[urq] Alternat wheel sizes and matching tires for 1985 ur-q

[Eric Renneisen]

Ed Kellock wrote:
> Regardless of wheel, the main issue with using 
> the same tires/wheels on both the urq and the 
> S-car is stock original diameter.  They are 
> over an inch different.  

I'm having this exact same dilemma right now.  I need tires for the urq
and the S4, and I've now got three sets of wheels (15x8, 16x8, and
17x8).  I'd like to use the 16" as track wheels for both cars and I
might swap the 17s between them just for fun.

Now, the stock S4 tire diameter is almost identical to the tire used on
the 15x6 urq wheels.  However, the stock size for the 15x8 is about 5%
smaller.  Maybe I missed it, but I didn't think there were any driveline
differences between ->'83 and '84+.  Does this mean the later cars were
effectively geared down?  Hmmm, that might have helped with turbo lag
complaints.  I know there are differences in the speedo cable for the
different instrument clusters, but was it adjusted for the shorter tires
(not that a 5% or more error would be unusual for an Audi speedo).

The bottom line is that I don't want to gear up the urq with taller
tires.  The S4 (bone stock for now) probably wouldn't feel too bad with
the shorter rubber, however I don't want it to look any wackier than it
already does (insert "Allroad package" joke here).

Also, I'm looking for the optimum width (performance, not comfort) to
run on these wheels.  Does the sidewall height play a role here?  i.e.,
would the optimum width for the 15x8 be different from a +2 setup on
17x8?

Eric Renneisen
'93 S4
'86 urq
Chattanooga, TN