Well since its a ka I would go with 18x9+10 Front and Rear on a 225/40/18 tire but the ka will still have problems spinning those int he rear....My favorite for an S14 has always been getting Z32 Rear Turbo wheels 16x8.5 in the rear and stretching them in the rear with 205/55/16 tires the ka can spin those with ease depending on the tire.
If i had an S14 and had no MOney which is every day lol. i would buy a set of Z32 Twin Turbo wheels 16x8.5 front and rear get some spacers to line them up witht he fender. and slap some 225/50/16 wheels on all 4 corners they look really nice slightly stretched, i would also polish the wheels, it looks really nice. also another thing you can do is go witht he R333 or R34 GTR wheels there 17x9 though. Damn i wish i was 5 lug.