The Washington herald., 1913-10-19
INITIATION and
TIRE TROUBLES
Points Of Interest to Motor
Car Owners Discussed
by Expert.
SIZE OF THE AIR CUSHION

things of which one is as important as
the other. One of these is an air cusn-
ION. the other is an envelope for retain
ing air under pressure and making this
air cushion possible. This envelope Is
spoken Of by the trade as the tire, and.
as every motorist knows, consists of
casing and an inner tube, the casing to
resist road wear and the tube to furnish
an air-tight inclosure for the air in
side. The casing is made of rubber and
fabric and the tube of rubber. This mass
OF rubber and fabric construction VIII
not sustain the weight Of any car; it
Is the air cushion il retains that sup
ports the cars weight.
Naturally, a larger car will require
more of an air cushion than a smaller,
and, in the same way, larger tire to
carry this larger air cushion. A car OF
given weight requires a tire OF given
size containing air under a given pres
sure.
Let us consider the result when the
tire does not contain proper air pres
sure 1t already has been pointed out
that the tire itself cannot sustain weight.
but that this is-the purpose of the air
cushion inside. But when this air cushion
consists of air under insufficient pres
sure. the tire is forced to sustain part
Of the weight itself, exactly in proper
tion to the deficiency in the air pressure
something it is not built TO do.
Tire FIattened Out.
The first result is that the weight
above, being no longer properly sus-
tained. fiattens the tire out where 1t
rests on the ground. Then, when the
car is put in motion, every part of the
tire on reaching the bottom must as
sumo this unnatural fiattened shape.
Each side must bend out and then oack
again at every revolution.
The body OF the casing consists OF
several plies of fabric united as whole
by the rubber which has been vulcanized
through and through And when the side
walls bend in and out because Of under
inflated condition, these fabrics layers
do not unite their strength and act as
a unit, as they are meant to, but the
unnatural bending makes one layer pull
against the one next to it. They fail TO
reinforce each other as they should.
Continually pulling against each other,
these fabric layers in time pull apart,
separating from each other. The same
conditions which caused them TO pull
against each other now causes them to
rub and chafe. This produces friction
and heat. The different layers soon wear
each other out, and so soon as some one
place becomes too weak TO sustain the
inside air pressure. the tire gives way
with a blowout"
The tire manufacturer tries to make
perfect casings and tubes. A perfect
casing and tube is one of the factors of
good tire service. The other factor is
correct air pressure, and this is up TO
the motOrist
Several Kinds of Abuse.
There are several kinds OF tire abuse.
but as proper imitation is so vitality i'm
portant, insufficient imitation is more
damaging than anything else. The
statistics compiled by' all the leading tire
manufacturers indicate that more than IS
per cent of tires that have gone out of
service prematurely did so because OF
insufficient imitation.
There are several indications of under
imitation. The most common one is the
condition of the inside fabric. Under
imitation separates the fabric layers and
this separation shows itself by means of
4 ridge or roll of fabric on the lower
part of the side wall on the inside of
the casing. This is before the tire is
ready to give way completely. After a
tire with separated fabric is run a while
and then- removed it will be found that
the fabric at the place it was rolled up
into a ridge before is now cracking and
Beginning 10 break. In this condition it
is soon ready to give way.
Another condition is the loosening at
the tread. differentiation produces a
little roll right in front of the point of
contact with the ground. which in time
tends TO separate the tread.
In the case of clincher tire, under
imitation usually permits the tire to be
rim-cut before the fabric gives way of
itself. Bending in and out increases the
normal action of the hook of the rim
against the cIincher bead of the tire.
The Right Prex.ure
II viii be interesting to know how to
determine the right pressure. Use twenty
pounds for every inch of width. For ex-
ample, use sixty pounds in tire three
inches wide seventy pounds in a three
and one-half-inch tire, eighty pounds in
four-inch tire, &c.
AS under-infation is such a universal
cause of trouble, it develops that the
reason the average motorist does not
give the air pressure in his tires the
attention he should is because he does
not realize its Importance
In addition to pointing out the danger
Of under-infiation it is necessary to show
how to guard against it. There are two
precautions the motorist can take which
will do this; one is to initiate the tire
properly at first, and the other is to
add 10 the tire every few days enough
air to balance what has been lost in the
mSdnume. NO lre Is aDSOlutely air
tight. so it should be inflated every few
days. To be sure about the proper pres
sure the motorist should use a pres
sure gauge. number of reliable and
Inexpensive gauges are on the market,
which will pay for themselves several
times in reducing tire exepnse.
To summarize then. an analysis of
the causes OF deficient tire service by the |
leading tire manufacturers shows that in
over 75 per cent of the cases under-in- |
hatfon is responsible. Under-infiation |
ruin can be avoided by observing the fol- |
lowing rule. Cut this out and carry it |
in your pocket or paste it up in your
garage:
KEEP TIRES INFLATED ACCORDING TO
THE FOLLOWING: