I have an 89 GTU with some aftermarket springs that are B&G that lower it 1-2.5 inches and I am putting PIAA 17x8 inch rims with an offset of 42 mm and a lip of 32mm. what will I need to space my rims out enough so that they will not hit my springs? And also will I need to get longer studs for the front and back?

 

if the rims are 42mm offset then they should fit fine in the rear, you may need a 3mm-6mm spacer for the front. you might want spacers in the rear to push them out closer to the fender. do a search for the official wheel fitment thread. itll tell u everything u need to know

ive got 18x8.5 35mm offset up front. and 9.5in 35mm offset in the rear on my 89 vert with no spacers. but i needed a 9mm spacer up front on my 87 TII for some reason.

 

I'd say more like 7-17mm would be needed for the front, especially with a drop you'll need lower offsets.