I have a 2017 C4S Coupe with 245/35ZR20 (front) and 305/30ZR20 (rear) on the vehicle right now. I am not sure the exact rim size, but they are OEM rims. From what I can find online it looks like it could be (based on wheel size.com):
8.5jx20ET49 and 11.5jx20ET56
or
9jx20ET51 and 12jx20ET63

I found a set of used winters that I would like to purchase, but I am not sure if they will fit correctly. They are:
8.5jx19H2 ET56 (front) and 11jx19H2 ET48 with 235/40R19 (front) and 295/35R19 (rear).

Will these work on my car? Any guidance would be greatly appreciated. I'm new to the site, but not to Porsche. This wheel and tire thing isn't my strong suit.

Thanks! Mike

 

Hi Mike--Here's a clever calculator you can use to determine how a wheel with different offset and width will fit as compared to your stock setup: Wheel Offset Calculator . As long as you're within +/- 10mm with "inner clearance" and "outer postion" for your winter tire/wheel setup, as compared to stock wheels, you'll be fine. Hope this helps!

-Dan

 

Thank you! This is much easier than the one I was using!