I'd say be safe and go with the +48mm offset. It would suck to buy rims that do nothing but look nice at a stand still but give you issues while in motion.
check out PRO_5's car. I'm pretty sure his formula is:
Slammed + Sounds + 18x7.5 +48mm offset = No Rubbing
I know your suspension is stock, but it's better safe than sorry. (thumb)