ok. i Just bought the Eibach pro kit springs for my z. although i have 245/40/18 tires on the front, the eibach springs are suppose to drop the car a inch in both the front and rear. will the springs work ok, or with the tires rub?

 

You will be fine. I had 245 40 19 on front lowered on sportlines and didn't rub.

 

Depends on your offset !! What offset amd width wheels are you running?