i am currently looking at a set of 18x9 z06 wheels and im wondering what sized tires do i use with those

 

I'm running 275/35/18 on all four corners.

 

^^^ what he said

 

285-35 on my Z convertible. No problem. +56mm offset.

 

+2 on the 275s

No fender rub either.

 

If you're worried about rubbing in the front you can also use 245/40/18s

I run 245/40s in the front and 275/35 in the rear

 

What's the offset on the wheels? They appear to be aftermarket wheels, since 18x9.0 was not a factory size on any year Z06. Whether the tires will rub depends in part on the offset of the wheels, and how deep they sit in the wheel wells. Properly spaced, you should have no trouble with a 275 section-width tire of the correct diameter, since 275 section-width tires were standard equipment on the 4th Gen WS6 and SS coupes.