Old thread revival! I'm getting this too, low speed rumble strip noise feeling when slightly turning. 2WD Limited 4Runner. Sounds and feels like the tires rubbing but I cannot find any evidence of this actually happening.
I no longer have the 4runner but changing the front and rear diff fluid and the transfer case fluid didn't change the sound I heard. Since my posts I've spoken to other 4runner owners and some have heard it. In my opinion I think it's a characteristic of the vehicle. Some are in tune enough with the vehicle to hear it. I never had any issues with the driveline.