A six-axle artic loads steel coil at a yard outside Dublin, weighs in at 45.5 tonnes, and runs to Rosslare for the Fishguard ferry. In Ireland that is a legal load. Four hours later on the A40 it is 1.5 tonnes over the UK ceiling. Ireland’s weight framework is the UK’s with the numbers turned up a notch on the heaviest combinations, and that is where UK fleets working both sides of the Irish Sea get caught: not going in, coming back.
Irish limits come from the Road Traffic (Construction, Equipment and Use of Vehicles) Regulations 2003, SI 5 of 2003, as amended, and are summarised in the RSA weights and dimensions leaflet. Most ceilings come in two figures, a base figure and a higher one that applies when the vehicle has air suspension, twin tyres, or (for the heaviest combinations) EBS and ESC.
| Configuration | Ireland | UK equivalent |
|---|---|---|
| 2-axle rigid | 16 t, or 18 t with axle spacing of 3 m or more | 18 t |
| 3-axle rigid | 25 t, or 26 t with air suspension and twin tyres on the drive axle | 26 t |
| 4-axle rigid | 30 t, or 32 t with the specified suspension and tyres | 32 t |
| 2+2 articulated | 35 t, or 38 t with air suspension | 38 t |
| 2+3 articulated | 40 t, or 42 t on intermodal work | 40 t |
| 3+3 articulated | 40 t, 44 t, or 46 t with EBS and ESC | 44 t |
| Drawbar, 3+3 or 4+2 | 46 t | 44 t |
Axle limits line up with the UK: 10 tonnes on a single non-driving axle, and a drive axle of 10.5 tonnes, or 11.5 tonnes with air suspension and twin tyres. Tandem groups run from 11.5 to 20 tonnes depending on spacing, tri-axle groups 21 or 24 tonnes. Maximum height is 4.65 metres including the load.
The Irish regulations give the higher figure only to vehicles with the listed equipment, and enforcement officers check the plate and the suspension, not the driver’s word. A UK 6-axle artic on air suspension with EBS and ESC qualifies for 46 tonnes in Ireland on paper, but its UK plating and the UK ceiling still apply the moment it lands at Holyhead or Fishguard. Operators running Irish domestic work on UK-registered trucks tend to plate to 44 and stay there, because the two-tonne Irish bonus is not worth a UK prohibition.
The 42-tonne 2+3 figure is narrower than it looks. It applies to intermodal movements, a container or swap body moving to or from a port or rail terminal, and the RSA leaflet ties it to that use. A 2+3 artic on general haulage stays at 40.
The Garda National Roads Policing Bureau runs roadside enforcement, with the Road Safety Authority setting the rules and running the commercial-vehicle inspection regime. Checks cover weight, tachograph, vehicle condition and documents in the same way DVSA checks do. Ferry ports see the most inbound HGV attention, because that is where the traffic concentrates; Dublin Port and Rosslare between them handle nearly all UK-Ireland roll-on roll-off freight.
The land border with Northern Ireland is open and unchecked, so a truck can be under Irish rules on the M1 and under UK rules on the A1 ten minutes later. The two frameworks differ only at the top of the weight table, which is one reason cross-border operators in the north-east keep to 44 tonnes regardless of which side they loaded on.
Penalties for overweight vehicles in Ireland are set by the Road Traffic Acts and enforced through fixed charges and, for larger excesses, court prosecution. The bands and amounts change, so the RSA page is the place to check current figures rather than a third-party summary.
46 tonnes, for a 3+3 articulated combination fitted with EBS and ESC, or for qualifying drawbar combinations. Without that equipment the 3+3 limit is 44 tonnes, and 40 tonnes without air suspension. The figures are in the RSA weights and dimensions leaflet and SI 5 of 2003 as amended.
No. Both Ireland and the UK allow 11.5 tonnes on a drive axle with air suspension and twin tyres, and 10.5 tonnes without. The difference between the two countries is at the gross-weight end, where Ireland allows up to 46 tonnes on combinations the UK caps at 44.
No. Northern Ireland is under the UK framework, the Construction and Use Regulations 1986 and the Authorised Weight Regulations 1998, with a 44-tonne top limit. The Republic runs its own 2003 regulations with a 46-tonne top limit. The border is open, so one trip can fall under both.
Only if it is plated for it and equipped with EBS and ESC, and even then the UK’s 44-tonne limit applies as soon as it returns. In practice UK operators working both sides stay at 44.
Overloading is an offence under the Road Traffic Acts, dealt with by fixed charge for smaller excesses and prosecution for larger ones. Current amounts are published by the RSA and change from time to time.
The 46-to-44 problem is a loading-bay problem. The truck is legal when it leaves the Irish yard and the driver has no reason to look for a weighbridge before the ferry. An in-cab read taken as the last coil goes on shows the gross and per-axle figures in 10 kg steps against whichever limit the run is planned to, and for a UK-bound trip that limit is 44. On a trailer swap at Dublin Port, iWeigh for Tractor Units / Trailers pairs the tractor with the trailer it has picked up and shows the combined weight without the driver doing anything, which is the moment an Irish-loaded trailer meets a UK-bound tractor.
Ireland is an EU member state, so it is inside the EU’s move toward on-board mass-monitoring for heavy goods vehicles, which the Council’s December 2025 position would apply to zero-emission vehicles from December 2029. The EU on-board mass-monitoring explainer covers what is proposed and where it stands.
For the UK side of the crossing, see what HGVs can legally weigh on UK roads. For the five-country comparison, the Europe hub.
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