Would it be bad if I got 18x7.5 rims all around? How would that affect handling/traction etc...?

 

I assume that you are going to use these rims for winter. I think that you may upset the VDC if you eliminate the stagger, however, I have read someone post that they are using the same size on all four corners on their coupe without any difficulties.

 

Here's the answer I just posted for you at freshalloy:

NYGPOT

If funds are limited, why not go to the classified section of my350z.com. Many "Z" owners are selling their new Cast 18" wheels. I've seen prices of $400 to $600 per set for unbleamished examples. That price includes tires. It's just an idea. and IMO, whould be better than after market budget 7.5" rims.

Lou