wheel offset

[Godfrey DiGiorgi <ramarren@domain.elided>]

I know this question went around recently but I can't seem to find it. I'm
looking for the stock wheel offset used on the type 105/115 Spider. 

Another thing that's unclear to me is the definition of offset as positive
or negative. I understand that offset is measured from the centerline of
the rim, but does "positive" offset increase the track (move the tires
outwards with respect to the car centerline) or decrease it?

I've read conflicting definitions so I'm trying to find out if there's a
definitive answer to this.

thanks,
Godfrey

------------------------------