Re: Wheel Fantasy

[audidudi@delphi.com (Jeffrey J. Goggin)]

>
>     According to the 1995 MAST Fitment Guide published by Michelin North
>     America,
>
>     "When the mounting face is toward the wheel's streetside, the wheel
>     has POSITIVE offset.  Negative offset occurs when the mounting face is
>     closer to the brake side of the wheel."

Perhaps the terminology is used differently elsewhere in the world but I
suggest the above is wrong: If the wheel mounting face and rim center are in
the same plane, the wheel has zero offset; if the mounting face is located
inside of the rim center (toward the center of car), it has positive offset;
if it's located outside the wheel center (toward the outside of the car), it
has negative offset.  The confusion is generally caused because
manufacturers tend to quote wheel offset in mm without respect to being
either positive or negative.
Or they just skip the issue entirely and quote backspace, leaving it up to
you to calculate the offset...

>     Therefore, the lowriders have NEGATIVE offset and our Audis have
>     POSITIVE offset.

Wrong ... see above.  Or just order some custom-made wheels for your 5ktq
and be sure to specify that you want "positive" offset...  ;^)

> With all of the wheel discussions here we should be carefull that the
terminoligy is common and correct.  Do > you have a different source that
states the opposite??

Agreed.  I can cite several sources but the only commonly available one is
Fred Puhn's "How to Make Your Car Handle" by HP Books: check out Figure 34A
on p. 126.  BTW, this is a good primer on the subject ... not very detailed
with regard to design or racing applications but it explains the terms and
concepts involved pretty clearly and concisely.

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