First off
Previous car a 2008 civic si 4d I got tired of it so I traded in for 2009 G37x sedan I really like the G. I'm wondering if I'm gonna have problem if I put my Bbs evo mr wheels 17x8 +38. What tire size do u guys recommend for it, right now it's sitting on 235/40. I know it's the same lug pattern but I haven't tried to put them on yet.
Here some pics:


Thank you in advance..

 

Here's a good calculator
https://www.myg37.com/forums/tire_rim_calculator.php
Your stock tires on your X should be 225/55/17
so 245/50/17 would work, a 40 series tire would be way off, like +9% difference so your VDC, ABS, and speedo would be way out of range, and no way would your AWD handle that.
Nice wheels BTW!

 

If you already have these wheels, why don't you test fit them and see for yourself how they fit and look?

As far as what size tires, just use the calculator posted in the post above and get the size that is the closest to OEM size.

 

Thanks for the good info, gonna test fit when it warm up a little.

 

Ok I test fitted my bbs rims, after I removed a nail on the tire. It fits no problem at all for the rear. I'm assuming no problem for the front but gotta test it too just to make sure. If all goes well, tire shopping next.