
- Trailers with a design speed of over 60 km/h that have been manufactured on or after 01 January 2016 must be equipped with anti-lock braking systems (ABS).
- Older trailers, provided they are designed to be drawn at speeds of 40 km/h or less can be fitted with a secondary coupling e.g., a chain or wire rope instead of a breakaway brake.
Trailers manufactured before 1 January 2016, the following are the requirements.
| Maximum design speed is 40 km/h | Design speed of trailer is over 40 km/h |
| Must be fitted with a service brake, a breakaway brake or fitted with a secondary coupling (consisting of a chain or wire rope) | Service Brake – 45% performance Breakaway Brake – 13.5% performance Parking – 16% performance |
Frequently asked questions
Trailers and trailed equipment are considered agricultural if they are mainly designed to be towed by a tractor. Other pieces of interchangeable towed equipment can also be classed as agricultural trailers e.g., slurry tankers, manure or fertiliser spreaders, grain chaser bins.
You will need to contact the original manufacturer.
No. Wood shavings are not classed as agricultural produce and therefore must adhere to the height limit of 4.65 m as well as all other weight, length and width limits outlined in legislation. See our Agricultural Vehicles Weights and Dimensions Leaflet
S.I. No. 248 of 2014 – Road Traffic Construction Equipment and use of Vehicles Regulations 2014
S.I. No. 354 of 2015 – Road Traffic Construction and Use of Vehicles Regulations 2014
S.I. No. 249 of 2014 - Road Traffic Lighting of Vehicles Regulations 2014
Please note that these regulations are in original format and amendments can be viewed at Irish Statue book
EC Regulation No. 167/2013 – Approval of Agricultural and Forestry Vehicles.