Omaha daily bee., 1907-05-12
TIRES FOR THE AUTOMOBILE
vsstigation as to What is Proper SIS,
and Material for Safety.
INTERESTING TESTS ARE CARRIED CT
Standardization the Aim and the
Number Of sizes In Use is Reduced
by More Than Half as Result
OF Inquiry.

Tires and their Standardization, a prob
en- that has confronted the automobile
Industry from it's inception is to be the
ext big work Of the mechanical branch
the Association Of Licensed Automobile
Manufacturers. Tho. success Of the assoc
iation's screw standard. its standardized
park plug. its various experiments In
metals and oils and its many educational
ngine tests. will be followed by series
2 tire tests and adoption OF standards
which will be OF material advantage to
III motorists and manufacturers.
Tests show that the part of the tire
nearest the ground and what is known as
tread rubber. TO give the best results,
should be Of compound rubber. as pure
rubber would not stand the continuous
friction caused by coming in contact with
the road surface. Near the center Of the
Ire comes the breaker strip" made up
IF two or three layers Of canvas sep
aratlnE the tread from the next layer Of
rubber or cushion stock" The cushion
stock Is usually OF the highest class rub
Der, being only slightly compounded; the
next layer toward the center is a five or
5X-ply fabric frictioned inside and out
The degree Of compromising can be OBJ
tanned by the specific gravity OF the rub
Der, It being known that the specific gray
ity of pure rubber Is between $50 and $50
The ash. after burning the rubber at a
low degree of heat represents the degree
Of compromising Independent OF the sulphur
used for vulcanization. To determine the
strength. a strip of rubber is cut from
each Of the different layers Of qualities
In the tire. one-fourth inch wide and one
eighth inch thick one end is gripped and
Hsan.N
until the strip breaks. Para rubber
shows high strength and the cheap rubber
low strength. In determining the elias
ITCHY a similar strip is cut from the tires
one-fourth inch by one-eighth inch and a
measured length of ten centimeters is
taken. The strip is then stretched be-
tween nails on a board until the ten cent?
meters length becomes thirty centlmeters.
II is kept in this position for twenty-four
hours, then released. and ten minutes after
release the permanent set taken. A good
rubber has small permanent set; poor and
cheap rubber has much permanent set.
Relative Site of Tires.
Considerable discussion has been given
| 20 the relative merits Of different size tires
on front and rear wheels. The size Of tires,
of course, depends on the weight of car
| and its gearing. Many manufacturers have
! found It to advantage to use a smaller
| diameter tire on the front wheels than on
the rear, and careful investigation seems
to prove this to be wise. First, it is much
| easier to steer, 1t having a smaller friction
area on the ground surface, this makes the
| wear on the tire, as the whole. considerable
] less, with chances for puncture decreased.
| 1t has less weight In itself and is nearer
| proportion to the weight of the car which
| Is, OF course heavier in the rear For high
powered cars, that is, cars required TO at
tain a speed Of from forty to sixty miles
an hour the smaller the diameter of the
| front tire. the less the danger In case of
blow out or puncture s. F. Edge, a noted
English driver, has made several tests to
/ dtermine the relative shock caused by
punctures, of different size front tires with
the result that with three or three and
one-half inch tire. a car going fifty miles an
! hour would be thrown over six or eight feet,
I while with an explosion OF a fve-inch tire,
II would be thrown from thirty to forty
feet. Economy and safety call for a
smaller diameter front tire. Many do not
think It an economy to carry two size
tires, but in the long run. It will be found
more advantageous. For racing purposes
a French driver will not use over ninety
mimmeter tire on the front wheels
One Of the first recommendation Of the
tire committee Of the mechanical branch
was the elimination of so many sizes of
tires that is, the wheel sizes. Up to the
time the mechanical branch took hold OF
this matter, there were twenty-three sizes
OF tires in the market, many Of which were
incapable of doing the maximum amount OF
work required, owing to their being OF
wrong proportion, not only for the weight
of the car. but the area of the ground sur
face. Experiments by the branch have re-
suited in a reduction of this number and
the adoption of eleven sizes.
/ Uniformity In Rims and FelIy.
A great difficulty that has confronted
the automobile manufacturers IS the vari-
GUS sizes of rims on the market. thus
causing considerable rim cutting to tires
Many Of the rim makers of single piece
rims had a uniform size diameter and
depth Of clinch, but not all. Through the
efforts of the branch the rim makers have
all agreed to a standard size rim to be in
spected and passed by the tire makers who
will guarantee any tire bearing the rim
associations STAMP
Tests and experiments are being made
for the Standardization of quick detach-
able tires and demountable rims, results
OF which when completed will prove OF
considerable advantage to all tire users.
| TO utUnnnlldNt tiit lAASNNobAAiNg "a 1850
, theories and in order that the progress
made during the year in perfecting the
, automobile may be seen. the members Of
the Mechanical branch OF the Association
OF Licensed Automobile Manufacturer
will hold a two days session In Hartford
, the early part OF May. On May the regu
r lar monthly meeting will be held at tn
, laboratory The principal subjects TO b.
discussed win be fabrication and coOlinl
systems. The salient points Of the splash
gravity OF force feed systems will be takei
. up ana the merits Of internal or externa
r oil leads given consideration. The dis
Z oussion Of water versus air-cooled motor
3 which will undoubtedly develop some in
teresting data Under the first. points 70
deliberation are types and makes OF radi
= etors pumps. the capacity Of pumps. pip
. me alter inlet and outlet and their sizes
B For the air-eooied motor, fapges and fan
will be reviewed.
9 T-be second days meeting will be give
over 20 A demonstration OF some OF Tn
work accomplished by the branch durin
e the past year. II Is expected that cars o
All members Of the licensed Association
U,ul he on hand ard tried out under III
7 S,ro.tton 81 the test committee for IN