I'm thinking of getting the 5Zigen Hyper 5ZR that only available in 18x7.5, highest offset is +48. Would there be a fitment problem as I'm lowered around 2inch with Bilstein PSS. Also what tire size do people recommend, 225/40/18 front and 245/35/18 rear are closet to stock wheel ratio?

 

If you have 7.5" all the way around, the widest you can go in the rear is 225. Those wheels will rub if you don't roll your fenders btw.

 

also, remember that those wheels are much heavier than your stock wheels!

 

so will 245/35/18 tires rub in the rear? What would the effects be if running 225/40/18 tires on all four corners?

 

245's won't fit on the rim. You will have a little more oversteer when running same width tires front and rear. You won't really notice the effects until you start pushing the car pretty hard.