It's hard to miss the Nimbus brewery location as you drive by 6464 E. Tanque Verde: this mural fills almost half of the front of the building!
Update (June 19, 2016): I'm pretty sure the artist was Rock Martinez. I saw a Nimbus Brewing mural mentioned as I was updating our article Rock Martinez in the Tucson Citizen, 2008.
Update (April 15, 2019): I hear that this mural is gone. Google Maps shows a medical office there.