go search offset calculator on google.
the stock s13 wheels are (i think) 6inch wide at +40. I assume you're 4 lug,
and the only 4 lug fn01rcs made are 17x7+35, 17x8+35, 17x9+20, I think, haven'tlooked at them in awhile. it's possible to run 17x9s with a +20ish offset, with 245 tires if you roll yur fenders AND run at a reasonable height.
don't go less than 7.5in wide imo, 7.5 inch wide with 225s or 8inch wide with 225s or 235s with offsets in the +20 to +30 range should fill the gap but not extend beyond the fenders. might want to take a look at other wheels, don't limit yourself to just the fns.