C6 Z06 cars use rear 19x12" wide wheels with a +59 offset using a 325/30/19 tire.
A 19x10" +59 wheel will be far too recessed into the widebody rear 1/4 panels:
[URL unfurl="true"]https://www.willtheyfit.com/index.php?width=325&aspect=30&diameter=19&wheelwidth=12&offset=59&width2=285&aspect2=35&wheel_size=19&wheel_width=10&offset2=59[/URL]
You need a +34 offset 19x10" wheel for the face of the wheel to be where a stock Z06 wheel will sit:
[URL unfurl="true"]https://www.willtheyfit.com/index.php?width=325&aspect=30&diameter=19&wheelwidth=12&offset=59&width2=285&aspect2=35&wheel_size=19&wheel_width=10&offset2=34[/URL]
My advice, use 2 Z06 19x12" +59 wheels and it will look proper without spacers and all that crap.
BTW, I take it your front wheel is 18x8.5" instead of 18x18.5"?
[URL unfurl="true"]https://www.willtheyfit.com/index.php?width=325&aspect=30&diameter=19&wheelwidth=12&offset=59&width2=245&aspect2=40&wheel_size=18&wheel_width=18.5&offset2=56[/URL]
That's one hell of a tire stretch.....................you win the world record!!!! LOL