OKI-FD

Ive searched and searched, went through hundreds of pictures and I still figure this out or get a straight answer. Im looking to get agressive with my setup, however im on stock body. I was gonna go with 18x8.5 18x9.5 +20 all around with 225/40 235/40. The pic below is those specs. Now it looks like it fits there but some threads and pictures show a +38 barely fitting, others have +22 and even +20 fitting in the front on stock body w/ a roll of course, but they should fit with the proper alignment yes? I dont plan on SLAMMING the car either but it will be lowered on HKS hypermax III suspension.

*SIDE NOTE* Ive seen 18x10 +38 fit....im not sure if this is right but say +38 down to +20, 18mm difference or .7 inches so a 18x8.5 +20 should sit near a 18x10 +38 right?
Thanks in advance. I think ive just confused myself.