Wheel Bore question
 

So I'm looking at picking up some wheels, and I've been trying to dig through these threads but their like encyclopedias.

I'm wanting to run:

Front 17x7.5, Rear 17x8

my question is there's two options with the bore:

56.1mm and 73.1mm bore. What is this referring to? And which should I go with?

Thanks

You need 73.1mm. 56.1mm won't fit over the hubs, front or rear.

Thank you very much.

Last question, should I be running the mixed combo, or straight one size? thanks