Deontay Wilder spent part of his Tuesday morning locked behind bars ... TMZ Sports has learned the star boxer was arrested in Los Angeles following a routine traffic stop.
Law enforcement sources tell us ... Wilder was pulled over in Hollywood at around 1:15 AM after LAPD officers claimed his Rolls-Royce's windows were illegally tinted and his license plate was obstructed.
During the stop, cops say they smelled an odor of burnt marijuana coming from his ride -- so they searched the car. Our sources say they then found weed and a 9mm in the vehicle, and put Wilder into custody.