[BMW_NP]

Hi
basicly i manged to punture my RFT twice now i got it repaired the first time and i had a punture on the same tyre i got repaird a few months ago,

And i was thinking of getting a new set of rims for my car just was waiting for the tyres to wear out (2-3months) but i though might as well get new rims now, what i wanted to ask i check the current tyres on my car and both front and back are 225/45/R17 i have a 325i , but reading a lot of other threads and looking in the bmw accessories book the set up should be 225/45/R17 front and 255/40/R17 on the back, could it be that the prevois owner changed them , because from what i can see the alloys the OEM

and if i was to upgrade to lets say 18's what tyre size would i need?

thanks