Tires: tyre pressure, tyre air pressure, pirelli pzero

Question
Dear sir,

  i own an Octavia mk1 1.8t .when o.e. it was 160hp with 205/55r16 89 or 91V,weight 3100lbs completely empty,car placard 2.0-2.2 and 2.2-2.4 .
  Now:240hp, Bilstein PSS9,4POT GALFER,G-REDDY intercooler,new exhaust and 225/45r17 with Pirelli PZERO 94Y,i think XL.Ilive in Greece,usual temp 20-30 C. Could you advise me in tyre air pressure,empty and loaded?
        Thank you,
     TSOUMAS Nikolaos

Answer
Nikoloas,

It turns out that the load carrying characteristics vs pressure are the same for both sizes.  So the same pressure should be used.

But that doean't mean that the 2 sizes will behave the same.  This is more a function of the tire than the pressure.