Note: Descriptions are shown in the official language in which they were submitted.
7~
The present invention relates to a rim, a tire
and a combination thereof with improved capabilities when
the tire is run flat.
The run flat capability of an automobile tire,
particularly a passenger vehicle tire, has been investigated
for many years. Emphasis on the run flat capability of a
passenger car tire has increased in recent years due to the
desire by automobile manufacturers to eliminate the spare
tire in a passenger awtomobile.
This renewed emphasis on the run flat character-
istic of a pneumatic tire has resulted in many structures
designed to improve this characteristic. The goal of auto-
mobile manufacturers, and therefore tire manufacturers,
is to obtain a tire which will maintain automobile stabili-
ty and tire integrity after the vehicle is run as much as
50 miles at 50 miles per hour with the tire deflated (run
flat).
One line of teaching has been to include an insert
in the sidewall area of the tire to prevent the tire from
flexing or folding over upon itself when it is run flat.
Examples of this teaching are given in U.S~ patent
3,949,798, U.S. patent 3,954,131 and French publication no. -
2,257,444. Mone of the teachings identified above discloses
the concept of an asymmetric sldewall insert instruction
designed to offset the camber to which a tire is subjected
when it is run flat.
The use of an axially outward extending portion
on a rim flange has also been taught; see U.S. patent
2,367,825. This feature has been employed in recent tire-
rim combinations designed to have run flat capabilities;for example, see U.S. 3,935,327, English 1,359,463 and
English 1,390,024. Again, none of these teachings disclose
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a consideration of the angulation caused by the camber in
a vehicle tire when the tire is operated in a run flat con-
dition on the vehicle.
It is an object of this invention to provide an
lmprove~nt in ~ rlm, a tlra, anc1 a combln.ltion
thereof that results in the equal distribution of the ~ehicle
load on the tire when the tire is run ~lat. ~his eliminates
the uneven load that has occurred in the past with standard
tire and rim constructions or other tire and rim constructions
desi~ned specifically for run flat capabilities, as both of
these constructions did not take into account the camber to
which a tire is subjected when it is mounted on a vehicle
and is run flat. In a run flat situation, the uneven load
in the sidewalls (the load imbalance) is exaggerated and such
tires are more sensitive to this load imbalance. -`
In passenger vehicles the tire on the front positions
may be subjected to an initial camber of, on an average,
from approximately positive .5 to +2 and the rear tires to
an initial camber of approximately ~.5. This initial camber
setting is designed by the vehicle manufacturer for the best
compromise of all around vehicle performance with handling
being of ultimate importance and given the maximum consider-
ation. This initial, front position camber is accentuated
in the run flat configuration. It increases to angles up
to 4 and higher. The initial rear position camber also
increases on run flat operations.
A further object of this invention is to compen-
sate for this accentuated camber that occurs on front position
wheels, and on rear position wheels, during the run flat
operatlon of the tire.
A further object of this invention is to
improve the run flat capabilities of a tire or a tire and
rim combination by including features in the combination
which compensate for the camber imparted to the tire and
combination when the tire is run flat when it is mounted
on a vehicle either with or without an initial camber.
Rim, tire and combination thereo~ that lncorpo-
rates the features of this invention yield slgnlfiaant im-
provements in the run flat stability and durability of the
tire. Stability means that the tire will have a stable run
flat configuration so that the vehicle may be driven with
the tire in its run flat condition for several miles without
loss of control due to the run flat condition of the tire.
Durability means that the tire will survive the run flat
operation when it is carrying the vehicle load. This sur-
vival is manifest in that the tire will not be destroyed
during the run flat operation and therefore yield an un-
stable structure with the resulting danger of loss of control
of the vehicle during run flat operation.
The improvement of this invention is realized by
the structural features of this invention which ~esult in
an equal distribution of the vehicle load on both sidewalls
of the tire when the tire is operated in a flat condition.
Most front position passenger tires ~hen mounted on a ~ehi-
cle are mounted with a camber other than zero degrees. Camber
is an angulation of the tire in relation to the plane perpen-
dicu~ar to the road surface. It is common to have such angu-
lation on the order of positive 0.5 to 2 as measured from
this perpendicular with the angle inclined toward the ground
and toward the-center of the vehicle. Rear position tlres
may be mounted with a camber of about +0.5. This camber angu-
lation is necessary to vehicle geometry for all aroundperformanc~ under various driving circumstances.
As one looks at the front of the vehicle, this
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angulation results in what may be pictured as the -tires
being in a " pigeon-toed" relationship to the vehicle and
themselves; that ls, the tires will be angled so that the
portion of the tire that engages the road is closer to
the center of the vehicle than the portion thak is 180
away from the road engaging portion.
When a tire is run flat on a vehicl~, this camber
angulation is increased due to the uninflated nature of the
tire. This increase results in a camber of from approxi-
mately positive 2.5 to 4 in the front position whenmeasured in reference to a perpendicular to the road surface.
A positive camber is imparted to tires during run flat oper-
ation even though no initial camber exists.
This angulation of the tire during its operating
conditions, which is exaggerated during its run flat con-
dition, results in an unequel load in the sldewalls o~ the
tire. This has been demonstrated by tests which show higher running
temperatures in the sidewall on the outside side of the
tire and premature failure in this sidewall of the tire
as opposed to the sidewall on the inside ~vehicle side) of
the tire.
This disproportionate loading of the outside
sidewall of the tire is elimina,ted by a proper combination ''
of structural features in the tire itself and the rim upon
which the tire is mounted.
According to the present invention, there is ` ;
provided a rim for a pneumatic tire comprising an annular
drop center area having bead seats extending axially
outward from each lateral edge t~hereof, rim flanges located
axially outward of each said bead seat and rim flange ex-
tensions extending axially outward from each rim flange,
the improvement comprising said rim ~lange ! extension on
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the side of the rim designed to be mounted on the inside
of the vehicle forming a negative angle as measured from
a plane parallel to the axis of rotation of said rim and
the rim flange extention on the side of the rim desiyned
to be mounted on the outside of the vehicle ~orming a
positive angle to said plane whereby said rim Elange ex-
tensions.are-parallel to~t~e road su~ace dur,ing run-flat
operation of said rim when the ~ire mounted thereon is
deflated.
Accordin~ to a preferred aspect of the present
invention, this rim is combined with a pneumatic tire,
wherein the tire comprises an annular road-engaging tread
surface, sidewalls connecting the lateral edges of said
tread surface to annular beads and reinforcing plies
connecting said beads and passing through said sidewalls
and radially inward of said tread surface, wherein said
tire has an asymmetric sidewall construction, each said
sidewall has an insert of high modulus, low hysteresis
rubber compound located on its inner periphery, the insert
on the sidewall designed to be mounted on the inside of
the vehicle having a greater thickness than the corre-
sponding insert on the sidewall designed to be mounted on ~
the outside of the vehicle, said rim flange extensions ~ :
forming angles, as measured from a-plane parallel to the
axis of rotation of said rim, wherein said angle has a
negative value on the side of the rim designed to be mounted
on the inside of the vehlcle and a positive value on the
side of the rim designed to be mounted on the outside of
the vehicle, whereby when the tire is run flat said rim
flange extensions are both parallel to the road surface
and each sidewall is equally loaded.
The location of the inserts in the tire yields
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a structure having a column type effect. The column effect
means that the run flat tire structure is loaded along a
line which bisects the tire shoulder, the sidewall insert,
the support member and the rim flange ex-tension. During
run flat o~eration the shoulders of the ~ire, the sidewall
inserts and members are placed into compression. The cord
material in the tire, due to the presence of the inserts,
remains in tension during run flat operation and does not
undergo a compression~tension cycle.
The angle formed by the rim flange extension
located on the side of the rim designed to be mounted on
the outside of the vehicle is said to be in a positive
direction, when viewing the cross-section of the rim when
mounted on a vehicle from the front of the vehicle, the
rim flange extension is angled upward toward the axis of
rotation of the rim~tire combination (angled away from the
road surface). Conversely, the rim flange extension on the
side of the rim designed to be mounted on the inside of
the vehicle is said to be angled in a negative direction,
when viewing the cross-section of the rim when mounted on
the vehicle from the front of the vehicle, the rim flange
extension is angled away from the axis of rotation (angled
toward the road surface).
The angle that these rim flange extensions form
with the plane parallel to the axis of rotation of the
rim may varie from 1 to 3 in the positiv~ direction on
the outside rim flange and from 1 to 3 in the negative
direction on the inside rim flange. This angulation o t~e
rim flange extensions provides a structure which will
equally distrib~te the load of the vehicle on each tire
sidewall when the tire is mounted on the vehicle in its
standard configuration.
~Llf~7Z3L:lL
Normally, a tire is set on a vehicle in a front
position so that it has a positive camber between .5 and
2. This means that the tire will be tilted in at the road
engaging area when viewed on a vehicle from the front o
the vehicle. When the ~ire is run fla~ ~his posi~ive cam~er
is accentuated so that the angle is usually between approxi-
mately positive 2.5 and 4. The rim of this inventiOn with
its rim flanges angled in different directions counteracts
the unequal load that the camber places on the sidewall of
the tire. This is accomplished by the angle change from a
plus value on the outside rim flange extension to a minus
value on the inside. The geometry of this and its exact
relationship to the camber of the tire will be evident
from a view of the drawings. - `
The angle of the rim flange extensions may or may
not be equal. That is the positive and negative values on
each side may be the same, say 2 degrees, or they may be
different, positive may be 1.5 degrees, negative may be 2
degrees.
The radially outward surface of the rim flange
extension will bear the weight of the tire during run-1at
operation and will be in contact with the tire during this ;~
operation. Conversely, when the tire is operated under normal ~
conditions of rated load and inflation, the rim flan~e ~;
extensions dc not contact the tire~ This means th~t normal
ride comfort characteristics will be maintained during normal
operation of the tire. During run-flat operation of the
tire, due to the structural features identified above in
the tire sidewalls (the asymme~ric insert construction) and
the asymmetric nature of the rim flange extensions' angu
tions, the sidewalls of the tire will be ~miformly and
equally loaded. This will result in a minimum of lower
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sidewall movement.
The radially outer surfaces of the rim flange
extension may be provided with one or a series of protrusions
that extend radially outward from the surface. Thes~ pro-
trusions mechanically engage the lower sidewall of -the tire
or the support member, if the tire has one in its lower
sidewall, during run-flat operations and thereby prevent the
tire from rotating or moving in relation to the rim during
run-flat operation. This movement may be a rotation in re'
lation to the rim or a bead unseating.
The rim of this invention may also contain an annular
reservoir member located thereon. This reservoir member may
be used to store a liquid cooling and/or lubricating type
material that will be injected into the tire by an appropriate
pressure sensitive valve when the tire is run flat. During
the loss of air by a tire as it is going ~lat a valve which
connects the exterior reservoir member to the sir cavity of
the tire will be actuated so that the fluid in the reservoir
member will be free to move into the tire cavity. Such
movement will be accomplished by the centrifugal force that
is applied to the fluid in tlle reservoir member during
normal operation and rotation o~ the tire. The reservoir
member is located on the rim at a position radially inward
of the bead seats on the exterior of the rim. The member
may be attached to the rim by any standard meansO
This structure will become more evident from a
review of the drawings, given as example only~ without any
limitative manner.
Figure 1 is a cross-sectional view of a tire
and rim e~emplifying the structures of this invention when
the tire is mounted on the rim, inflated to rated inflation
and subject to rated load;
Figure 2 is a cross-section of the tire of ~igure 1 wherein
the tire is under load and with no inflation pressure; that
is, its run flat configuration.
The tire-rim combination is shown as having a
camber angle " a", as defined from a perpendicula~, line
A, to the road surface, line X, and the camber angulation
line B, that intersects perpendicular X at point Y on the
axis of rotation of the combination. This angulation is shown
with the angle in a positive direction so that the tire-rim
combination is tilted inward toward the center of the vehicle
body in the road contacting area.
The rim is shown generall~ as 1 having an annular
drop center area, 2, which has bead seats, 3, located axially
outward of either side of the drop center area. The bead seats
have rim flanges, 4, extending axially outward from the bead
seats and the rim flanges have rim flange extensions, 5,
extending axially outward from the edges thereof.
In the rim of this invention, the rim flange
extensions form an angle to a plane parallel to the axis of
rotation of the rim. Such planes are shown as broken lines
C and C' in ~igure 1. In Figure 1 the side of the combination
that is designed to be mounted toward the vehicle ~the
inside) is the right hand side and side of the combination
that is designed to be mounted away from the vehicle (the
outside) is the left hand side. The rim flange extension,
5, on the vehicle side ~right hand side of Figure 1) is
located at an angle 1I d" formed by line D in relation to
line C. This angle is inclined in a direction toward the
road surface or away from the axis of rotation of the tire
and has negative value. The rim flange extension, 5~ located
on the outside of the tire ~left hand side of Figure l) is
inclined upward toward the axis of rotation oE the tire
or away from the road surface. This has a positive value
and is depicted as the angle " e" formed by the line E in
relation to line C'.
The angulation of the rim flange extension, 5, on
the vehicle side of the rlm (right hand side of FicJure 1)
is preferably from -1 to -3 and on the outside side o~ the
rim (left hand side of ~igure 1) is preferably from +1 to
+3. The values of these angles may be equal (with opposite
signs), or they may be different. The angulation value is
dependent upon the construction of the tire which is designed
for the rim and the amount of camber in the vehicle that
the rim is designed to be mounted on. These factors may
result in an angle greater than 3 and on unequal angles
from one side of the rim to the other.
The angles must be balanced with the vehicle
camber and the construction to yield a combination in which
the tire sidewalls are approximately equally loaded under
run flat conditions. This equal loading is evidenced by both
rim flange extensions being parallel to the road surface and
temperature data taken in the support member, mid-sidewall
and shoulder area of each sidewall during run~flat operation.
The outer surface of the rim flange extension may
contain protrusion, 6, which are designed to grip a portion
of the tire when the tire is run flat and in contact with
the rim flange extensions. In this embodiment the protrusion
is an annular rib. It may be circumferentially continuous
or discontinuous.
The,rim may also contain an annular reservoir
member, 7, which is located radially inward of the bead seats.
This reservoir member is connected to the air cavity defined
by the tire and rim by a pressure sensitive valve (not
shown). This reservoir member may contain a cooling and/or
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a lubricant fluid that is displaced into the air cavity
when the air pressure in the air cavity goes below a certain
level thereby actuating the valve. The fluid is displaced
into the air cavity by centrlfugal Eorce that occurs during
the revolution of the rim-tire assembly.
The tire is shown generally as 10, having annular
road engaging tread surface, 15, that is connected to
sidewalls 17, at its lateral edges. The sidewalls terminate
in annular bead bundles, ll, in the bead area of the tire.
Reinforcing carcass plies, 12, extend from one bead bundle
to the other through the sidewalls and the tread area of the
tire. The inner periphery of the sidewalls of the tire
contain inserts 13 and 14.
The inserts are located inwardly of the carcass
reinforcing material or plies. The inserts are located at
the midpoint of the sidewall; that is, the distance half
way between the bead seat and the road engaging tread
surface when the tire is mounted and inflated under normal
conditions. The insert, 14, on the side of the tire designed
~0 to be mounted~ toward the vehicle, is thicker in cross-section
and is, therefore, bulkier than the insert, 13, on the side
~f the tire designed to be mounted on the outside of the
vehicle. This difference in bulk compensates for the unequal
loading that will occur when the tire is mounted on the rim
under run flat conditions. This asymmetric nature of the ~
insert in the tire sidewalls combats this disproportionate ~`
loading condition.
The asymrnetric nature of the angulation of the
rim flange e~tensions described above also combats this
condition. The combination of these two asymmetric conditions
yields the best balance of loading on the sidewalls al-
though the condition in the tire or the rim, by itself,
combats a portion of the disproportionate loading.
The tire also contains support members, 16,
located in the lower sidewall areas. These members contain
a surface, 18, that is adapted ko correspond ~o and ride
upon the rim flange extenslons when the kire ls run ~lat.
During no~mal operation of the tire under normal conditions
of inflation and load, the support members of the tire, 16,
will not be in contact with the rim flange extensions.
The radially inward, approximately flat surface,
18, of the support member is substantially parallel to the
axis of rotation of the tire. This flat surface, lB, may
also have an axial length approximately equal to the axial
width of the rim flange extension.
Figure 2 depicts the tire and rim of Figure 1
when the inflation pressure in the tire has been lost and
the tire is bearin~ the vehicle load. This is known as the
run flat condition of the tire. The asymmetric nature of
the sidewall inserts and the asymmetric nature of the angu-
lation of the rim flange extensions results in an equal
distribution of the vehicle load on both of the sidewalls.
The presence of the inserts additionally maintains the tire
reinforcing body, 12, ln tension and does not permit this
body to go into a tension-compression cycle. The load sup-
porting structure as shown in the Figure 2 is a dual column
type wherein each shoulder area of the tread, each sidewall
insert, each tire support member and each rim flange ex-
tension for one column to support the weight of the vehicle.
The reservoir member, 7, is preferably a reinforced
plastic tube which is either fastened or snapped into place
on the external surface of the rim. The location of this
tube outside of the tire cavity defined by the rim and tire
facilitates easy mounting of the reservoir member and the
tire. Replacement of the reservoir member and refilling of
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1::a27;~
the reservoir member is also easier with this location.
The reservoir member may also be considered at heat sink to
draw heat away from the carcas~ of the tire during normal
operation.
The reservoir member preferably contains a coollncJ
and/or a lubricant liquid. This liquid can be any oE the
known types already taught for internal lubrication o~
tires when run flat or a material that acts as a coolant to
yield a flat tire that has a lower running temperature.
~ 185/65R14 steel belted radial tire was manu-
factured in accordance with this invention and mounted on
a 14 inch diameter rlm that was modified to conform with
the rim structure of this invention. The rim width as
measured from one bead seat to the other was 4.5 inches and
the rim flange extension extended 1.1 inches beyond the bead
seat. The angulation of the rim flange extensions was 2;
that is, a -2 on the vehicle side and a ~2 on the outside.
Each outer surface of the rim flange extensions contained
a circumferential rib for bead retention.
The tire had one body ply of 840/2/3 nylon fabric
the cords of which extended in a radial direction; two tread
plies of steel cords, wire bead bundles and a road engaging
tread surface. The tire contained a support member in the
lower sidewall areas whose radially inward surface was
adapted to correspond to the outer surface of the rim flange
extensions. The section height of the tire was 5 inches and
the section width was 7.5 inches.
The tire contained inserts at the mid-sidewall
area located inside the rein~orcing body ply. The insert in
the ~ehicle side was .25 inches thick whereas the insert in
the outside was .20 inches thic~. The modulus of the rubber
compound utilized in the inserts was 1300 psi et 200%
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elongation and the running temperature (hysteresis) of the
rubber compound was between 190 F and 230~ F.
Tires of this construction were tes-ted on a series
of tests to determine the stability o:E this cons~ruc-tion
when the tire was run under normal condi~io~s and run ~lat
and the durability of the tire when the tire was run flat.
Tires of this construction were compared to tires with
inserts that were evenly balanced from one sidewall to the
other and were at different locations in the sidewall. These
control tires were run on a re~ular rim and on a rim with
extended rim flanges. The results of run flat tests on
these three combinations are set out in the table below.
It is evident from these tests that the combination of the
asymmetric sidewall tire with the asymmetric rim flange
extensions yields a structure that performs in an improved
manner.
Run-flat
mileage to Maximum
failure sidewall Vehicle
Feature (50 mph~ Tempera- Side Mileage
Average ture F
two tires Outside
Control
Tire 10.3 325 307 lQ
Regular ~
rim .
Control :.
tire
Extended 13.9 374 31~ 15
Elange ~::
rim
Asymmetric
Tire 50* 301 295 30
Extended .
flange rim
"
*Removed, no failure
It is understood that this invention is particu-
larly suited for passenger vehicle tires although it may
also be applied to truck and ~irplane tires whe~e the ti~e
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7Z~
is operated under an initial cambe.r or operates under a
camber condition when the tire is run flat. The features
of the tire not discussed may be any of the standard features
manufactured using standard materials by standard method.
For example, the reinforcing body may contain cords o
nylon, rayon, or aramid; the tread ply belt may contain
cords of aramid, glass or steel.
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