AE111 offset?? expain how it works

[Shinda]

i'm wondering how the offset works for a 4 stud car.

I have an ae111 and have been looking for 17"s for it

I've been told it's 40p offset

what does this mean?

can i get a 38p offset rim or does it have to be bigger that 40 or exactly?

[bad20v]

http://www.yokohamatire.com/utcustom.asp

Scroll down to the bottom.