After the war he attended the University of Nebraska-Lincoln where he was a member of the Society of Innocents and Beta Sigma Psi fraternity.

After returning to the U.S., Tiemann served three terms as mayor of Wausa, Nebraska.

He successfully pushed for a number of progressive changes, including the adoption of a new tax structure and of new programs of state financial aid to education, the expansion of the University of Nebraska, and the enactment of the state's first minimum wage law and of open-housing legislation.

From June 1, 1973, to January 1977[5] he served as Head of the U.S. Department of Transportation's Federal Highway Administration.

[6] Tiemann died at his home in Dallas, Texas, on June 19, 2012, aged 87.