Roof Bars and lots of noise

[Yorkshire Devil]

Although it's not a surf it is a Toyota Land cruiser Kzj70 swb I fitted some roof rack bars on the top and couldn't believe how noise and vibration travelled through the car. Is this normal? I didn't think two bars sat on the gutter rails would cause so much humming and groaning.

[KERRSURF]

I didn't get any vibrarion but my bars did create a bit of noise.

[shokenore]

Rubber pads on the fixing feet?
Do the bar ends have end caps or are they open?

[tweak'e]

used to get it a lot with roof racks on vans. need to sit them in the right position. its just the way the airflow comes over the vehicle.
i had my big ladder on the back of the work ute the other day. at 80km/h it started screaming. one very loud trip.