wheel spacer confusion, 17" 993 wheels Options

[retrotech]

I just got my 17 x 7" 993 wheels. I was told they are a 55 mm back spacing, and I would need 20mm to make them fit
When I measure from the back side its 5 7/8 to rim edge.
I measure my 15" deep six wheel its 4 7/8 to rim edge.
20mm is about 1/2" right? It would appear I need 1" spacer.
Am I missing something? Once again, what size spacer have others used for this aplication?

thanks for your help.

[smrz914]

Be carful that you are measuring the clearence on the back of the wheel. Meaning the space between the tire and the "trunk wall" The outer fender can be rolled a little if need be.

The 993 wheels look funny b/c you only have one on the car. the fuchs are not a compliment to the 993's.

Just out of curiosity why do you say 2.25/50 not 225/50? I have 225's on my 7 inch rims but the tires have rim guards that add that width.

Look at my site (link below my name) for some picks if you need to decide on the look.