Evening journal., 1913-10-21
Says Largest Per Cent of Tire
Trouble Due TO UnderinfIafi0n
By =. 4. HENDERSON,

o.
A pneumatic tire consists of two
things. OF which one is as important
as the other One Of these is All air
cushion, the other is an envelope for
retaining air under pressure anu max
ing this air cushion possible. This
envelope is spoken of by the trade as
he tire and as every motOrist knows,
consists of a casing and an inner
tube: the casing 10 resist road wear
and the tube 10 furnish an alright
inclosure for the air inside. The cas-
ing is made Of rubber andfabric, and
the tube OF rubber. This mass OF rub
CT aud fabric construction will not
sustain tho weight Of the car; it's the
air cushion IT retains, that supports
the weight OF the car
Naturally larger car will require
moro of an air cushion than a smaller
aud IN the same way. q larger tire
TO carry this larger air cushion.
car Of given weight requires tire
OF a given size containing air under
given pressure.
Let us consider the re- suit when the
tire does not contain the proper air
pressure. II has already been point
ed on that the tire itself cant sustain
weight but that this is the purpose Jf
the airc ushion inside But when tails
air cushion consists of air under m
sufficient pressure. the tire is forced
TO sustain part of tho weight itself,
in the AR pressure. sOmeCllng It Is
exactly in proportion 10 the dciicicn,s
not built to do.
The first result is that the weight
above being no longer properly sus
rt.1..
rests on the ground. Then, When tie
car is put in motion, every part OF
the tire on reaching the bottom, mus,
assume this unnatural nattencd shape.
Each side must bend out aud then
back again at every revolution.
Tho body Of the casing consists OF
several plies of fabric united as
whole by the rubber which has been
vulcanizcd through and through. Aud
when the side walls bend in and out
because Of under inflated condition
these fabric layers do not unite their
strength and act as q unit as they
are meant to. but The unnatural bend
ing makes one layer pull against tho
ono next 10 il. They fail to reinforce
each ether 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
cause them to rub and chafo. This
produces friction and heat The dit
ferent layers soon wear each othcr
out, and so soon as some one place
becomes too weak to sustain the in
side air pressure the tire gives way
With blowout
Tho tire manufacturer tries to make
perfect castings and tubes. A per
feet casing and tube is one Of the
factors OF good tire service. The other
factor Is correct air pressure and this
is up 20 the motorist.
Tho.s arc several kinds Of tire
abuse. but as proper Imitation IS SO
1itally important insufficient inha
ton is more damaging than anythins
clso.- Tho statistics compiled by al
the leading tire manufacturers. ind
cate that moro than 55 per cent. o
tires that have conc out OF SERVED
prematurely. did 50 because or insut
fcicnt insulation.
There arc several indications If un
derinfation The most common on,
is the condition OF the inside fabric
determination solf by means Of 3
iidge or roll OF fabric on the iowci
part of the side wall on the inside
Of the casing. This is before the tir,
is reaoy to give way completely. AT
ter 4 tire with separated fabric is ruf
while and then removed. il viii h'
found that the fabric az the place 4
was rolled up into ridge before, il
nov uackine and beginning TO break
I'm this condition il IS soon ready t'
give way.
Another condition is the loOsnnini
NJ the tread. determination produce
little roll right i'm front Of tho poin
and in time tends to separate IN
tread.
In case OF a clnchcr tire. upderir
fation usually permits the tire to h
rim-cut before tho fabric gives wa
Of itself. Bending IN and out increase
The normal action OF the hook of th
rim against the clincher head Of tn
tire.
1t will be Interesting to know HOY
to determine the right pressure. Us
20 pounds for every inch OF widtl
For example. use so pounds in Z
tire 9 inches wide. 20 pounds IN a
IL inch tire, 80 pounds in 4 incl
tire. etc.
As underinhation is such a univeI
sal cause OF trouble, il develops tina
the reason the average motorisf doc
not give tho air pressure in his tire
the attention he should. is hecaus
he docs not realize its importance
In addition TO pointing out the das
gor OF undorinlation it is necessar
10 .how how TO guard against
Phc are two precautions the motO
ist can take which will do this; on
is 10 initiate the tire properly ~ iiri
and the other Is to add 10 the tis
every few days enough air TO halaus
what has been lost in the meoniim
~ tire is absolutely airtigh; so
should he inflated every few DAYS 7
he sure about the proper prcssur
the motorist should use a pressr'
Rsuge. a number of reliable and il
expensive gauges arc ON the mark
which will pgy tor themselves sever
Vines IN reducing tire eXpeuse.
To summarize thcn. an analysis
the causes OF deficient tire service 7
The leading tire manufacturers, show
that in over 80 per cent. of the case
rndcrinhation is Responsible lnde
fphation ruin can he avoided by O
serving the following rule, Cut IN
cut and carry il In your pocket
paste II ~ in your garage
Keen tires inflated according 70 q
following;
re inch ................. 80 II
lHct .''s's-. ..bV II
81. lnfn ............ ...ft IN