ROBQT, try these tyre pressures.I have to manage my tyres in the vette it's not really the car for me but it's more predictable on n over limit I have to use softs all the time
For Medium: 20 20 19 19. For soft, just one click down all around. The same goes for super softs.
Soft: 19 19 18 18.
Super Softs: 18 18 17 17. I hope it'll help you. Atleast it is working for my setup, but then you have a reference to build from