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on the road
Air Pressure
The most important factor in maximizing the
life of your tires is maintaining proper inflation.
Driving on a tire that does not have the correct
inflation pressure for the load of the vehicle is
dangerous and may cause premature wear, tire
damage, and/or loss of control of the vehicle .
A tire that is underinflated will build up exces-
sive heat that may go beyond the prescribed
limits of endurance of the rubber and the radial
cords . This could result in sudden tire failure . A
tire that is underinflated could also cause poor
vehicle handling, rapid and/or irregular tire
wear, or an increase in rolling resistance which
results in a decrease in its fuel economy .
Over inflation will reduce the tire's footprint or
contact patch with the road, thus reducing the
traction, braking capacity, and handling of the
vehicle. A tire that is overinflated for the load
that it is carrying will also contribute to a harsh
ride, uneven tire wear, and will be more suscep-
tible to impact damage due to overloading .
Maintaining correct tire inflation pressure for
each loaded wheel position on your vehicle is
of the utmost importance and must be a part of
regular vehicle maintenance .
Federal law requires that the tire's maximum
load rating be molded into the sidewall of the
tire . If you look on your tire's sidewall you'll
see the maximum load allowed for the size tire
and load rating, and the minimum cold air infla-
tion pressure needed to carry that stated maxi-
mum load . Utilizing less air pressure means a
lesser load can be carried by the tire .
The amount of air pressure you need to use
depends on the weight of your fully-loaded vehicle .
So, you cannot determine your correct air pressure
unless you know your vehicle's actual weights .
Under inflation
When an under inflated tire is run at normal
highway speeds, it flexes too much and builds
05-10
up heat . This heat damages the inner liner, cas-
ing and outer sidewall of the tire . If not remedied
quickly, the tire will be irreparably damaged .
In extreme cases, the sidewall of the tire is
destroyed, both from the excessive heat it endured
due to the weight of the vehicle pressing on the
tire casing without the cushioning load carrying
effect of the correct air pressure, and the crushing/
cutting action of the wheel as it rolls on the under
inflated sidewall. According to guidelines put out
by the Rubber Manufacturers Association (RMA),
any tire that has been run at less than 80% of rec-
ommended air pressure for the load it is carrying
should be inspected for possible damage .
When one tire in a dual configuration comes out
of service due to under inflation damage, the
other tire in the dual configuration should be
inspected immediately . If the unserviceable tire
was under inflated, that means the serviceable
tire was carrying more and more of the load for
that wheel position . Consequently, it too may
have suffered some casing damage due to over-
loading .
Air Pressure Check
You should check the air pressure every two
weeks or at least once each month and before any
major trip . Your RV tires' air pressure should be
checked every "drive" morning on long trips . On
short trips of a day or less driving each way, your
tires should be checked before you leave on your
trip and again before you start your trip home .
Check your tires when they are "cold" and have
not been driven for more than one mile . The
stated load capacity for a given cold inflation
pressure is based on ambient outside tempera-
ture . If you must check your tires when they are
warm or hot, do allow for a slight increase in air
pressure and make sure they are within a couple
of pounds of each other on the same axle .
Frequently check tires . If a tire picks up a nail or
screw that creates a slow leak and causes some
air pressure loss, you might eventually spot it
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