QUOTE(Downerman @ Mar 25 2014, 07:09 PM)

Great info... BTW I took off one of the 928 wheels... inside says 7J so it's a 7" but I do get this.... the offset has everything to do with this. Had a line on some 7 X 16's off a 911 but now I'm thinking otherwise. Anyone else??
Dave
I think the info being presented from both sides is not directly to the point.
First, you say 928 wheel. There were a lot of different wheels, some look
the same but are not. You have to go by the part number or info stamped
on the back.
What you really need to know will be stamped on the back of a wheel. For
example, you said "7J" so it is a 7" wheel. Also check the front, it could
be 6". After the 7J it will have "ET" followed by a number. That is the
offset in mm.
Offset is key. Higher offset (more positive) means the wheel
will sit deeper in the opening. So, if you have a larger offset than you can
fit, it is possible to add a spacer. If you have to low an offset, you are
screwed.
Also, if you have, for example, a 6" wheel with 36mm offset, then a 7"
wheel with a 36mm offset would stick out 1/2" further on both sides.
But if it is a 7" with 23mm offset, then the back side would line up and
the outside would be 1" further out.
All cars are slightly different, but in my view the optimum offset to get
the widest tire or wheel to fit the rear is 35mm. Depending on the
tire and/or camber and springs, you could vary from this. It pays to
check your own car yourself. The front is almost never an issue, but
you have to avoid too much offset on wide wheels to keep from hitting
the shock dust cover.
I once put the 6" 52mm offset phone dials on the car with 205/60 tires
(I had a 924S), they rubbed on the inside rear.
Good luck