The Road Safety Authority (RSA) identified 49 tractors with "major or dangerous defects" in the first ten months of 2025, latest statistics show.
According to the RSA only tractors that are used in a commercial capacity are required to be tested once they are four years old.
Under current requirements an agricultural tractor does not need to be roadworthiness tested, however farmers are "legally required" to make sure that the vehicle is in a roadworthy condition at all times when it is used on a public road.
All tractors must also be fitted with a flashing amber beacon and have it switched on when operating on any public road.
During the ten months to October the RSA said that 69 tractors were inspected "at roadside" and out of these 49 were identified with major or dangerous defects.
According to the RSA the number one major or dangerous defect identified was in relation to "stop lamps".
The next was tyres while the third was steerling linkage condition.
Under the current rules fast tractors must undergo a roadworthiness test and display a certificate of roadworthiness (CRW).
A fast tractor is defined "as a wheeled tractor in category T with a maximum design speed exceeding 40 km/h".
According to the RSA, however, fast tractors do not have to undergo a roadworthiness test if it is used for the "purposes of agricultural, horticultural, forestry, farming or fishery activity" solely within the state and mainly on the land where such activity takes place - including agricultural roads, forestry roads or agricultural fields or is used on a small island.
Meanwhile the RSA has also confirmed that a total of 43 tractors were inspected a at Commercial Vehicle Roadworthiness testing centre in the nine months to the end of September 2025.
Inspectors failed 16 of these tractors and also highlighted that one of these failed because of "dangerous" defects.
Separately according to the Health and Safety Authority (HSA) tractors and machinery collectively are the "main cause" of fatal accidents in agriculture in Ireland.