Tire Heating

["Al Powell" <APOWELL@agcom.tamu.edu>]

Mr. LToy writes:

> Actually, I think LOW pressure can cause more heat buildup problems due to
> excessive flex and increased rolling resistance (= friction=heat).  "Try" it
> sometime, just around town (BTDT--see, I get the "opportunity" of dealing
> with a diff'rent rental sled every month or so--sometimes they're a bit low
> on air)

EXCELLENT point!  You're right in this respect - low pressure 
does lead to more flexing, which  will certainly generate heat and 
therefore is to be avoided.  Of course, the handling also goes in the 
dumper...(such an elegant but descriptive phrase..)  That flexing 
certainly can't be any good for the tire's inner construction (belts 
and bonding) either!!

Thinking further, running a few pounds high reduces flexing somewhat, 
so I kinda wonder which would generate MORE heat under identical 
conditions -  X pounds low or X pounds high?  Seems like if a tire 
would fail at Y pounds pressure, you might be closer to that 
failure point if you run high pressure and tire heating adds a few 
pounds as a result of heat-related expansion.

Seems like a rational center point is a good thing to find....

> I think the idea behind rev-matched shifts (of which double-clutching and
> heel & toe downshifting are two techniques--can be used together if you can
> chew gum, pat your head, rub your tummy, AND walk down the street all at
> once) is to 1) to lesses drivetrain shock (engine, clutch, tranny, final
> drive, etc) when releasing the clutch on a downshift in preparation for a
> corner and 2) to lessen tendencies to imbalance the chassis when at
> threshhold braking (especially if you really goofed, and are already into the
> corner before you shift--oops).  

I had the delightful opportunity to spend lotsa $$ for two days 
at Mr. Bondurant's school some years ago - and although there are 
many motions involved, once you've got it, you don't lose it easily.  
Of course, since I drive a 280ZX, and the pedals are optimally placed 
for heel and toe shifts, regular review (just to keep in practice, of 
course...) seems to be indicated.  :-))))  My wife's Audi is "clutch 
challenged", meaning that it's a slushy.  :-((

Happy Friday, folks!!

********** A Washington State Cougar in Aggieland (aTm) **********

Al Powell                           Voice:  409/845-2807
Ag Communications                   Fax:    409/862-1202
107 Reed McDonald Bldg.             Email:  a-powell1@tamu.edu 
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"There are two kinds of truth.  There are real truths and made-up 
                    truths."   (Marion Berry)
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