I have a 2018 Sierra for less than a week, took it into dealer for humming noise at 70-80 mph.
Doesn't matter if on throttle or off, in gear or Neutral, noise still persists between 70-80 mph.
Sounds like road noise, but tires and wheels were road force balanced and replaced, it's not the wheel bearings.
Dealer not able to pinpoint the issue due to wind noise to strong at that speed for the chassis ears. Does not duplicate the issue on hoist.
Does anyone have any ideas?