Sections of the Tullamore bypass have failed skid-safety tests.
Offaly County Council confirmed that surface resistance at certain areas, including side roads and roundabouts, was not up to standard.
As a precaution, contractor PT McWilliams is erecting signs advising motorists to 'Drive with Care'.
In an interview with Midlands 103, director of services with the local authority Frank Heslin said: "We've contracted and paid to get a very high-standard road…We've asked the contractor to ensure that does happen."