Anyone know what the max offset for the rear is if i was to do only a roll for the rear qts and run 17x9 or even 18x9?

 

A lot depends on the individual tires and the size of the tire. The alignment also plays into the equation. I have seen some cars run 17X9 ET 45 with a 245/40R17 and not have to do anything. I have also seen 17X8.5 ET55 rub with 255/40R17 tires. There is a stickie on the site on sizes and offsets.
If I can help let me know.