Paul Glatzel, Harry Smith and Kabongo Tshimanga scored from the 87th minute onwards as Tranmere finished with nine men.
Newport took a deserved lead through Shane McLoughlin’s 11th-minute penalty before Hakeeb Adelakun levelled from the spot after the half-hour mark.
Rumarn Burrell bagged the opener in the 10th minute, with former Royals striker Jon Dadi Bodvarsson making it two. It looked like goals from Michael Craig and Sam Smith would earn Reading a point ...