help selecting C7 Stingray wheels
 

I just purchased a 2017 Corvette C7. I am looking to purchase black wheels and tires and want to make sure I purchase the right size? Am I correct that the front tires should be 18's and the rear should be 19's? I also have the set of chrome Stingray wheels that came with the car that I want to sell but would like help in knowing what they are worth. Any input?