Jeremy Pinsly

Will these wheels fit on a stock 1990 C2 Cabriolet (no suspension changes)

Genuine Porsche Technology 18" Wheels and Tires. Wheel sizes are 7.5 x 18 front (225/40-ZR18), and 10 x 18 rear (265/35-ZR18)

Will I need offsets? If so, how much?

Porsche part numbers are:
996-362-134-55 for the fronts
996-362-140-50 for the rears

Thanks,
Jeremy

adsc4s

Around 50-52mm for the front and based on my prior experience, 47mm for the rears. I am guessing the rears will have OEM 993 offsets which is 62mm for the NB. You will need to run 15mm spacers to clear the oil line.

chame01

you will definitely need spacers to fit the larger/wider wheels. I have the same set up on my '91 C2 for the street with 1 inch adapters. The extra width is only to accomplish a beefier look. You should be ok with 15 mm spacers.