18x12 rear wheels

[RedRiderZR1]

I have a set of wheels I was going to put on my other vette, but decided I want to put them on the Z. They stick out on the C5 and I'm not interested in fender flares. Question I have is will these work on the Z. They are 18x12 wheels with 335x30x18 tires mounted. The backspacing on them is 8 inches. How deep can you go with the rear wheels without rubbing? I know the stock rears are 7.37 inch backspacing. Is there .6 inches of area back there still to fit these without rubbing?

I have done a search and seen that there are people running 18 and 19 inch wheels with 335 and 345 width rears, but not sure of their backspacing and if they had to do something to the car to fit them.

Anyone out there running 335 and 345 tires and can confirm they fit under there and what their backspacing is and/or mods to make them fit without rubbing something.

Thanks.
Greg