What does the car weigh?
Y'might call Hoosier Tire. They work well and aren't super sensitive to tire pressure. I'm guessing that your original 15X33 config is in the ballpark, but they can get you the right tire size, and right sidewall . . Which, on lighter cars, makes a big difference. Has a lot to do with how the wall wrinkles and keeps all the profile on the ground . .