i was told 4th gen wheels wont fit a 3rd gen but ive seen a 4th gen bird that has 3rd gen wheels iroc wheels on it and seen a 3rd gen on here with 4th gen wheels on it so obviously its possible but how?

The secret is..........
























Wheel spacers!!

The 4th gen wheels fit on the rear just fine - it's the fronts that have a problem - the backspacing is off and you have to put in wheel spacers in the front to get the wheels out of the wells and keep from rubbing on the suspension components.

4th gen wheels won't fit on the rear of these cars, just like they won't fit on the front; they hit the inside of the wheel wells.

The 4th gen rear is about 1-5/8" longer on each side. Given the difference in the width of the wheels and all that, 1¾" spacers are what people commonly use on both front and rear.

I forgot, I have a 4th gen rear!

You're right - 4th gen wheels need sapcers all around!

With a 4th gen rear, you won't need spacers in the rear.

My friend got ZR1 rims on his 4th gen. I plan on buying his rear end in a few months [3.42 gears from his 2001 trans am]
Should I just buy his old rims too and put some slicks on them to use at the track or when I wanna go fast?

Kinda bringing this back but does anyone know what size spacers I would need for the front wheels?

2" to 2.25" I ran both sizes on my cars.
I have 2" spacers on the front right now.

I had to use 2 1/4" spacer to get my ZR1s on the front. It depends on the backspacing of the wheels you have, not what I have or somebody else has. Once you have your wheels, measure the backspacing, the difference between that and your factory wheel backspacing, will be the size spacer you need.

www.skulte.com is a great place. The guy is a member here, he is super helpful.