Since Iran is so much in the news these days, it is no wonder that one constantly hears, not only this proper noun, but its derived adjective (mis)pronounced by people in the media and those whose speech is influenced by such opinion makers, etc.
As in the case of Iraq, the pronunciation of Iran with a broad stressed vowel (as in the name Ron) is decidedly not in conformity with traditional English phonetics––British or American. It stems ultimately from the foreigner’s misplaced reproduction in English of the Persian vowel, which is then mimicked by native speakers who (unconsciously?) choose what they must imagine to be “authentic” over what would otherwise be dictated by native phonetics.
More to the point, the derived adjective Iranian, whose stressed vowel has always been [éi] (i. e., a diphthong) and not the monophthongal replica of the Farsi speaker’s un-English stressed vowel, is repeatedly heard from English speakers who have no knowledge of any foreign language, let alone Persian. This kind of phonetic solecism appears to be licensed by the very same desire for “authenticity” that manifests itself when speakers wish their interlocutors to evaluate them as being “in the know.”