whats the narrowest and widest tire i can fit on to a 17x9 rim, the wheels are on a fc, i have at the moment 255/40/17 at the back, need to get some for the front. will 225s fit? or is the rim too wide for it?

225's will fit ok but suck in, a 235-255 will fit best, if you use Nitto tires there sizes are misleading and you can fit a 275 Nitto NT555R on a 9J perfict fit (it's the same width as a 255) and you can even fit the 315 Nitto, but it will bow out a little.

Have you already had these wheels up front? 9's generally are too wide to fit without fender flares and/or extreme camber and/or wider fenders.

255 will definitly fit the rims..... but make sure on how it fits on yoru car, and giving the offset would help other members give you a better answer

the fronts aren't fitted yet, i need some tires on the wheels first, i was thinking fitting the narrowest tire, 225s i think i will get now, the offset are +42 front and back, with 5 mm spacer at the back, still need to find out how thick spacer i need to make the front fit.

I'm guessing a 25mm spacer will net you a +17 offset for the front. This will work if you stay with something like 225's up front and have fenders such as the ones from BN Sports or the Corksports version of that same fender. They'll let you run that wide of a wheel.