Changing alloys

[Kulli]

Hi,

I am looking to change my alloys on my 911 3.2 1989 (temporarily) from fuch to boxster 17 in alloys (look like twist alloys, also seen them called Turbo Look 1).

I ve done a bit of research - I am not a mechanic but the
exisiting alloys are Fuch alloys are 16inch, fronts have ET 25, backs have ET 11 (from a website). Tyres are 205 x 55 ZR 16 and 225 x 50 zr 16.
The boxster alloys are front- 205/50 r17 ET 55 7 inch wide, Back 255 40 r17 ET 50 8.5 inches.

So I think, their is a ET difference. What do I need to get the boxter wheels on. My thoughts are for front difference in ETs are 55- 25 = 30 - see need spacers of 30mm and for back differnces are 50- 11 = 39 so need spacers of 40mm. Have I done this right and is there anything else to consider?

Next part is, does anyone know of a store/website that sells quality spacers that are not too expensive. (Some spacers are costing more than the a new set of tyres).

Look forward to replies.

regards,

Kul