On April 16, 1895, Detroit’s baseball club was called the Tigers for the first time in an article by Phil Reed in the Detroit Free Press.
Source : Historical Society of Michigan
Note : The Main Library now provides the MSU community online access to the historical Detroit Free Press from 1858 through 1922. Can you find an article called “Their First Breather : Strouthers’ Tigers showed Up Very Nicely. The Men are Fast, and Bat and Field Acceptably”, Detroit Free Press, April 16, 1895?
Also see Zlati Meyer, “Detroit baseball team 1st called Tigers in 1895 Freep”, Detroit Free Press, April 12, 2015.