So I've had my 4runner for a few weeks now, no issues. Drove about 150 miles yesterday with nothing weird, then we go to get dinner last night and it sounds like metal grinding metal, but it's rotational kind of like "whomp....whomp....whomp", but I cannot tell if it's up front or in the middle or in the back while in the vehicle.

I tried having the girlfriend drive by me a few times as well as a short safe ride standing on the step and holding onto the roof rack and I cannot hear it outside the vehicle. It adjusts with speed, breaking does not seem to effect it (besides slowing it down), it seems to quiet down a little when turning left but doesn't go away and comes right back once going straight.

I've visually checked everything I can think of, I don't see any signs of anything rubbing anywhere. It's a noise I've never personally experienced and I'm about 90 miles from home where all my tools and my "mechanic" buddies are. I tried recording a video and the sound did not come through.

Any ideas?