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Re[6]: tire pressure

To: Tor Hval <torhv@ifi.uio.no>
Subject: Re[6]: tire pressure
From: rebean@CCGATE.HAC.COM
Date: Thu, 04 Jun 98 18:31:57 PST
     


>We will have to investigate the roll-bar setup, before we eventualy change 
>the setup. But I suspect that we have stock roll-bars.

The stock Elans (all of them) come with one rather small one at the front 
and none in the rear.

>We did not have in mind to buy/make a lot of different roll bars. We are 
>probably going the low tech rout and will tweek the chassis by
>tire pressure :)

That will work fine.
     
>When it comes to tirepressure, I just spoke with my father about 
>tirepressure on the phone.
>He was quite a bit sceptial about
>using as high  tirepressure as was recomended by you(36 front, 26-32 
>rear). He was worried that the contact patch of the tire would become 
>much smaller, and that it would speed up tirewear a lot.

If the wheels are wide enough with respect to the tire width, to have a 
stiffening effect on the sidewalls, you could use less pressure.  Also, 
you may find, if you have very wide tires, that any one tire doesn't carry 
a lot of weight and therefore wouldn't require as much air.   But 18 is 
quite low.

>He also would not buy the story that we can ignore the tirepressure 
>recomendation from Lotus. Because if Lotus is quoting a "suboptimal" 
>tirepressure, to avoid lawsuits, there must be some danger of using 
>"optimal" tirepressure. What can Lotus(or any other manufacturer be sued 
>for) if they quote "optimal" tirepressure?

Stock tires for your car (it was a S4, right?) were 155 x 13.  Even with 
those, I remember that the recommended pressure was grossly inadequate.
     
As for the law suit issue, manufacturers assume, and often make provision for, 
gross incompetance.  So they "idiot-proof" many things.  They'll often set the 
front camber positive to promote understeer regardless of compromising driving 
enjoyment, for example (not saying that Lotus does this).  The tire 
recommendations are just more of that.  It's a matter of their priorities vs. 
the priorities of the typical performance driver.

What I'm saying is that "optimal" is subject to interpretation (Whose optimal?).

Have a nice weekend.  I'm leaving work now.  I plan to get my Elan driving fix 
tomorrow by going somplace.  Hope you two can do the same.  :-)

Rod
     


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