Will these wheels fit?
 

Front: 18x8 45 mm offset 225/40/18
Rear: 18x10.5 45 mm offset 285/30/18

Car is a 2000 Boxster S, stock height

With 10" rear I'll say yes flash with the fenders
With 10.5" it might be just little too wide

I have 10" rears and they just fit. I would not want to go 10.5". Yes, it's that close to the shock tower. My offset is 45mm(rim is ET65 and I have a 20mm spacer). The fronts should be fine.

that's a bummer... I thought i found a good set of wheels. OK, thanks for the replies guys!

Factory rims are like 7.5"in. In the front , 9.5"in. In the rear. With factory recommended tires, actual tire contact on pavement is 8"in. In the front and 10"in. In the rear. It works perfect for me since I don't have twin turbo's .lol. A simple factory spec'd 3.2 litre.) I have enough grip action to keep me satisfied.

Rears wil fit just fine. You will need spacers though. I was running 10.5 rears ET32 with no problem on a lowered Boxster. Tires must be 265.