Checking Tire
Pressure - Determine Correct Pressure
How to figure the
correct tire pressure for larger tires.
This
article was spawned from a continuing
conversation from our Jeeping friend
Bob in his
quest to get his JK handling just
right.
If your Jeep is in stock form with stock size
and type tires you may not need bother with this
article. The recommended pressures listed
in the door jamb will suit you fine. But,
if you are like most of us your Jeep is lifted
and equipped with larger and probably wider
tires.
Typically larger tires handle your vehicles
weight differently than stock and the original
door recommendations don't necessarily apply.
Why should you care? A tire not properly
inflated will wear incorrectly and quicker than
a properly inflated one would. Replacing
tires that are worn out too quickly will hurt
you in the pocket book, in actually more ways
than one.
An
under-inflated tire will cause increased rolling
resistance which will rob you of fuel economy
and possibly damage the tire due to excessive
heat. Other symptoms of under-inflation
can be a steering pull.
On
the other hand an over-inflated tire can give
you an improvement in fuel economy but that
savings will disappear when you need to replace
your tires sooner. Over-inflation will
also cause a harsher ride potential poor
handling since the tires may skid over the road
instead of grip.
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Choose wisely.
Wheel Terminology
Terms and Metric sizes defined
|
tech
The right
illustration is a cross section giving a better
view to what proper or improper inflation does.
Under-inflated: Wears the edges of the tread
more than the center.
Over-inflated: Wears the center of the
tread more than the edges.
Proper: The entire tread is worn at the
same rate (aka, correct pressure).
What to
do?
Checking proper tire inflation is rather simple
and requires some chalk or a utility crayon.
Make
a mark all the way across each tire.
Drive the Jeep for a short distance, a straight
line is best.
Note
the wear pattern in the chalk. If there is
chalk left at the edge the tire is over
inflated. Chalk left in the center means
it's under-inflated. A clean pattern
indicates the pressure is just right. Make
a note of the pressure for future reference.
This procedure would need to be performed again
of different size or style tires are added.
Chalk Line |
Over Inflated |
Proper Inflation
Tire Size to Ratio
Conversion Chart
Figure out what RPM you will run with
those new mud tires.
|