Loud howl in cab

[LTS]

2015 Silverado. When going 75 mph or more, and usually a side wind, I get a real loud howl in the cab around the driver side door. Not like a normal wind noise, like window or door seals. it gets loud enough that you can't carry on a conversation in the truck. The local dealer won't ride with me to hear the noise, and says they don't know where to start. That is a pretty bad response. Any ideas or suggestions? Can I have the name and email of the district rep for Phoenix?

[Doug_Scott]

What happens if you crack a window open? On my 2010 Ext cab Sierra, if you open the two rear windows only, and drive at 45mph, you would swear there is a helicopter hovering in the back seat. The "chop-chop" sound is very loud, but will stop the instant you crack open a front window.

 

The dealer may simply mean that since 75mph is not a legal speed to drive at (in most areas in both Canada and the USA), they will not put their employees at risk for the test drive.

[LTS]

I tried to crack the window, and can't really tell if the noise is there are not, because of all the wind noise. 75 MPH is the posted interstate speed limit in Arizona.