AutoX and tire impressions

Mon Jun 17 17:26:53 EDT 2002

15" rims are usually lighter than the same width 17" rim.  But as long as
the actual outside diameter of the tires remains the same, the acceleration
should be the same.  The trick setup would be a set of low profile 15" tires
so the diameter was greatly reduced.  The same as a faster rear end (or is
that front end) ratio.  Also it would lower the car with out changing
springs.  But then as the car rolled it might begin scraping the side of the
body.  So, 215/45x15 would accelerate faster than 215/60x15.  Some AutoXers
do a version of this but most lower the whole car with stiff springs and
change the differential gears for faster acceleration.  But I do have a set
of 15" wheels..... and I saw some used rubber.....heh,heh.

Dave

-----Original Message-----
From: Derek Pulvino [mailto:dbpulvino at hotmail.com]
Sent: Monday, June 17, 2002 4:06 PM
To: t44tq at mindspring.com; dfreed at bear.com; dkpriebe at attbi.com
Cc: 200q20v at audifans.com; S-Car-List at AudiFans.com
Subject: RE: AutoX and tire impressions

Dave,

Sorry about the slow response time; I'm back on the limited access computer
front.  In other words, I've got to go to the library to access computers.

As to mods for my car, other than the Eurolights I'm only running a high
tech disco ball on the rear view mirror.  That alone seemed to have shaved
about a half a second for me.  In addition to the disco ball, really the
only thing different from factory is Bilstein shocks.  Not chipped, factory
springs, 215/60-15 tires, etc. although I have gone through the process of
renewing some of the suspension bushings.

I'm curious what others think with respect to this, but I think smaller
diameter wheels might help with time on a short, acceleration laden
autocross course.  I think the weight/rotational inertia reduction helps
with acceleration.  I do remember noticing this when I was running 16's on
my car, more sluggish acceleration.  Comparatively, I autocrossed with the
16's last year, and my time this year was a lot further up in the rankings
than last.  I also know my driving was better this year; too much scrub, and

carrying way too much speed through the corners (aka, a lot of understeer)
last year.  So two variables...

My driving style just involves judicous heel-toeing, and trying to use the
controls of the car to transfer weight.  I can definetly notice the car
breaking loose at either end depending on how I bias it.  I was trying to
break as deep into corners as I could, and get on the gas when the corner
started to open up.  I know there were some spots on the course where I
wasn't using all of the grip of the car, whether that was because I could
have braked deeper, or carried more speed...next time I guess.

I probably won't make it out to Bremerton this weekend, but as I remember,
the week after that the race is on in Everett again.  More likely than not,
I'll make it to that.

dp

----------------------------
My best actual running time was 48.946. But because I run in the Street Tire
class, which any car can run in, a handicapping index called a PAX is
applied. The PAX is based on the SCCA classing handicaping. The link for
these values is at: http://www.scca-chicago.com/solo/indexes/rtp02.html So
within the Street Tire class I end up with the time of 38.423. At least for
the WWSCC, this is the only class I even remotely have a chance in. I wound
up being 13th out of 20 within the class, even though for time overall I was
a lowly 158th out of 171! On the other hand, when I have run at SCCA events,
I do compete in GS, instead of Street Tire, because there are typically only
1 or 2 other entrants, thus improving my chances a bit. Derek, you ended up
with a much better time than me, a full 2 seconds faster! What other mods do
you have besides the Euro-lights? Next time we should get together, and
compare driving notes. I am really curious how other 200s handle
autocrossing. For those in the Seatle area, here is a link for upcoming
autocross events: http://www.wwscc.org/calendar.html It would be fun to have
a few 200s out there. I am planning going to the Bremerton event on the 23rd
and the WWSCC event on the 30. That is of course as long as baby #2, which
is due in 3 weeks doesn't decide to come early.

On a slightly different subject... why I love my '91 200 Avant... what other
car can I make a late night run to Home Depot in, to pick up 4 2"x10"x10'
pieces of lumber, not have to remove the car seat or stroller, and still
pull 1.8 bar on the freeway on ramp on the way home? Simply irreplacable.

Dave Priebe
Kenmore, WA
91 200tqa 156k his
95.5 S6 99k hers

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