[cajundaddy]

19" and 20" wheels are all about the look with zero performance advantage. 18" are the choice for all GT3 Cup and GT4 Clubsport race cars and tire availability is a lot better with 18s. That said, if you like your 20" you can keep your 20".

https://www.yokohamatire.com/motorsports/racing-series/porsche-gt3-cup-challenge

https://www.porsche.com/internation...ngcars/cayman-gt4-clubsport/featuresandspecs/