On October 9, 1970, Coleman was part of a multi-player deal that sent Coleman, Ed Brinkman, Jim Hannan and Aurelio Rodriguez to the Detroit Tigers in exchange for Denny McLain, Elliott Maddox, Norm McRae and Don Wert. On March 27, 1971, Coleman was knocked unconscious by a line drive hit by Ted Simmons of the St. Louis Cardinals during a spring training game. Coleman sustained a linear skull fracture, was hospitalized for two weeks, and remained on the disabled list for 21 days before joining the Tigers in May 1971. Coleman had a 7–6 record on July 4, 1972, but he finished the season with a 13–3 record from that point forward. During the 1971 season, Coleman compiled a 20–9 record and a 3.15 ERA while recording 16 complete games. His 236 strikeouts in 1971 was a career high and ranked third in the American League behind Mickey Lolich and Vida Blue.