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Old 08-31-2012, 02:18 PM   #1
vms150
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Default Trying To Understand Offset

So I read the Offset Info thread and I am still a bit in the dark. Offset is listed as how far the mounting surface of the wheel is from the center of the wheel, and it is listed in mm. Is this correct? If this is correct the less offset, the more aggressive the fitment is right? So the lower the offset number the more "concave" the wheel will have?

So example. A 9" wheel with 50 offset would be pretty standard and not aggressive but that same 9" wheel with 25 offset will be quite concave and aggressive... is this all right?

Finally is there ever negative offset so the mounting surface is further in past the center of the wheel?

Please don't flame, I searched around and am trying to double check what I believe I understand. Thanks guys.
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Old 08-31-2012, 03:09 PM   #2
sc00by4life
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Quote:
Originally Posted by vms150
So I read the Offset Info thread and I am still a bit in the dark. Offset is listed as how far the mounting surface of the wheel is from the center of the wheel, and it is listed in mm. Is this correct? If this is correct the less offset, the more aggressive the fitment is right? So the lower the offset number the more "concave" the wheel will have?

So example. A 9" wheel with 50 offset would be pretty standard and not aggressive but that same 9" wheel with 25 offset will be quite concave and aggressive... is this all right?

Finally is there ever negative offset so the mounting surface is further in past the center of the wheel?

Please don't flame, I searched around and am trying to double check what I believe I understand. Thanks guys.
Concavity of a wheel is all based on the design of the wheel. Lower offset doesn't always mean concave and big lips.

Yes there is negative offset, but you don't see that on our cars.
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Old 08-31-2012, 03:22 PM   #3
vms150
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I have stock BBS wheels on mine and they will remain on there for as long as I have it. This is purely for understanding and knowledge.
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Old 09-01-2012, 12:25 AM   #4
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Your understanding is pretty much correct. As scooby4life said, though, a more shallow offset doesn't necessarily mean the wheel will be more concave. I used to have '95 Cobra R wheels on my Mustang. Ford made two versions - the original (part number ending in -R58) with a +24mm offset, and a version to fit on the rear of older Fox body cars (-M179) with a +36mm offset. The face of the two wheels was identical, but if you looked at the mounting face from the back of the wheel you could see it was noticeably thicker on the R58 wheel. Thicker mounting face = wheel pushed out farther = shallower positive offset.

You don't see negative offsets that often nowadays (at least, not in my experience), but there are wheels out there with negative offsets. From what I've seen I think that's primarily a truck thing.
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Old 09-01-2012, 12:48 AM   #5
SparkSilver10NM
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I have a specific question: I have also searched and gotten some conflicting information so I'd like to get clarification.
I have a 2010 wrx on stock wheels (17x7) +53 offset
I'd like to put a set of 2011 wrx stock wheels on (17x8) +53 offset. But doesn't that mean the wheel is gonna stick out almost an inch? And thus put undo stress on my wheel bearings wearing them faster? O and look kinda stupid too?
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Old 09-01-2012, 03:33 AM   #6
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just a hypothetical question. trying to understand the whole offset thing as well. has nothing to do with rubbing, bearing wear, type of car its going on, etc; simply trying to understand how the number is in correlation to the wheel itself.

say you have two sets of identical wheels (17x7.5 et53 and 17x8.5 et53). now the numbers is the same, except the width of the wheel. to get the 7.5 wheel to sit at the exact same point as the 8.5 wheel, spacers would be required, right? does that in essence drop the 7.5 wheel to a et28?

sorry if this makes no sense at all, it sounds better in my head, i swear!
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Old 09-01-2012, 01:51 PM   #7
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Quote:
Originally Posted by SparkSilver10NM View Post
I have a specific question: I have also searched and gotten some conflicting information so I'd like to get clarification.
I have a 2010 wrx on stock wheels (17x7) +53 offset
I'd like to put a set of 2011 wrx stock wheels on (17x8) +53 offset. But doesn't that mean the wheel is gonna stick out almost an inch? And thus put undo stress on my wheel bearings wearing them faster? O and look kinda stupid too?
Quote:
Originally Posted by Xer0 SiN View Post
just a hypothetical question. trying to understand the whole offset thing as well. has nothing to do with rubbing, bearing wear, type of car its going on, etc; simply trying to understand how the number is in correlation to the wheel itself.

say you have two sets of identical wheels (17x7.5 et53 and 17x8.5 et53). now the numbers is the same, except the width of the wheel. to get the 7.5 wheel to sit at the exact same point as the 8.5 wheel, spacers would be required, right? does that in essence drop the 7.5 wheel to a et28?

sorry if this makes no sense at all, it sounds better in my head, i swear!

To both - yes wheel width effects face position of the wheel. However you are both sort of off. Wheel width gets added to BOTH sides of the wheel, not just one.

The difference between 17x7.5 +53 and 17x8.5 +53 is only half an inch in terms of the outter position of the wheel.
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Old 09-02-2012, 10:35 AM   #8
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Thank you very much for the clarification guys. It was very helpful.
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Old 09-02-2012, 04:36 PM   #9
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Scooby,

So this means if I fit the 8" wheel it'll only carry 1/2" further out from the car? This will not cause any undo strain on wheel bearings? What about turning radius and rubbing when on the terrible Albuquerque streets?
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Old 09-02-2012, 04:52 PM   #10
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Quote:
Originally Posted by SparkSilver10NM View Post
Scooby,

So this means if I fit the 8" wheel it'll only carry 1/2" further out from the car? This will not cause any undo strain on wheel bearings? What about turning radius and rubbing when on the terrible Albuquerque streets?
compared to a 7 inch wheel of the same offset, yes.
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Old 09-04-2012, 01:04 PM   #11
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f'en sweet! i think i'll look into making sure they won't rub when turning and get the ones I really want instead of compromising! Thanks everyone!!!
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