275/60 on a Demon?

Hi guys! I already searched and just can't get the answer I need.

Want to run 275/60R15 MT Street Radials on the back of my 71 Demon. I have 255's on there now(TA Radials), and it really looks like I have room for 1 inch taller and wider BUT just wanted to know if anyone else is running them.

I have 8 inch wheels with 4 1/2 backspacing and my car sits low. The TA's just cant handle 550 ftlbs of torque on the street and they are terrible on the track.

I hate that look of tires hanging out past the fenderwell and I surely ain't jackin' up the back end. Any real info would be greatly appreciated and pics would be great! Thanks!