Here are some basic wheel tyre combinations that can fit, if you have any more post them below.
PCD = 114.3mm Offset = 50mm
Standard Rim f/r = 17"x7"
Standard Tyre f/r = 215/45-17
(A -40mm drop is possible with this combination)
18" upgrade f/r =18"x7 1/2"
18" upgrade f/r =225/40/18
18" upgrade f/r =18"x8"
18" upgrade f/r =225/40/18
18" upgrade r =18"x8.5"
18" upgrade r =255/35-18
(A -30mm drop is possible with these combinations, however minor arch rolling is needed with the 255/35 combination)
19" upgrade f/r =19"x8"
19" upgrade f/r = 235/35-19
(A -25mm drop is possible with these combinations)
With 19's don't run any rim bigger than 8" on the front as it will hit the strut.19's will rub on the front inner arch at full lock, but this can be solved by cutting or bending away some of the plastic trim.
Of course for the nutter out there even a -60mm drop is possible with 19's.....................you know who you are!!!!:P