245/40/18 on 18x9.5?
 

The BFGoodrich Rivals (does not have 255) for this size is 198/tire which fits my budget. I was looking at Z2's (comes in recommended 255/35 size) but personal issues came up so I wouldn't be able to afford them anytime soon. I have already ordered the wheels so I can't do much about it at this point.

I know this is a mild stretch but I was curious to see if anyone has done this. If you could provide results or recommendations that would be much appreciated.

Those are over an inch taller than the stock tires. A 255/35 or 245/35 would be better. Hankook's Ventus R-S3 v1 comes in 255/35 and is only a few dollars more than the BFGs. Or Kumho Ecsta XS in 245/35.

If you're willing to bump down to max performance instead of extreme performance, there are a bunch of decent tires under $200 each.