Could be a bad Hub assembly. It shouldn't be bad, may have been tire rub at full turn, but you said it does it going strait too.
Unless somethings rubbing it inside the wheel well, its a bearing.. Our cars use a sealed hub assembly, when it goes it really goes.
-You already ck the lug nuts
-Check the Caliper Bolts
-Check the pads, make sure there not worn out
-Check for clearance in the wheel well, make sure nothing rubbing
If all is good, jack up the wheel that you feel the grind on. Then grab the rim with both hands. Try to make it shift back and forth. If it does and you feel a good size pop its the sealed bearing. Spinning the wheel wont help ID it when there is no wait on the tire.
Hope this helps..
Nissan OEM 370Z Front Wheel Bearing Hub Assembly - performance parts