The Washington times., 1925-07-08
BALLOON TIRES
GIVE N0RN|A[
TREAD WEAR
Royat Cords Designed To- Per-
sfsitsEow lnflation,Without
Losing Mileage

The engineering principles in:
VOWED fl the design and construc-
ton Of a pneumatic tire are those
involving stresses and strains. y
A pneumatic tire. is designed and
constructed! to deliver satisfactory
mileage when operated at a certain
DETECTION, which in popular terms
is ca1led Sf1attening at the point of
road contact.
Bp 60. the time of the develop
rnena of balloon tires, the applica:
tan or these engineering principles
inSefved only the, design and cor
struction Of a. tireE carcass which
would f1atten- under load to a
cefesfia1r extent End then Withstand
the ticking and bending in service
for assatisfac9ory mileage.
UOtA then the tread. the break
er strip the top cushion and side
walls. did not present any difficult
problem to the tire engineer and
the chemist. {, ".
But with the development; of the
baloorls tire. which was designed to
operate at lower initiation pressures
and with a greater flattening at the
point . OF T5ad eontacf. it soon, be-
came evident that ~the design OF
the tread was as. Important as that
of the carcass of the tire.
Treads designed along the lines
Of the high pressure tire wore very
rapidly on the shoulders and very
slowly in the center and other por-
lions.
The conventional round. tread ION
the balloon tire did not give the
tire the requisite lateral stability
TO prevent 3uh Gel gallop, Wobble,
and si1iFnfi5 One cure. for these
ilHS. WAS the substantial raising OF
the initiation pressure in. front tires.
but this was. Of course. only e
eomuronlise and It also uetracted
ollfte noticeabIv from the cushion
ing effect of the tires.
The engineers OF the United states
Rubber Company attacked the, proc
lem from the standpoint of preserv-
ing the original idea OF the balloon
tire. which was to give added COM
fort and riding qNalities through the
use OF low imitation pressures.
They set about Designing trea9
which would wear normally ana
slowly and which would promotS
ease of steering and give the car the
necessary lateral stability.
The result was tread contour
which, as compared with the orlgluaI
round tread, is wider and mucn
flatter.
thie tread give all the cushiontng
And comfort which a balloon tire is
intended to give, and At the same
fine the tread wear is perfectly
normal.
= This new tread. has been rightly
namad +hA ct S. Low-PresSure |
Tread'' because it has been spe-
c4fically designed to permit the low
inflations necessary to ideal balloon
without sacrificing mile
age.
tire is inflated. but not under load,
a nearly flat; but when under load
and working, it. ~ perfectly fiat so
that the entire- width of the tread
is in contact with the road.
This greater road contact dis
tributes the weight. evenly over the
tread surface and hence reduces the
weight on the individual trea i blocks.
This 1hewear and natural
" gives longer mileage than Is pos
sfble with a round tread.
In addition. il offers a number
Of other fundamentals, advantages,
namely, additional tractfve surface,
better non-skid protection, easier
steering and greater stability.
But the principal advantage is That
tires with thts> tread do not have
TO be overinflated to save them
from early, uneven and unsightly
tread wear, and, consequently ideal
cushioning pressures can be main
famed without sacrificing mileage.