Originally Posted by Joe@ApexRaceParts
You could very easily use our most concave profile 3 wheel in the rear of your car. Either an 18x9.5" ET22 with a 265/35/18 tire or an 18x10" ET25 with a 275/35/18 tire could be used as a direct fitment.
For the front I would recommend our 18x8.5" ET35 wheel with a 235/40/18 tire. This is indeed a profile 1 wheel but in person they do have some concavity compared to pictures on the internet. Unfortunately it is very hard to fit a concave wheel on the front of a Z4M without camber plates. To give a comparison our 18x9" ET31 wheel is narrower than the normal 18x9.5" ET35 front wheel set up that most track guys will run but, the 18x9" ET31 will sit at almost the same point relative to the fender as the 18x9.5" ET35 so camber plates are also necessary for that wheel even with a narrower tire.
OK, coming back to this question. What if I wanted to go with 19" wheels? What size recommendations would you make, if any?