I took the 92 RS in to one of the local shops yesterday for an alignment because I just rebuilt the front end and put in new shocks, struts and springs.

It looked to me like the outer drivers-side tierod is in contact with the wheel. I have 16" centerlines on my car and the service rep is trying to tell me that our cars have wheels that are different sizes and each one have to go where it's made to go.

In other words, the front drivers side wheel will only fit on the front drivers side and so on. This is the second thirdgen that I've owned and I've NEVER heard of this before. How do you rotate the tires??? They're also saying that I may need a spacer if they can't figure out what wheels go where.

Anyway, my B.S. alarm has been going off all day.

I just wanted to get a few opinions and comments.

Thanks

 

They are correct in saying that the wheels on your car cannot be rotated like a regular car. This is something that GM came up with in about 1988 or 1989, my 89 IrocZ has wheels like that and so did my 92 anniverary RS. To rotate your tires (RPITA that it is) requires the tires to be broke down and then re-seated on another rim. Sad but true.. Also, they should be able to figure what wheel goes where because they have location markings on the inner side of the rim.

 

irocs had the dedicated wheels, not sure about any other f bodys.

 

only 16s

 

'Front' & 'Rear' is cast into the back of my factory black diamond spoke 92 TA wheels.

 

Same as the above with my 85 IROC.

JamesC

 

the 16x8 wheels (IROC, GTA) are specific to the front and rear. Not side to side. If you have unidirectional tires on your rims then you cannot swap side to side unless you remount the tires you want to swap.

 

 

the later 16" rims like my car below has Rear cast into the rear wheels and front cast into the front.

 

Same here. There is also a noticable difference in the width of the lip on my front and rear wheels.

 

what about 4th gen wheels? i have a set of ZR-1's with the correct 2" spacers all around.. and it looks like my front driver side, and rear passenger side... stick out about 1" farther than the other tires. i never really looked at the wheels when i put them on because i didnt think they had this..

anyone know?

 

That's the key to the question right there. If the backspaceing of the wheels is the same, then there is no difference. The corner specific wheels only pertain to factory

 

As I understand it you have aftermarket rims. You should know what is on your car! Some of the high end late 16" factory rims were specifically made for front or rear. This does not apply on the aftermarket. The diffrence was in the offset of the rims. The rear offset was adjusted slightly outboard on the rears of the end specific rims. I read somewhere that this was to accomodate the aluminum rear brake drums which were thicker than the steel drums.

Unless there is a difference in the offset on your aftermarket rims (I doubt it!) then there is no reason that any rim couldn't fit on any hub... (not accounting for unidirectional tires).

The easy way to do this is with a ruler and a straight edge. You need a straight edge that will span the distance across your rim across the hub lip to lip. With that straight edge placed across the rim you can take a ruler and measure the distance from the inside of the hub to the backside of the rim. Compare this measurement and you can determine if there is a diffrence in backspacing.

 

Stock 16" wheels (that are cast with front and rear) are 16x8 front with 4.5" backspacing and +0mm offset, and the rears are 16x8 with 4.5" backspacing and +16mm offset. If your tires are not unidirectional (aka they have an arrow on the tire indicating they are supposed to rotate one way only), then it is true that with the stock setup, the left front wheel/tire should only go on the left front, etc etc. But since you have aftermarket wheels, what you need to do is find the specs of your wheels. Its possible that you might need a set of extremely small spacers on the front (or rear .. or both) to make the fitment perfect. Then depending on your tires, you might be able to rotate them ...

 

[QUOTE]Originally posted by Speedgraphic
[B]As I understand it you have aftermarket rims. You should know what is on your car! Some of the high end late 16" factory rims were specifically made for front or rear. This does not apply on the aftermarket. The diffrence was in the offset of the rims. The rear offset was adjusted slightly outboard on the rears of the end specific rims. I read somewhere that this was to accomodate the aluminum rear brake drums which were thicker than the steel drums.

Unless there is a difference in the offset on your aftermarket rims (I doubt it!) then there is no reason that any rim couldn't fit on any hub... (not accounting for unidirectional tires).
[/i]

You're mostly right. The front-rear-specific factory wheels were done to keep the wheel faces in the same plane. In other words, to maintan the same front and rear track. Keep in mind, these cars were designed for much smaller 14' and 15' wheels originally, and the different track widths didnt' make much of a difference.

Many aftermarket wheels can be had with the stock-style front-rear offsets, and the same thing applies. This sounds like what you have. If so, Crazy Hawaiian is 100% right on.

What I did when I ordered my wheels was to get all front (0" offset) wheels. When mounted on the car, the rears are just barely under the fender lip, while the fronts tuck about 3/4" deeper. With the stock wheels, they both tuck in.

 

I guess the bottom line is that he needs to check the documentation of the rims he has on the car for backspacing. If he doesn't have the paperwork that came with the rims then he will need to pull at least a couple of the rims and check the offset using the straight edge and ruler method...

 

"Stock 16" wheels (that are cast with front and rear) are 16x8 front with 4.5" backspacing and +0mm offset, and the rears are 16x8 with 4.5" backspacing and +16mm offset."


I agree with what everyone is saying about the different offsets for front and rear. But to help this guy out it would be best to tell him where the deeper backspacing goes, the front or the rear? I'm not sure myself. Also, I think CrazyHawaiian made a small mistake with the info he gave. How can a rim have the same backspacing, yet have different offset? I think one rim has 4" backspacing.

 

On factory 16" wheels, the back spacing is different front and rear. Don't believe me, try a rear wheel on the front. I think that the fronts are 4.5" and the rears are 5". The thing that a lot of people do is, put a set of fronts on all 4 corners. The fronts fit the rear, but the rears damn sure dont fit the fronts (without spacers).

 

This is from the Thirdgen.org FAQ section:

Q: What are the offsets for the front and rear 16 inch wheels?

A: 0 mm on the front and 16 mm (negative - outward) on the rear.



The rear drums are offset toward the outside of the rim about 5/8 of an inch per side. In other words if you had the rims placed curbside down and measured the distance from the inside (topside) edge to the backside of the hub (the surface that contacts the hub of the car) the rear would be 5/8" deeper than the front. That is, if the rims were built with identical specs to stock.