I'm getting a 2010 SS with 20" midnight silver wheels.

Will I be able to fit a set of 18" C5 vette wheels on to the rear of the car?

My 4th gen uses 18" vette wheels with drag radials, and I want to know if I can swap them onto my 5th gen for drag strip outings.

 

You may not be able to clear the brake calipers.

 

Front brakes are 14", rear are 14.4". You'll want to make sure you have enough clearance to fit the rims on, just like Jason noted.

 

don't forget that the overall diameter of the tire is a good bit larger for the 5th gen too. The 20" rim on the fifth gen has as high of a sidewall on the tire as an 18" rim on a 3rd or 4th gen would.