The evening times. [volume] (Grand Forks, N.D.) 1906-1914, 1913-02-20

hard" On the other hand. a tire
containing only a small amount Of air
pressure will be exceedingly suscepti-
Die to depression of its tread when an
OBSTACLE is encountered, and the rub
per at the point of contact may be
ilattened almost to the rim. Thus a
hard tire is enabled to encounter a
great many abrupt inequalities in the
road, but will not absorb slight shocks
ana Jars. while a soft tire is sensitive
10 even the slightest obstacle in the
suggestion of trough going"
1t is evident that a tire Containing
too much air will make the roads
seem rough while one that is too
on good roads but distressing on rough
surfaces where the cushioning ia in
sufficient. But it is a strange paradox
that a hard tire will last longer
tnan a soft tire. In the latter case
n casing and tread are depressed at
II slightest obstruction. 4 gradual
weakening of the tissue results. A
tire containing the full amount of air
pressure on the other hand is moi as
migrating wear and tear from
spreading is not SO violent. The aver.
susceptible to the bumps and the dis.
age pressure favored by tire manu-
1acturers is about twenty pounds per
SQUARE inch for each inch Of diameter
OF cross section Of tire. For example
a four-inch tire should be pumped to
an approximate pressure of eight
pounds to the square inch. while ona
an inch larger should carry 100
pounds of pressure.
1t is a simple matter to test the tire
pressure by the use of one of the
many pressure gauges now on the
market. 1t such Il gauge is not car
rled IN the kit. rs it should be-. an.
pfoAlinate pressure in the cars ma be
gagged by the contour of the tires as
they carry the car at it's weight fully
loaded. AS soon as the tire is pumped
to the limit where the weight of the
car does not change the perfectly
round appearance Of the outside cir
Icunl1erencc or as soon as the tire does
not natten at h point of contact to
inc road or floor 1t is properly filled.
If the side walls bulge at the point of
contact. however, nor air should be
pumped into the tire.
Manufacturer Not to Blame.
Tires. have been credited with going
to pieces mysteriously and the limo.
cent manufacturer has been criticized
because of a bad fabric. One of tht
so-caIled mysterious causes Of decay
is the improper alignment of wheels,
winch causes uneve Wear on the
shoes. This evil may not be apparent
at casual observation. but in MANI
cases it exists unbeknown to the driver
or tire dealer. Both may be up in the
ar over Il simple fault. This may be
detected by the application of a long
rule to the tops and bottoms of the
front and rear wheels. If the two
wheels Of a pair do no revolye in
planes parallel to each other in a hori.
zontal position they are out of line and
the tread of the tire will tear as we'll
as rub e the even surface in much
the same anner as it the wheel we're
pulled slightly sideways at every revo.
luton. The measurements should be
taken at points exactly opposite on
the front of and at the rear of the
wheel hubs. If the distance between
the two wheels is less at the rear than
it is forward of the hub it is evident
lthat the aXles or spindles arc SD bent
That the wheels do not revolve in par-
allcl planes and the car should be TAX
len to the repair shop immediately.