Date:         Sat, 15 Sep 2007 19:27:17 +1200
Reply-To:     Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Subject:      Re: was: tire inflation/wind deflection...Now..Who is really
              driving your van?
In-Reply-To:  <000701c7f759$988743a0$02b2d8d1@dhanson>
Content-type: text/plain; charset=iso-8859-1; format=flowed

>   Answer?  The lawyers are driving your van!
>     Vehicles are designed to have understeer, on the advice of the legal
>experts from the car companies.  While it is generally accepted that a bit
>of minor over steer is much more beneficial when trying to control a car
>driven at or slightly over the limits of traction, the legal wizards have
>deduced that automakers can limit their liability by making cars that will
>plow right off the road, front wheels first.
>    Then, in court,  their council can say..."see, the driver simply drove
>right off the road, because he was going too fast or not paying attention"
>Anyone who's over-driven a "piggish" understeering car knows full
>well...once the front wheels break traction, you just become a passenger..
>   In a vehicle with some oversteer (the rear end may lose some traction, but
>you can still steer with the front) you can still control the vehicle..but
>once you really lose it, the rear end comes around and you spin off the
>road...The legal guys HATE that, because the other legal guys can
>say..."Hey, that car spun out, it wasn't my client's fault, it was the car"
>and win cases...
>   So, we get these designed on purpose plowing cars..or in the case of a
>van, we get odd-ball tire pressure specs designed to make the front let go
>first due to under-inflated tires ( for the load)  maybe..
>   Nice of the lawyers and the judicial system to give us "less safe"
>understeering vehicles to drive so they can cover their own butt$..
>   My opinion only..
>   Don Hanson

That may be true of US-market nondomestic vehicles, with their unique
soft settings, but many FWD cars will break into oversteer when
pushed in a tight bend, then the driver lets his foot off the
go-pedal. FWD cars by nature are understeerers; it's the nature of
the beast, as the tires will scrub under power when turned... they
most certainly do not "pull" the car around the corner. Some FWD cars
will oversteer all the time, but hopefully not as badly as my old
Fiat 128... that was a real fright-machine (partly because it wanted
to oversteer even with the slightest steering inputs and partly
because it was so unbelievably flimsy), the tendency probably due to
the rear suspension design.

The softer the suspension, the more marked the understeer tendency.
So cars in the US (& Canada) are more understeer-and-wallow-prone
than the same models elsewhere, and US designs are worse. Which means
that on the same section of road they are far more likely to get into
a situation they cannot get out of. If you'd like a car that handles,
you'd better start lobbying your congresscritters to do something
about this!

Manufacturers' specs are set for comfort; handling doesn't even come
into it, nor does tire longevity. For a smallish to medium car like a
Corolla, or Corona, say, on ordinary 70/80R13/14s, 32PSI will give
better handling and probably better tire cooling. Soft tires flex;
flex causes internal friction; friction causes heat; heat degrades
rubber. I've melted tires on motorcycles, so I know what heat can do
to a tire.
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
Seashell, Macintosh, VW/Toyota van nut
‚ Opinions stated are mine, not of the University of Otago
"There is water at the bottom of the ocean"  - Talking Heads