Wheel questions

[Ti Kan]

iain.atkinson at tesco.net writes:
> i have the offer of upgrading the 15 inch rims that i have on my 90 20v q to 17 inch, any ideas what effect this will have on ride and handling and also gearing???

If you keep the rolling circumference about the same by using tires
of a lower aspect ratio, then it would have negligible effect on gearing.
I believe your stock tire size is 205/60-15.  Using my handy tire size
calculator program, I get the following close matches.

Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
205/60-15         4.8in  12.3in    24.7in         77.6in        817        0.0%
205/50-17         4.0in  12.5in    25.1in         78.8in        804        1.6%
205/45-17         3.6in  12.1in    24.3in         76.2in        831       -1.7%
215/45-17         3.8in  12.3in    24.6in         77.3in        819       -0.3%
225/45-17         4.0in  12.5in    25.0in         78.5in        808        1.2%
205/55-16         4.4in  12.4in    24.9in         78.2in        811        0.8%
215/50-16         4.2in  12.2in    24.5in         76.9in        824       -0.9%
225/50-16         4.4in  12.4in    24.9in         78.1in        811        0.7%

The first line is your stock size as a reference, the "difference" column
for the other sizes is relative to the stock size.  It reflects the
change in overall gearing (and error in your speedometer reading,
assuming that it's accurate now).  A negative number means that the
car will be going that percentage slower than what the speedometer
indicates.  If your stock tire size is not 205/60-15 then this column
will not be correct.

I am not sure that the 225 width tires will actually fit your car without
rubbing, but it's listed here for comparison purposes.

Note that going from 15 to 17 inch wheels constitutes a "plus 2"
conversion and going to tires of fairly short side walls in order
to maintain the rolling circumference.  This will result in better
turn-in feel but increased harshness in the ride quality.  The actual
change depends on the tire choice and suspension setup.

I also listed some 16 inch tire sizes above for your reference.
I think that for your car this may be a better compromise for everyday
street driving, because the sidewalls are not as radically short.

-Ti
2003 A4 1.8T multitronic
2001 S4 biturbo 6-sp
1984 5000S turbo
1980 4000 2.0 5-sp
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