ratio411

I am looking at some 18" rims for my Camaro...
I am really particular about how they will sit under the car. I don't want them out like roller skate wheels, but I don't want them sunk way under the car to where I end up needing spacers. Worse yet would be running into problems with rims/tires hitting parts of the car.
Anyway, it used to be so easy when you figured all this by backspacing measurement in inches. Now all I am finding is wheel width in inches, and 'offset' in metric.
I know what offset is, and how it works, but I am having trouble determining what will fit proper because of the inch width and mm offset.
Anyway, what offset do Y2K SS rims have?
What is the rated width for the Y2K SS ten spokes?
If I get these 2 questions answered, I will be half way to being able to figure things out.
I need factual figures though, no guesses.
I have these rims now and I want to go to 18"s and would like to go a little wider. I want the new rims to be no further under the car when installed, and no more than 1/4" further to the outside, looking at the face/sidewall.
Any suggestions?
If I am looking at 18x9.5 Z06's, what offset?
50 mm, 56 mm, 58 mm, 61 mm, or 64 mm?
How about 18x10.5s?
I have found these size replicas in all these offsets.
Thanks much!
Sorry so long!
Dave

Xsta Z 28

iTrader: (2)

Stock SS wheels are said to have a 50 MM offset.

Here are some other popular sizes - I cannot vouch for the accuracy I found it on the internet.

Various Rim Dimensions

Rim Name Size Offset Backspacing Suggested Thickness (3rd Gen)
Corvette 84-87 16x9.5 38mm 6.6" 2"
Corvette 88-96 17x9.5 56mm 7.3" 2.25"
Corvette GS ZR1 style 17x9.5 50mm 7" 2"
Corvette ZR1 style 17x9.5 38mm 6.7"
Corvette ZR1 style 17x11 36.5mm 7.397" Rear
Corvette Grand Sport 17x9.5 56mm 7.4" 2.25"
Corvette Grand Sport 17x11 50mm 7.93" Rear
C5 Corvette 97-2000 17x8.5 front 56mm 6.8"
C5 Corvette 97-2000 18x9.5 rear 63mm 7.6"
C5 Corvette Z06 17x9.5 front 54mm 7.2"
C5 Corvette Z06 18x10.5 rear 58mm 7.9" Rear
Camaro 82-92 16x8 front 0mm 4.35"
Camaro 89-92 16x8 rear 16mm 5"
Camaro F1 ZR1-style 17x9 50mm 6.8"
Camaro 93-97 16x8 55mm 6.5"

The closest you can get to 50mm and possibly even less the better.

David N

Don't want to hijack this post, but I'm also confused.

Let me start with Z06 10.5" rear rims as an example:

+58 mm offset, 8" backspacing, stock Rim, requires spacer

+36 mm offset, 7.4" backspacing, aftermarket Rim, manufacturer claims no spacer is needed.

To make the Z06 stock rim fit, most people are running a spacer. I've looked at the diagrams showing what backspacing is, won't that increase the wheels backspacing? So, how can it be that the aftermarket wheel with less backspacing fits. Shouldn't this rub the inner wheel well.

ratio411

Xsta: Thanks for helping out some!
I have been doing some of the same research online and I am coming up with the numbers you are. I have also found that there is a very large selection of offset among the replica rims. That is kinda what has me confused... but I am getting close to figuring it out.
I checked AR's site and found that TT2s for our cars have only one offset available, and that is the deepest backspacing that the rim is made in. Well, IMO every Camaro I have seen with TT2s looks like the rims are sticking out too much for my taste. So I have ruled them out as an option. I will note that on a T/A, TT2s look absolutely perfect. I don't know why one looks right and not the other. Anyway, I found a site that listed both offset and backspacing for it's replicas. Like I said, each rim size has 5 to 10 different offsets to choose from. I have it pretty well narrowed down to Z06 18x9.5 on all four corners. Looks like 58mm offset will best suit my tastes. 50 is described on the site as "not suited for lowered Camaros as they put the tire very close to the outside body panels", in other words, they stick out a little. For slightly lowered Camaros, they list a 53 in this rim. Then for lowered Camaros they specifically recommend 58 or 61. So I figure 58 since my car is almost 1.75" lowered. As a side note, they also have the replicas in 38, 64, and 68 offset. Another Vette replica size or style (forgot), has offsets in the low 30s and mid 70s!
This info is more or less what I was hoping some wheel experts on this site could clear up for me. I was wanting to get very Camaro specific.
Dave: The reason that 8" bs needs a spacer is to push the rim out from under the car a bit. What that number is saying to you is that the back of the rim, looking at it like a dish, is 8" deep. The rim that is 7.4" is more than a half an inch shallower. That .6" is displaced towards the outside of the car when compared to the other rim. It would look the same on the car as the 8" bs rim with a .6" spacer behind it. Only the spacer is effectively built into the 7.4" rim.
Hope this makes sence.
In short, the backspace measurement tells you how far the rim will tuck under the car. The bigger the number, the further under the car. The smaller the number, the more towards the outside they are, and the bigger/deeper they appear.
Dave

David N

Thanks Dave, that was a clear explanation, the light bulb went off. One more quick comment/question: since the width of the wheel is constant, but one can have different backspacings, the depth of the face of the rim must also change. So, will you see a .6 " deeper lip with a 7.4" backspacing vs. 8"? Or do they make the rim lip wider where one bolts the rim to the car?

Xsta Z 28

iTrader: (2)

To throw in even more confusion for you.

My 17" x 9.5" FIKSE FM-5's have a 37mm offset
My 18" x 9.5" & 10.5" FIKSE Profil 13s have a 38mm offset.

I had 18" x 9.5" and 18" x 10.5" Z06 wheels on my SS. Looked awesome, but the large offsets 56mm and 58mm kinda caused the wheels to be too deep into the wheel well. The fronts fit wil no proble. The backs did rub a little on the inner wheel well, but nothing a little hammer couldn't fix. I did wind up running a 5/16" spacer purely for looks. Oh and FYI the use of a spacer would reduce the backspacing and also the negative offset.

So more confused?? I know I am. But all in all I LOVE my FIKSEs!!! Although with a lowered car the rear passenger side tire does tend to rub the out wheel well lip, on some nasty bumps.