Jimm 2/2/2013Several possibilities; faulty tire tread or separated belt / bubble in the tread, faulty / worn suspension bushing, faulty / worn wheel bearing, faulty / worn shock or strut mount.
Bill 2/2/2013Maybe you shouldn't be driving this vehicle for safety reasons. I might add a loose rack and pinion could be the culprit and if comes loose guess what. CRASH
HouseCallAuto 2/2/2013The rear control arms (there are 4 of them, 2 uppers and 2 lowers) need to be replaced. probability here is near 100%. Dorman makes them at half the cost of the Genuine Nissan parts. Not that bad to replace.