lsirg22

Im trying to get new 16x8 wheels for 1989 Firebird. I sourced a set from Classic Industries. They recommend offset of 0mm for front wheels and 16mm for rear wheels. Is this the correct setup for me?

Abubaca

iTrader: (3)

Welcome to TGO.
Yes. That's what came factory. 0mm up front. +16mm out back.

....now that being said, a lot of guys will run a square (matching) set up of (4) FRONT wheels, with 0mm offset on all four corners. This will allow you to rotate tires/wheels on all four corners. The rear (with front wheels) will now also be pushed out 16mm, which is a look some people prefer. Most aftermarket wheels made for our cars come this way with (4) matching 0mm offset wheels. Very common. Still, if you're looking at a set of new original 16x8 wheels, I'd just stick with stock offset. 0mm in front. 16mm in back, as Classic Industries recommends.

lsirg22

Thank you for your expert advice Abubaca. These are the GTA style wheels I have chose to purchase. I like the style, they are in stock, ship free and the price is affordable. I have a set of NOS black center caps and medallions. I acquired these years ago before PMD dissolved. They were constantly getting stolen off the car here in Chicago. I'm hoping they'll fit the wheels. Coincidently they sell center caps that are described as for 0mm offset wheel setup. Should this concern me? Additionally I was curious what purpose positive offset of a little over half inch in the rear wheels serves? Is it so you could add a larger wheel in back, saves wear and tear on bearings etc, or just looks cooler? Sorry if these are rookie questions lol. Thanks for your help.

Abubaca

iTrader: (3)

Why? Oh jeez, there are all kinds of myths and legends out there as to why! Everything from extra stock, to keeping the track from getting TOO wide for handling dynamics, to mis-ordering, to crazy space aliens. But if ya think about this....the stock 15" wheels were 7". The 16" when added in 85 were 8". So with a zero offset like the 7" wheel, it would put half the extra inch on the outside, half the extra inch on the inside. The +16mm puts the whole extra inch on the inside, and I have to believe the was done on purpose for that reason. Why.....I have no idea. No reason I've heard makes anymore sense to me than any other. -and the EASY obvious choice was to leave it at 0mm. Sooooo, had to be a reason.

As for the caps fitting 0mm wheels... The offset wouldn't affect the hub/center cap relationship, at least theoretically. Now that doesn't mean that those specific wheels don't have some slight casting difference to where the different wheels might fit the center caps differently. On that matter I just don't know.
EDIT....So to my knowledge, when aftermarket wheel companies change the offset, it's basically the outer rim (star wars) that moves. The hum/spokes aren't any different. It's just how the two are assembled in relation to each other. But how GM had 'em made on a mass scale? -Perhaps the inside of the hub is actually machined down 16mm, effectively moving the whole wheel (rim and hub together) in by 16mm. That would potentially affect how the center fit. Just a thought. Not sure.

lsirg22

Very interesting. I believe i get it after rereading your comparison of 7" vs 8" wheels. Perhaps when they introduced 16 wheels in 85 the engineers figured it was best to tuck it in where the 15" wheels resided in relation to the axle as it was originally designed?? Like you say there's gotta be a reason.
I certainly hope my center caps fit properly. I would like to put them to use.
I would gladly donate the old factory wheels to a 3rd gener in the area. They'll need refinish and paint but for someone on a budget looking for factory original wheels it could be the answer. Is there a way to donate parts on this forum?
Thanks again

Abubaca

iTrader: (3)

Just post them up in the classified section. Just put something like, "FREE local pickup only" or something like that in the title. ...You could also try the regional forums. I don't think you're really supposed to post for sale/wanted posts anywhere but the classifieds, but I do see 'em on the regional boards from time to time.

Also, where are you from? ...you can put it in your info section under your name. Go to the top left of the page....in the blue bar....click USER CP. -if ya want.

lsirg22

I just subscribed to the NW Indiana/Chicago regional forum. I'll post these free wheels as well as any number of other interior parts I have because I recently restored the interior from headliner to carpet and there is some aged but still usable/restorable original parts in my garage. Thanks Abubaca.

Abubaca

iTrader: (3)

You're welcome!

TTOP350

iTrader: (8)

Stick with 4 front wheels, you'll be much happier.

kentuckyKITT

iTrader: (4)

What he said! I have two cars with the correct offset and it's like pulling teeth to explain to the tire shop that the tires move, NOT the wheels. Rotations are expensive too since you have to dismount/mount balance all 4 tires. You'll need crayons and finger paintings to get it through their heads of how to rotate these tires and whatever you do, don't bring the 4 wheels/tires in loose and try to mark them and explain moving the tires, because that goes over their head too! They're like "well if you took all 4 wheels off, why did you bring them in, you just need to move them yourself." ARRRRGGGH!!! Best to avoid it altogether and just get 4 front wheels. One of these days I will on both cars. It's always a headache when I try to get my tires rotated.

lsirg22

Thanks KITT. It makes good sense what u say about the headaches involved with tire rotation. I'm leaning towards the zero offset setup.