Hi.

"Keep in mind that OVERINFLATION of your tires will actually HURT your
gas milage. The reason for this is because it changes the "footprint"
of the tire on the road, or the amount of tire you have in contact
with the road. Overinflating tires lessens how much tire is on the
road and contributes to slip. The more slip you have, the worse milage
you will get."

And

"So if you overinflate your tires, especially on the rear of a truck,
then you have increased the amount of slip exponentially."

These are your statements that I'm having trouble with. The first
statement I believe is false. If you want to say that overinflation
(and we still haven't said by how many psi) will cause poor handling
or poor tire wear or less effective braking, then fine. But you are
saying that it will hurt your gas milage, and I've not seen you
produce any evidence that corroborate that statement as fact. As a
matter of fact, the first link you sent sorta hurts your argument.

The second statement: While I'm very well versed in how to search the
web, I was fairly certain it would be hard to find the same research
you were using to cite those exponentially numbers.  That's why I
asked you for it/them.

Remember, I'm only speaking to the issue of overinflated tires and
their effect on milage. You say it has a negative effect, ON MILAGE,
I say it doesn't.

Here's just a bit of stuff I found, one of them from you:

"Method: We drove the 55-mile test loop four times at 60 mph — twice
with tires at or above proper inflation. Once, we did the test with
the tires 5 psi below the pressure recommended by the manufacturer.
Since this produced very little difference we enlarged the gap and
under inflated the tires by 8 psi. We felt that it was important to
make sure the tires were inflated to the recommended level or above."
This from the link you sent.

http://money.cnn.edmunds.com/ownership/driving/articles/106842/article.html#test5

------------

"Good inflation: Drivers waste millions of gallons of fuel each year
due to under-inflated tires. Maintaining optimum tire inflation is one
of the best things you can do to increase fuel economy. Inflate your
tires to the upper limit of the manufacturer's recommendations."
http://www.autosite.com/content/research/index.cfm/action/showarticle/AID/135657
------------------
"Harder tires present less rolling resistance and improve gas mileage;
therefore, the Buick Estate Wagon outperformed our expectations based
on our regression model, which did not account for tire inflation
pressure. In our model Tire Pressure is a lurking variable, variable
that seems to help in predicting gas mileage but is not included in
the model."
http://score.kings.k12.ca.us/lessons/wwwstats/lurking.variables.html
-------------

"and keeping tires inflated to the maximum recommended pressure can
improve your gas mileage."

http://www.epa.gov/otaq/consumer/17-tips.pdf
---------------------

Me again.

I think you would be hard pressed to find anyone in an "official"
position suggesting that one "overinflate" one's tires past the
recommended maximum (due to liability), but they sure do seem to
suggest that you keep it as close as possible. But one wonders,
considering "Under-inflated tires can lower gas mileage by 0.4 percent
for every 1 psi drop in pressure of all four tires. Properly inflated
tires are safer and last longer." what every increase in psi (over the
recommended max) would bring?

Any way, I'm done with this discussion. Unless you can produce
evidence that shows  moderately over inflated tires decrease gas
milage, we'll just have to agree to disagree.

Have fun with the Head Gasket :)

Don

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