After both running the final race of the 2018 season at Sonoma with Harding Racing, 2018 Indy Lights champion Patricio O'Ward and runner-up Colton Herta were announced to run the full season with the new partnership of Harding Steinbrenner Racing. However, on February 11, O'Ward and HSR parted ways after the team was unable to support a full-season program for O'Ward. O'Ward later moved to Carlin where he will drive the No. 31 car in 13 races, including the Indianapolis 500 as the team's third entry as Charlie Kimball will race the No. 23 car at the event.