We'll be renting a car in Ireland in June and I was going to go to AAA tomorrow to get my internation license.
While on the phone with the office I listened to a recorded informational piece about the permits and it said they aren't required per-se, and more of an aid when in a non-English-speaking country.
Are they required in Ireland? We'll be renting from EuropCar through Kemwel. The recording said it might be required by Hertz, but that was the only company specifically mentioned.
It's not very much money, but if I can pass on it I'd rather.
Your US drivers license is all you need. And as far as I know, that's the case at all the rental companies operating in Ireland & Northern Ireland.
Anyone with license not in English and not from an EU country should contact the rental company directly to find out requirements. The Canadians and Australians I know who have traveled to Ireland, haven't needed an International drivers license to rent a car as well.