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Discussion Starter · #1 ·
I know that this topic has been discussed before, but I've done searches and can't find the exact info.
I'm ready to buy some wheels and I'm pretty picky, so the only rims that I like and can afford come in these sizes:

bolt pattern=5x120mm (I've heard this will work from several people. 4.75=120.65mm)

Front: 17x8.5--offset=15mm (so 4.84" backspacing) is that too much backspacing for the front? Will I need a spacer?

Rear: 17x10--offset=13mm (so 5.51" backspacing)

If these won't fit, then I can use the front for the rear and buy these optional for the front.

Front: 17x 8--offset=35mm (so 5.3" backspacing)

I really want the staggered look wider and deeper dish in the rear. I really don't want to modify anything. Will I need spacers? Will the tires stick out too much? What size tires?
What size is the center bore on our stock rims?
Any help will really be appreciated. Wheel/Tire shops don't help at all--it seems like their knowledge of there chosen profession is very lacking.
sorry so long
 

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The bolt pattern may work with slight machining, without it, I severly doubt it.

None of those sizes will fit, took much RS (rear spacing). Anything remotely close to 5" will rub the frame.

As an example, the GTA replica wheels (GNX) have a 0mm offset, which is roughly 4.5 RS. These are very close to the frame. The best chance you may have is the wheels with 4.84 RS but again, I doubt it and I hate to see you order the wheels and then not be able to return them.

You could always measure using a piece of cardboard with holes in it for the wheel studs then using a ruler measure back from the cardboard to the frame.

good luck...feel free to ask more questions!
 

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Discussion Starter · #3 ·
That is what I was afraid of even though I have read of people using 5.5" backspacing. I don't know if they used spacers or notched the frame--they didn't mention that. I will measure today, like you said.

If I use the 4.84 backspacing on the rear I will use the others on the front---What is max backspacing for the front, that will be hard to measure.
 

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Discussion Starter · #4 ·
Well, I went out and measured. It took awhile to make the template, but I made it right (I have alot of drafting tools.)

I have about 5 5/8" (5.625") from the frame to the card board cut out.

I still don't know what will work though. I know I have to account for how much the tire sticks out. I will have to order them, so I cant just go and try them on. Is someone running something similiar.
PLEASE speak up.
 

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.38 - I think some people have used spacers and/or notched with frame with good success. You can always ask whom ever you order from, "as long as I don't mount tires on these can I try the fitment and send them back if they're close?"

Good deal on making the template. Did you make something that was at least 17" in diameter? If so, then did you measure the entire radius of both sides of the "wheel" template. If that's the case, then you might have room. As a guideline, a tire on average sticks out .25" to .50". Let me know how you make do. Later...
 

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Discussion Starter · #6 ·
Nobody at any tire/wheel shop can give me any answers. They try to tell me that I have a different bolt pattern than 5x4.75. I don't know where they get there info.
I'm not worried about using a spacer. I won't be racing on these rims.
I will probably order one first and see the fitment. And send it back if it doesn't fit. I'm in Texas and they are in N.C. I don't want to pay shipping twice.

So what about the backspacing in the front? Anyone?
 

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Discussion Starter · #7 ·
Oh, does anyone know if 5x120mm bolt pattern will work for sure.
 

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The backspacing of the stock T wheels is 3 3/4" and the GN wheels are 4" (or is it the other way around). Anyway I have 16x8 wheels with 4" backspacing all around. On lock-to-lock turns the front wheels hit the frame.

I think the ideal BS (Backspacing) would be 3 7/8". Depending on the width of tires. I use 255/50/16 for the rears which end up being a little under 10" wide. For the fronts I use 215/60/15 which are 8" wide.

Can you find out what cars the 120mm wheels fit from the wheel guy ? That may help to confirm if it is just a rounded conversion of imperial to metric.

Ideally you should get wheels that are marked, measured and sold as 4.75".
 

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Discussion Starter · #9 ·
I was almost sure that our t wheels have 4.5" of backspacing. I have heard that from at least 2 very knowledgable GN gurus. But, I will measure tommorrow to see for sure.

The guy at the wheel place says he has sold 5x120mm to monte carlos and others with 5x4.75, he can't gaurantee they will fit, but hasen't had any returned. But he is also trying to sell me something.
Alot of people put these particular rims on BMW 5 series-If that helps.
 

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Discussion Starter · #10 ·
I couldn't wait until tomorrow. I went out and pulled a wheel and measured. My T rims have in between 3.75" and 4" backspacing (its hard to get an exact measurement). I was wrong, They were wrong. You were right.
But, Mike you said you running a 215/60/15 on a 16" rim. I think you ment a 215/60/16. Anyway that is a pretty tall tire, in combination with a taller wider rim. I think that could be why you are rubbing on hard turns instead of the backspacing. But, I could be wrong.
 

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Discussion Starter · #11 ·
anyone else?
I still need to know if 5x120mm will work.
 

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I am curious as well does anybody know if 5x120mm will work for sure?
 

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120mm=4.7244094" This is not 4.75 Studs are designed to sit in the CENTER of the rim holes not off center. You will be putting unequal stress on the studs and good chance they will break or cause wheel loss. So this is why I see Monte guys put there wheels on with a big hammer crazy
 

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Discussion Starter · #14 ·
I just did a search on the F-body sites and found out that alot of them are using this bolt pattern. The difference is 0.65 mm which is approx. the width of a hair.
It may not be the best idea, but I think I'm gonna take my chances. I'll just keep the lugs torqued really tight all the time.

Thanks everybody for all the help. It may take a while because I am gonna buy tires and get just a little body work done (a little tree ran behind me while I was backing out. But,I will post results and pictures when I am done.
Thanks again.
 

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Can we have an update and some pics to please. I'm also in the wheel market and would be interested in what backspacing you finally settled on.

:headbang: :6:
 

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Tire/wheel fitment worksheet...

I made up this simple worksheet to assist in determining wheel backspacing and tire clearances. It helped me keep it in a simple one page format. Custom wheels and tires need to be right the first time. Measure, measure again. Then measure again. Just before you order measure one more time.

Hope this helps someone. If you see any mistakes, let me know. It's primarily for the rear axle, obviously.


http://community.webshots.com/photo/109755794/148118162doyOFz

It's a JPEG. Hit "view full size" and print a copy to work from.

This tire calculator helps, too!
http://www.1010tires.com/TireSizeCalculator.asp
 
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