with the 2nd gen frontiers you can't go smaller then a 16 inch wheel because of the disk brake size. If you want to go wider you can swap the titan control arms and push the front out 1.5" per side. Also you gain some wheel travel.
i like this idea. next set of tires is gonna be that size.I Will Be Running Bfg/km2's 305/70/16 On The Factory Nismo Wheel 16x7 And Ive Already Test Fit Them And Drove Without Issue. It Is The Same Diam As The Bfg/at 285/75/16 I Had On There, Only .9" Wider