kanut, you run 275/60/15’s on your GN right? do you get any rub on the frame or on the outter lip of the wheel well? what backspacing do you need to run those? Anyother G-body guys run that size as well? It seems like its hit or miss with that combo on a g-body. My pops was gonna put some BFG’s on the GS instead of the radial Gt’s so now i have (2) 275/60/15’s and (2) 255/60/15’s to use on something. Obviously the 255’s are too big for the fronts on a g-body becasue even my 235’s rub but if i can’t use the 275’s for the rear i’ll use the 255’s. the 255 are brand new and the 275’s only have about 1000 miles and one good burnout on them.
255 will do good on the back.
i use 275/50/15s drag radials but have 4.5" back spacing and a custom 10inch rim.
gnx suspension helps but i think the biggest disadvantage on a gbody buick is the wheel well lip moulding because it sticks in further . im not sure you have that thou
275’s will fit on 8 inch rims but will budlge a lil on 3.75 backspacing those are the rims will has !! my old ones 
dam i miss those TT II;s
btw thanks for calling me back man !!! wtf
they will almost certainly rub the frame
i had 255/60/15 on my regal and had plenty of room with a 7’’ rim
the 245’s were more than fine and i was told they would be ok w/ that backspacing :dunno:
I run 275/60/15 nittos all the time on my GN, if you seen my car, u seen how it looks with them. You need atleast 3.5 inches of back spacing i believe, and 8 inch wide rim, thats what mine are. I did have some rubbing problems around turns, but i got a set of airbags in the rear springs and no more rub… hope this helps… an upgraded rear sway bar would help with the rub also.
we are talking 275s mike
22psi is right unless 8 inch rim=rub
my bad mike. it all gravy.