I just responded to another thread on this same issue.
My 235/40/18 Nittos were really close to the front A-Arm nut - on stock SRT Rims. I ended up putting spacers - 10mm just to be sure I didn't have a problem. I also put 12mm spacers on the rear just to keep the look balanced. Turned out really nice.

I don't know why I seem to be the only one with clearance issues on the front with this size tire? The car is NOT lowered although it does appear that the front springs have settled a bit.

Oh yea, i also went with 275/35/19 on the rear.

Cheers,
KrzyFast