Kevin Anderson wrote:
I don't think they run cooler, but I know that using nitrogen the pressure
stays more consistant as the tire heat up

Do you guys stay up late making this stuff up or do you really, honestly
believe that?

Have you ever heard of - much less read - the "gas laws'? Look up a
French chap named Charles and Gay-Lussac and their particular
contribution to the art.

Exactly how do you "know that using nitrogen the pressure stays more
consistant (sic) as the tire heats up"?

The reason nitrogen is used in high performance tires (usually aircraft)
is that it will not support combustion or oxidation of rubber compounds
in a very high temperature application. Compressed nitrogen is normally
dry, very low in moisture content as well as completely free of oil
which is a contaminant delivered by many air compressors. All the normal
gas laws still apply.

The only thing worse than the general lack of basic scientific knowledge
shown here is the willingness of people to post that they "know" that
the laws of physics simply don't apply.


Rick

"Rick" wrote in message
ink.net...
Kevin Anderson wrote:
I don't think they run cooler, but I know that using nitrogen the
pressure
stays more consistant as the tire heat up

Do you guys stay up late making this stuff up or do you really, honestly
believe that?

Have you ever heard of - much less read - the "gas laws'? Look up a
French chap named Charles and Gay-Lussac and their particular
contribution to the art.

Exactly how do you "know that using nitrogen the pressure stays more
consistant (sic) as the tire heats up"?

The reason nitrogen is used in high performance tires (usually aircraft)
is that it will not support combustion or oxidation of rubber compounds
in a very high temperature application. Compressed nitrogen is normally
dry, very low in moisture content as well as completely free of oil
which is a contaminant delivered by many air compressors. All the normal
gas laws still apply.

The only thing worse than the general lack of basic scientific knowledge
shown here is the willingness of people to post that they "know" that
the laws of physics simply don't apply.


Rick

Um, Rick,

Race car operators take a great deal of time and effort to first dry their
tires, then fill them with dry nitrogen. The reason is that the water in the
air does NOT act like an ideal gas. Think about what happens to the
pressure/volume curves as the tire reaches 100 degrees C.

http://www.porschenet.com/bruns04.html

There are other perceived benefits that may induce an operator to switch to
nitrogen.
I am not ready to support this other stuff, but throw it in just to cover
the subject more fully.

http://www.branick.com/n2/faq.html

Mark Browne

Mark Browne wrote:

Um, Rick,

Race car operators take a great deal of time and effort to first dry their
tires, then fill them with dry nitrogen. The reason is that the water in the
air does NOT act like an ideal gas.

yeah, and did you notice that I wrote:

Compressed nitrogen is normally
dry, very low in moisture content ...

Rick

"Rick" wrote in message
ink.net...
Mark Browne wrote:

Um, Rick,

Race car operators take a great deal of time and effort to first dry
their
tires, then fill them with dry nitrogen. The reason is that the water in
the
air does NOT act like an ideal gas.

yeah, and did you notice that I wrote:

Compressed nitrogen is normally
dry, very low in moisture content ...

Rick

Yes, but now the others on this group have a better understanding of the
factors involved.

Mark Browne

Mark Browne wrote:

Yes, but now the others on this group have a better understanding of the
factors involved.

I am not going to bother to run the numbers but the partial pressure of
any "normal" quantity of water vapor in a tire is not going to change
the tire pressure by an amount easily measured by anyone outside a
laboratory. It will have no significant influence.

Moisture will however contribute to corrosion and oxidation at elevated
temperatures in an oxygen bearing atmosphere. How much of a factor this
is in an application where tires are changed every few minutes anyway is
debatable.

I think your racer/writer/engineer friend might be disappointed when he
fails to see much, if any, measurable difference in his tire pressure.

Rick

Joe Here wrote in message . ..
This past Summer, took our 15 foot fiberglass on a long road trip
instead in the usual half mile to the marina. The tires are the small
4.80-8 utiltiy type tires, and needless to say, they overheated
badly.....
long story, but I'll be upgrading to a biger tire this Summer.

Here's my question. It seemed that the speed at which the load was
being carried created the heat. While pondering the trip home
(semi desperate and after a few beers) I considered filling the tires
with water (say 50%) in an attempt to dissipate the heat to the rims.

I never did this, but have pondered the the effects of water in a tire
at speed. Would the balance go for a bundle or would the water be
thrown evenly within the tire by the certifugal force?

I made the trip home by upping the pressure to 60 p.s.i. and by
driving slower.

Would water have helped of would I have been courting a disaster?

No, water would have just added to the mass. I have a boat with 8"
tires. I had 4.80-8's on it, told the guy at the tire shop that I
thought they got too hot, he put on 5.70-8's on, problem solved. You
can use the same wheels. They stay MUCH cooler. If you look, after
mounting one and blowing it up, and compare it to the 4.80, you'll see
a difference in heighth as well as width. It doesn't make as many
turns per mile as the smaller tire! The load range is greater, the
recommended tire pressure greater, and the contact patch greater.
Trust me, been there, done that.

(Wwj2110) wrote in message
nitrogen helps tires run cooler

Only because when nitrogen is used instead of air, the pressure to
temperature ratio is more linear. The nitrogen doesn't run any cooler
than with air.

basskisser wrote:

nitrogen helps tires run cooler


Only because when nitrogen is used instead of air, the pressure to
temperature ratio is more linear.

You really ought to stop kissing fish, it has diminished your powers of
reason.

rick

"Mark Browne" wrote in message
news:8H_mb.39146


The reason is that the water in the
air does NOT act like an ideal gas.

Gosh, I didn't realize that there had been a change in the laws of physics
since I went to college! When did this happen?

Man, things were easier back in my day when any gas obeyed the gas laws!
Remember when the steam tables were what you would use for any gas you
didn't know the properties of?

Think about what happens to the
pressure/volume curves as the tire reaches 100 degrees C.


The vapor pressure for water will vary over a very large temperature range.
Fortunately, it is predicatable and monotonic. If you didn't have liquid
water in the tires when they were cold, you won't have any liquid in them as
they heat up.

I can see reasons that a race car might want to use nitrogen in their tires.
It is a nice, safe gas. It is realatively cheap. The fact that it is
readily available in a very dry state can have its advantages: I can imagin
that avoiding any condesation when the tire was cold could be an issue,
especially during the winter. The issue would be maintaining a
"predictable" inflation pressure as the tires went from "colder than when
they were inflated" to nominal operating temperatures. I suppose that
condensation could also be an issue when the wheels were balanced.

Rod

"Joe Here" wrote in message
...

Here's my question. It seemed that the speed at which the load was
being carried created the heat.

It is the flexing of the sidewalls that creates most of the heat. The more
they flex, and the faster they flex, the more heat is generated.

A taller tire rotates slower, thus a given spot will flex less often, thus
it won't get as hot.

A stiffer tire won't flex as much. A tire with a higher load rating will be
stiffer. Tires are stiffer when properly inflated. Thus, a tire that is
not overloaded and is properly inflated shouldn't overheat.

While pondering the trip home
(semi desperate and after a few beers) I considered filling the tires
with water (say 50%) in an attempt to dissipate the heat to the rims.

As others have said, NO!
If nothing else, this will cause a major imbalance in the tire.

Rod