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Old 01-01-2004, 02:09 PM   #1
essogas
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Default STI has a 48mm offset right? Offset question...

I read the offset FAQ. I understand what the offset is but I want to get something straight. If the Sti has a 48mm offset for it's stock BBS wheels ( I think this is right) An offset of greater number moves the wheels further toward the outside of the car? Hence the "rolling" of the fenders? And an offset of lesser number than 48mm moves the wheels closer in toward the wheel well?

I just want to know how to correctly shop for the right wheels and not listen to shops that give you the wrong advice and end up doing damage to your car! Two mm either way is okay? I think I can get some volks that match perfectly.
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Old 01-01-2004, 02:47 PM   #2
STi-ll chillin'
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I'd like this comfirmed too.
Thanks
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Old 01-01-2004, 03:11 PM   #3
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Quote:
An offset of greater number moves the wheels further toward the outside of the car? And an offset of lesser number than 48mm moves the wheels closer in toward the wheel well?
Yes.

But just because some wheel has near the same offset as the STI's stock wheels does not mean that it will fit over the brakes, etc.
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Old 01-01-2004, 07:01 PM   #4
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To help answer a few questions here goes, the stock BBS USDM STi wheels are NOT 48mm. Go and look on your wheels around your lugnuts, the wheel specs are as follows for the stock BBS USDM STi wheels: 17x7.5 with a 53mm offset.

Now the issue of the offset of wheels which doesn't seem to really be the problem, to clear the STi calipers a major factor depends on the design of the spoke of the wheel itself and how/if it can clear the STi caliper. Many wheels would fit the STi (offset/width wise) yet the spokes hit the caliper due to the angle, arc and curve of the actually spoke itself. It seems this is one reason why we have so many different offsets from the various manufactures (depends alot on the style spoked wheel).

For a better understanding of wheel offset, another good thing to remember is that the offset and width of a wheel work together as well as independently when changed, take a look at this link Wheel Offset it will help you see the effects of changing wheels (i.e. clearance from stut housing to the inside of the wheel, along with how much the wheel will extend out toward the fender) when offset and width are changed.

Lastly to make it simple for yourself, if your interested in finding wheels that fit the STi take a look at the link I started below it will help lessen the headaches of figuring out what fits...... Here is a list of available wheels for the STi with sizes/widths/offsets

Hope this helps,
Rick

Last edited by ami2fst4u; 01-02-2004 at 05:07 PM.
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Old 01-01-2004, 08:31 PM   #5
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Default Re: STI has a 48mm offset right? Offset question...

Quote:
Originally posted by essogas
An offset of greater number moves the wheels further toward the outside of the car? Hence the "rolling" of the fenders? And an offset of lesser number than 48mm moves the wheels closer in toward the wheel well?
No, it's the opposite. A smaller offset will move the wheel toward the outside, a larger offset closer toward the car.

In other words: If your offset is too small, you will rub the fenders (which you might be able to work around by rolling them). If your offset is too large, you will rub on the inside.
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Old 01-02-2004, 03:10 PM   #6
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Ditto what jblaine, ami2fst4u and TheWRX have said. The curve of the wheel spokes is critical for fitment. I would try to stay with a +48mm offset or greater with the stock wheel being +53mm, but as ami2fst4u said, wheel width also comes in to play with offset. Beware of using spacers they reduce the offset (ie. +48mm offset with a 5mm spacer = +43mm offset) and they may require longer studs (>+5mm spacer). Those deep-dish wheels you see on RWD cars are actually sporting negative offsets. Check out ami2fst4uís link for wheels that fit a STi.
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Old 01-02-2004, 03:30 PM   #7
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Default Re: Re: STI has a 48mm offset right? Offset question...

Quote:
Originally posted by TheWRX
No, it's the opposite. A smaller offset will move the wheel toward the outside, a larger offset closer toward the car.
How do you figure?



Shrink the offset line in that picture. Where does the wheel move? In toward the chassis, not out toward the curb.
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Old 01-02-2004, 05:03 PM   #8
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Default Re: Re: Re: STI has a 48mm offset right? Offset question...

Quote:
Originally posted by jblaine
How do you figure?



Shrink the offset line in that picture. Where does the wheel move? In toward the chassis, not out toward the curb.
Well the fixed point here (in relation to your car) is the hub where it is firmly attached via the lugs. If you shrink the offset to zero, the wheel is, in fact, no longer offset and the centerline of the rim is even with the hub mounting surface. The wheel rim would then in effect be moved out away from the car toward the street side.

Positive offset means the wheel rim is inset toward the car, negative offset hangs the wheel out in ghetto goodness. Check out ami2fast4u's link above as many here have already gone through the Great Wheel Search for the STi.

Last edited by Mister Toro; 01-02-2004 at 05:10 PM.
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Old 01-02-2004, 05:44 PM   #9
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As I previously posted look at this link Wheel offset calculator... which although doesn't show pictures of the affects, it will tell you the clearance from strut housing to the inside of the wheel, along with how much the wheel will extend out toward the fender when offset and width are changed. Which personally I think gives a simple understanding of the affects in changing wheels.

Depending on your offset and width combo you choose, it can/will affect clearance issues BOTH ways some being more extreme than others, it won't just affect one way.

Rick

p.s. Nevertheless back to the topic, essogas go here to see a list of available wheels for the STi with sizes/widths/offsets
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Old 01-02-2004, 06:18 PM   #10
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Quote:
Originally posted by jblaine
How do you figure?



Shrink the offset line in that picture. Where does the wheel move? In toward the chassis, not out toward the curb.
You're reading the thing wrong. When you "shrink the line" that means you have to actually move the hub mounting surface farther in to shrink it. lower offsets stick out farther.

Subaru uses wheels with positive offset. +53 will be closer to the inside than +48. Read the Tirerack.com explanation of offset. it is correct.

http://www.tirerack.com/wheels/tech/offset.htm
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Old 01-02-2004, 11:11 PM   #11
essogas
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Okay, so we know some things:
positive offset moves wheels inward and negative offset moves wheels outward. But regardless of the caliper clearance with the STi, let's set it aside for the moment. (I realize it is a big issue) I'm more concerned with the performance effects on a car with the wrong offsets. The question remains: Just because dfferent offsets and rim widths will work with the STi, or any car for that matter... What is the disadvantage, if any, of having offsets that DO NOT match the manufacturers specs?
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Old 01-02-2004, 11:18 PM   #12
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I don't see gram lights in the 18" on that list. Won't they fit?
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Old 01-03-2004, 12:06 AM   #13
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What is the disadvantage, if any, of having offsets that DO NOT match the manufacturers specs?
Increased scrub radius, which is a bad thing. You go down the path from sweet, precise handling feel to grips well, but feels like crap.

Search this site and Google on terms like "scrub radius" and "king pin inclination" and you'll learn more than you ever wanted to know.
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Old 01-03-2004, 12:37 AM   #14
EHobron
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Finally, the truth! Thanks Jon Bogert!

By the way everyone, the Tire Rack's explanation of offset is correct but the final statement that maintaining stock offset will not work on all cars is wrong. Stock vehicle, stock suspension, and stock geometry means stock offset, period. Too many people are playing with offset to compensate for big wheels and tires.

The statement should read, "not all cars can use wider wheels." Probably bad for sales though.

Nuff said!!!!!
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