The first important measurement on Porsche wheels is the bolt-pattern. It's 5x130mm which means that no other wheels from any other make of cars out there will ever fit on a Porsche. So don't waste your time trying to find inexpensive wheels from a rice-car to put on your Porsche. Some of the early 4-bolt 924s can use Ford wheels, but I haven't messed around with that fitment, so no comments on that.

The following lists stock wheels that came on various model Porsche 944/951 cars.

wheel size (offset)	standard front	standard rear	optional front	optional rear
'82-85 944NA	15x7" Cookie Cutters (23.3mm)	15x7" Cookie Cutters (23.3mm w/21mm spacer)	15x7" Fuchs (23.3mm)	15x8" Fuchs (10.6mm)
'85.5-86 944NA	15x7" Phone Dials (23.3mm)	15x7" Phone Dials (23.3mm)	15x7" Fuchs (23.3mm)	15x8" Fuchs (10.6mm)
'87+ 944NA	16x7" Phone Dials (52.3mm)	16x7" Phone Dials (52.3mm)
'86 944 Turbo	16x7" Phone Dials (23.3mm)	16x8" Phone Dials (23.3mm)	16x7" Fuchs (23.3mm)	16x8" Fuchs (23.3mm)
'87-88 944 Turbo	16x7" Phone Dials (52.3mm)	16x8" Phone Dials (52.3mm)
'88-89 944 TurboS	16x7.5" Club Sport (65.0mm)	16x9" Club Sport(60.0mm)