Hey guys, first post here.

I have recently started a lease for a 2008 Subaru STi. On that year, all of which came fully loaded, meaning that it comes with 4 BBS wheels with 245/40R18 Dunlop on them.
I am thinking, since I am returning the car to them anyway, why buy a set of winter rim/tire to save those BBS wheels from salt and scratches? They are not mine anyway.
My idea is to buy a set of 4 x 245/40R18 WINTER tires and put them on the stock BBS. Then I'd buy a set of summer rims that I could use in all other seasons and possibly keep them for my next car.
My idea came from the quote I got during last oil change: 1600$ + tax for a set of 4 rims/tires 235/40R17 (not including the TPMS, that would be an extra 100$ and labor). That's unreasonable for me. Besides that, I am skeptical about having an extra half inch of sidewall and 10mm less of width to improve the safety of the car.
So, any thoughts? Opinions appreciated! Thanks.