The road system in Ireland has greatly improved over the last ten years. Although raod sizes are not comparable to Europe and USA they are adequate for the traffic volume. Please beware if travelling around Dublin on the M50 as recently they have introduced a barrier free toll system.
Irish motorists drive on the left hand side of the road and the following is Speed Limits
120 km/h (75 mph) for motorways
100 km/h (62 mph) for National Routes (Primary and Secondary) that are not motorway status.
80 km/h (50 mph) for local and regional roads.
50 km/h (31 mph) in built up areas.