Looks like I might get my hands on some IS-F wheels!!
They are 19x8 and 19x9... What size tires will be perfect for 3GS?

Btw, I checked specs on IS-F... and it comes 225/40 for front and 255/35 rear??
I thought that was kinda odd sizes...

 

if the wheels do come with the tires you stated (225/40 & 255/35), you'll be fine im sure. the factory 3GS 18" wheels are 18x8 and running 245/40/18's. the tire calculator says 225/40 & 255/35 are the exact tire size diameter as your stocks. you should be fine. im sure the 9" rear wheel will make minimal difference in fit. the offsets of factory wheels are very conservative anyway!

post pics if you get em.

 

Thanks! That's what kinda confused me... We have 245/40 tires on ours so I was expecting something like... 245/35 in front and 265/30 in the rear...

I'm trying to find time to go look at it. May be have it test fitted to check the off-set...

 

The stock IS-F rims don't clear the factory brake setup of the IS350. The GS350/430/450h/460 has the same front calipers as the IS350. The rears are very similar. If anything, you will need to use a spacer for the wheels, otherwise you wont be able to get them on.