Omaha daily bee. (Omaha [Neb.]) 187?-1922, 1907-05-05
TIRES FOR THE AUTOROBlLE
Investigation a. to What is Proper s'ss
and Material ior saiety.
NTLRLsTNe ISIS ARE cARRItO ON
Decentralization the Aim and the
Number Of sire- In Use = Reduced
BY more Than HsIf ss Result
Of Inquiry.


Tires and their Standardization prob
lem that has confronted the automobile
industry from it's inception. n to be the
next big work Of the mechanical branch
Of the Association OF Licensed Automobile
Manufactures The success OF the asso-
Citations screw standard. its standardized
spark plug It's various experiments In
metals and oils and its many educational
engine tests. viii be followed by q series
Of tire tests and adoption OF standards
which win be Of material advantage to
all motorists and manufacturers.
Tests show that the part Of the tire
nearest the ground and whnt Il known rs
tread rubber. 10 give 1.-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
tire comes the breaker strip made up
OF two or three layers Of canvas, sep
aratinR the tread from the next layer Of
rubber OF cushion stock" The cushion
stock Is usually Of the highest class rub
Der. being only slightly compounded; the
next layer toward the center is five or
six-ply fabric, frictioned inside and out.
The degree Of compromising can be OBJ
tanned by the specific gravity OF the rub
Der. II 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 grlpped and
weights are then added to the other end
until the strip breaks. Para rubber
shows high strength and the cheap rubber
low strength. In determining the elias
ITCHY similar strip is cut from the tires
one-fourth inch by one-eighth inch and a
measured length of ten centlmeters is
taken. The strip is then stretched be.
tween nails on board until the ten cent?
meters length becomes thirty centimeters.
II Is kept I'm 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
to the relative merits of different size tires
on front and rear wheels. The size Of tires
OF course, depends on the weight of a car
and it's gearing. Many manufacturers have
found II 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. 1t is much
! easier to steer, it having smaller friction
area on the ground surface, this makes the
wear on the tire. as the whole. considerable
less, with chances for punctuTe decreased
1t has less weight in itself and is nearer
proportion to the weight OF the car, which
| 10 nj han xylo tn he Tor hfuf
powered cars, that is. cars required to at
tain 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 noted
English driver, has. made several tests &c
| dtermine the relative shock caused by
punctures, of different size front tires witt
| the result that with three or three and
/ one-half inch tire, car going fifty miles ar
| hour would be thrown over six or eight feet
| while with an explosion of a hve-inch tire
| II would be thrown from thirty to forty
| feet. Economy and safety call for q
smaller diameter front tire. Many do moi
think 1t 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 this
] tire committee Of the mechanical branch
was the elimination of so many sizes o.
tires that is. the wheel sizes Up to the
time the mechanical branch took hold o.
this matter there were twenty-three sizeI
OF tires In the market, many Of which wer'
incapable of doing the maximum amount 3
| work required owing to their being o
/ wrong proportion, not only for the weigh
1 Of the car. but the area of the ground sur
face Experiments by the branch have re
suited In a reduction Of this number ans
i the adoption OF eleven sizes.