Re: <ALL> Another method to determine tire pressure?

[Brian M Kennedy <kennedy@xxxxxx>]

James Donohoe wrote:

> What's the best way to determine optimum tire pressure on a bike? When we
> Auto-X, a container of white liquid shoe for window numbers is what we
> usually squirt on the edges of the tires to see how far we are rubbing and
> increase/decrease pressure as necessary. Since you can't do that on a bike,
> what DO you do? His solution was to set the pressure per manufacturer's
> specs, take it out and ride hard, immediately stop and check pressure. It
> should go up 10% from where you set it. If it goes up less than 10%, your
> pressure is too high and greater than 10%, your pressure is too low. The
> heat is generated by the tire rubbing against the rim so if the pressure is
> too low then your tire is sliding all over the rim.
> 
> My question to the digest is: Can this be applied to our cars? Or at least
> something similar? It seems like a very elegant and much more precise method
> than liquid shoe polish.

My response:  Why 10%?  What's magic about 10%?  (IOW, that technique
sounds pretty questionable to me -- I think you are more measuring how
much water is in each of your tires.)

In contrast, what's magic about rubbing off shoe polish?  Well, obviously,
it's bad if your tire rolls over onto its side.  Its weakness is that you
don't want it even close to rolling onto its side -and- it is fairly 
weak at determining if your pressure is too high.

For a more precise way of adjusting pressures, measure tire temperatures
inside, middle, and outside on all four tires right after a run.  Try to adjust
pressures such that the temps are all fairly even (you won't get them equal; 
just as even as possible).  If the middle is hotter than the edges, lower the
pressure.  If the fronts are hotter than the rears, adjust pressures to 
compensate.  And vice versa.
(Not only does this adjust pressures for the good of the tires,
it also helps bring your car closer to neutral handling.)


Brian

P.S.  Where's the best place to buy a pyrometer (or a tire temperature
guage)?

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