Rahal seemed in control as the race entered its final stages but made contact with wall, enabling second-place runner Wilson to catch up and pass him on the backstretch.
Wilson went on to best Rahal by 4 seconds, securing his seventh career IndyCar win but his first on an oval track. His most recent victory came in July 2009 at Watkins Glen, N.Y.
Ryan Briscoe finished third, while James Hinchcliffe and J.R. Hildebrand rounded out the Top 5.
Scott Dixon led for much of the race but spun out on lap 173 and ended up in 18th place.
Will Power lost the lead after receiving a drive-through penalty for blocking Tony Kanaan, but still managed to widen his points lead to 36 over Dixon with the finish.