After graduation, Tubbs coached for two years in Missouri high schools before taking a coaching job at the University of Wisconsin–Superior. He was in Wisconsin for nine years from 1922 to 1930, although he was only able to coach for five seasons due to attacks of Malta fever.
At Wisconsin–Superior, Tubbs served as both athletic director and a coach of football and hockey. He coached from 1923 to 1925 and again in 1928 and 1929, leading his school to football championships his last two seasons. Tubbs was a renowned inventor, developing improvements to athletic equipment such as a special inverted air valve for a football and elastic padding for football pants.
Tubbs resigned from Wisconsin–Superior in 1930 after another bout of health problems and moved to Miami, Florida. While he was recovering there in 1935, the head football coaching job at the University of Miami opened, and Tubbs was hired to coach the Hurricanes. Tubbs coached the Hurricanes for two seasons in 1935 and 1936, where he compiled an 11–5–2 record. In both seasons, his Hurricane teams bowed out as potential hosts for New Year's Day bowl games.
Tubbs was then hired as the 14th head football coach at the University of Iowa. He coached two seasons at Iowa in 1937 and 1938. He had a record of just 2–13–1 at Iowa, with his wins coming over Bradley and Chicago. Tubbs' tenure at Iowa is best distinguished by his coaching of players who would star for Iowa's 1939 team, nicknamed the "Ironmen". Some of the players Tubbs coached included Nile Kinnick, an all-Big Ten Conference selection in 1937, and Erwin Prasse, an all-conference end in 1938.