1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

rim offset

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Old Jun 27, 2007 | 07:41 AM
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rim offset

n e one know the offset on a gsl se
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Old Jun 28, 2007 | 12:55 AM
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40mm looks great on 7" wheels
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Old Jun 28, 2007 | 01:26 AM
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Offset varies with rim width, backspace is a constant. I don't have any stock SE wheels around to give you either but someone should be kind enough to measure for you. Or you could search, it's listed several different places.
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Old Jun 28, 2007 | 08:50 AM
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Originally Posted by trochoid
Offset varies with rim width, backspace is a constant. I don't have any stock SE wheels around to give you either but someone should be kind enough to measure for you. Or you could search, it's listed several different places.

actually you have it backwards, offset is from the center of the wheel to the wheel mounting flange so width has no impact on it. backspace is from the inside lip of the wheel to the wheel mounting flange.

for example you can have a 10" wide wheel with 25mm offset and 6" backspace, and the same style of 12" wide wheel with the same 25mm offset but the backspace will be 7", the wider the wheel the more backspace, unless it's custom.
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Old Jun 28, 2007 | 02:13 PM
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For a gsl-se, stock wheel backspace is darn close to 4.75". With after market wheels anything more than that gets pretty close to the spring on the front, even with a coilover kit.
On the front of My car I have respeed coilovers and afco springs(standard 2.5 I.D.) , The wheels I'm going to run have almost exactly 5.25" backspace and are only a 1/4 inch way from the spring. I'm most likely going to have ot run spacers on the front. So they don't rub under hard cornering. A half inch of clearance in the front is a good minimum. The back is a different story, one could run 5 1/2 or even 5 3/4 in. of backspace on the rear wheels and get away with it pretty easily. These are according to my measurements on my gsl-se axle and spindles. they have worked for me so Maybe you can get some use from them.
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Old Jun 28, 2007 | 03:36 PM
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From: St Joe MO
Originally Posted by Phiber Optik
actually you have it backwards, offset is from the center of the wheel to the wheel mounting flange so width has no impact on it. backspace is from the inside lip of the wheel to the wheel mounting flange.

for example you can have a 10" wide wheel with 25mm offset and 6" backspace, and the same style of 12" wide wheel with the same 25mm offset but the backspace will be 7", the wider the wheel the more backspace, unless it's custom.
Sorry, I have to disagree with you. The difference between offset and backspace is often confused. Backspace relates to the inner lip and the mounting flange, offset relates to the flange and the center line of the wheel.

When I said backspace is constant, I should have said it should remain constant between wheels for proper fitment. Meaning backspace will remain the same or near the same between different wheel widths, while offset will change with rim width.

Check out this link, it will help explain how to measure wheels and how offst/backspace relate.

https://www.rsracing.com/tech-wheel.html#backspace
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Old Jun 28, 2007 | 04:20 PM
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please forgive me...

Sorry to ask, but I'm still trying to figure out what will actually fit a completely stock GSL-SE. I want a shiny lip with black center (spoke/mesh) to go with the black on stainless of the body. Is there a wheel you can buy that is 15" and around ~6.5" wide and offset of 40 (I noticed a couple brands this size ) that will have all the proper measures to fit my stock car(suspension) with no spacers or fender rolling or anything? Without any clearance issues or excessive wear issues? I've never found a defintive answer, can somebody help? I really want wheels for my car! Thanks in advance!
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Old Jun 28, 2007 | 07:39 PM
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Panasport's recommended offset for a 15 X 7 wheel is 33mm. I'm running 35mm offset 15 X 7 Team Dynamics wheels with 225/50-15 tires. They seem to fit just fine statically -- can't verify the clearance when driven, since my car doesn't run yet : (. If you run 40mm offset, the wheels will be tucked inboard slightly more. If you're running a narrower tire and want the wheels as far outboard as possible, you may be able to go with a 30mm or even a 25mm offset.
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Old Jun 29, 2007 | 10:06 AM
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From: State College, PA
definitive answer

Anybody?
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Old Jun 29, 2007 | 11:58 AM
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Here is a conversion chart that will make everything much easier. It really gets down to you understanding how wheels fit and how to take measurements. This is great stuff to know and understand. Knowing what works it great, but knowing how it works is better. The link is great and has pretty much everything you need to know about fitment. Just stay close to 4.75" backspace and you will be ok.



https://www.rsracing.com/tech-wheel.html
Attached Thumbnails rim offset-tech-wheeloffset.gif  
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Old Jun 29, 2007 | 12:02 PM
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ha! just by looking at the chart I can tell you that the offset on a gsl se wheel right around 38mm(5.5"wheel with 4.75" backspace). !!!! =)
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Old Jun 29, 2007 | 12:08 PM
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oops, didn't see that Trochoid already sent you that link. There's a reason two people have sent it ot you. It's good stuff. I urge one to study up!
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Old Jun 30, 2007 | 09:31 PM
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piston vs rotary? Rotary!
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From: Prescott, Az
what would be the widest tire i could fit without making my car look like ****??????
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