Just get a 4 wheel alignment done using the oem settings for the 18" wheels.
Use this as a starting point and tweak from there to suit what you are trying to achieve.
If your car is not lowered there should be ample adjustment for toe and camber on the rear.
Plenty toe adjustment on the front
Zero camber adjustment on the front with stock upper arms, so you will require adjustable front upper arms if the camber is outwith the manufacturer's specification.
Edit: what Dan has just said. ^^^