There are various threads on this if you search with varying pressures being used depending on the size of tyre that you have fitted.
I have a roadster with 18" tyres fitted and have 30psi front and 34psi rear, I did try previously 28psi front and 32psi rear but didn't feel quite right though
I've got an si with 18inch wheels & use 34front 38rear-I've gone up on pressure as it felt "squidgy" (technical term) on the standard run flat pressures.
Regards
There are numerous threads, on numerous forums, on the right tyre pressures to use, and at the end of the day, provided you stick within the legal limits, it's down to personal preference.