I've narrowed my choices down to these rims and the Black ZR1s. I already know I will need spacers but I was wondering if these 18x9.5 rims will fit my car.

Here are ones I've found on ebaymotors.
http://cgi.ebay.com/ebaymotors/_Car-...=p4506.c0.m245

56mm offset (If I read correctly)

Seems good for $500, but will the 18 inch rim do anything over a 17 inch rim? (Make my car slower, handles worse, etc.)

It's these rims versus the black ZR1 rims 17x9.5, the ZR1s are a little cheaper but if these C6 fit I might go with them.

Thanks.