Wheels...

[20vWill]

I like 14's (or 15's max) on the AE86.

Something like 14x8 in 0 to -10mm offset would fill the arches nicely without going too wide. A 185/60 tyre will stretch nicely over an 8" rim to give a stiffer sidewall and more direct, sharper feel.

I don't know much about big rims, since I have no interest in them, but if you want to run a lower ride height, they are a no-no.

Doing some simple mods to the inner arch seam lip and the bumper-to-fender tab will give a little more clearance, as will adding neg camber and binning the rust promoting plastic wheel arch trims...