So, stupidly I bought two sets of GTA wheels from Year One, and just found out they are all rear wheels, 16x8 w/ 16mm offset. Can I use rears on the front with a spacer?

I believe there is a 16mm difference in offset between them. You should be able to use a spacer, but it's going to be a decent sized spacer. What are you using for brakes? The GTA wheels have limited brake clearance and using rears on the front may cause it to be even tighter up there.

Do they have front wheels and can you exchange them? If not, get with Andris Skulte at Skulte Performance or Alan Blaine here, both of them make very nice spacers.

The offset does not influence the requirement for the wheels to fit over LS1 brakes on a 4th gen. Up until this year, I had 2 sets of GTA wheels for mt CMC car and the 4 rears became my "wets" and 4 fronts became my "dries". I used the same lil front spacer regardless of which set of wheels were on the car.

I honest don't remember the depth of the spacer that I have but it's just a little piece of round aluminum with holes to allow the studs to run through. 3/16" maybe? There is probably thread here documenting when I went to these wheels - try a search.

SCEditor is running a 3rd gen if his plans are still the same from NASA Forums.

You can run 3rd gen rear offset wheels on the front with a spacer, you just have to clear the tie rod end, that's the common clearance issue. Fronts have 4.5" backspace, rears have ~5.125". If you press ARP studs into the front brakes, you can run Mr. Gasket 7/16" wheels spacers and you'll almost get back to stock front offset. Most people say those spacers look like crap, but they work. I've run them on my car for over a year with no problems. Just make sure you have good studs.

Thanks for the help guys. Much appreciated!

I ordered a set of all fronts from them when I started running #37 '84 Trans-Am. Can you not exchange them?