Wheel size suggestions needed ASAP for my 1990 AudiQuattro Coupe....

[Grant Lenahan]

I dont think so.  Offset is measured from the *center*.  The center never 
moves :-)
Rather, width is added to each side fo the centerline.  See the nice 
diagram on Tire Racks site if you doubt this.

Am I wrong?  (certainly possible, but Proof please.)

Grant
At 12:35 PM 8/25/00 -0500, Todd Young wrote:
>I beg to differ on this point. If the new wheel is wider than the old, you
>would want to increase the offset by exactly half of the difference in width
>between old and new. That way you would maintain the steering center.
>
>Grant Lenahan wrote:
>
> > At 09:59 AM 8/25/00 -0700, ACAdelhoch wrote:
> > >I am ready to purchase 8x17 wheels for my Audi, but am not 100% certain of
> > >the offset needed. I think the factory offset for the 7x15 speedlines are
> > >37mm, but should I change the offset if I go with larger wheel width?
> >
> > For most neutral handling, you want to maintain the *smae* offset, since
> > that keeps the steering center where it was intended to be.
> >
> > The fly in this logic is that some cars need to set the wheel further out
> > to avoid rubbing a suspension component, but you didn't specify the car, so
> > no one knows (except those who have your stable memorized :-))
> >
> > >Please let me know what the correct offset should be on an 8x17 wheel.
> >
> > See above.
> >
> > >I am going with 215/45 r17 tires if using 8x17 wheels. Does this sound
> > >right? I used the aspect calculator and found this tire size to give the
> > >closest match to PLUS 2 upgrade.
> >
> > geometry solves this one.
> > effective radius = wheel Radius + sidewall height
> > sidewall height = width * aspect ratio
> > circumference = 2*pi*r
> >
> > Grant
> > ==========================================
> > Grant Lenahan
> > glenahan at telcordia.com
> > gfl at erols.com
> > gfl at alum.MIT.edu
> >
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>
>--
>-----------------------------------------------------------
>Life's a beach. Dig your toes into the sand and enjoy.
>-----------------------------------------------------------
>Todd Young              WAM!NET Inc.
>tyoung at wamnet.com       655 Lone Oak Drive, Bldg#A
>651-256-5051            Eagan, MN 55121
>800-585-1133 ext.5051   http://www.wamnet.com/
>'93 Audi 90S(|___\====OOOO====/___|)

==========================================
Grant Lenahan
glenahan at telcordia.com
gfl at erols.com
gfl at alum.MIT.edu