Tess' tire question

[Joe Elliott <jee@domain.elided>]

At 1:59 AM -0500 3/19/02, alfa-digest wrote:
>Recently I've been driving a friend's 356, which, admittedly, I'm
>still not that familiar with, but I'll state up front it is an
>eminently tossable car. We had this one argument about inducing oversteer,
>which he won after a scientific test, but I still can't figure out why.
>
>Not being able to get the rear end to kick out, he wanted to raise the
>front tire pressure. I said no way, he needed to lower the *fronts* to get
>more patch so steering input would be greater. We lowered, and lowered,
>and lowered the fronts (all the while with him smirking that I was just
>wasting my time), and finally even raised the *rears*. The car still
>understeered like a pig! Then he went back to his original starting point,
>and raised the front just 2 psi. After that we were both able to kick the
>rear end out with barely a sneeze.
>
>Why?

Hmm.  I've always taken this for granted.  Before I made the effort 
to adjust the GTV6's caster* to make things more neutral (having 
added a stiffer front bar), I used to run 7psi higher in front.  When 
I read Tess' original post my response to "Why?" was "because 
higher-pressured tires grip more."  But now it occurs to me that I 
can't say why.  I suppose maybe it has something to do with the 
sidewalls of the lower-pressured tire being more flexible as a result 
of their lower pressure?  Does it just have to do with there being 
less *pressure* on the road from the lower-pressured tire?  That 
doesn't make too much sense.  Oh well, it's past my bedtime.

Joe Elliott
'82 GTV6
* for those of you that saw me spin/almost ran into me the first time 
I had open track in front of me in Nashville, now you know why--first 
time at speed with the new caster settings--well, it sure didn't 
understeer anymore--oops.

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