JP3391589B2 - Radial tire and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial tire suitable for passenger cars, which is capable of improving vibration riding comfort and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A radial force variation (hereinafter referred to as "RFV") is a factor that influences the vibration and riding comfort performance of a vehicle. RFV
Is a force of load fluctuation that appears vertically on the tire rotation axis when the tire is rotated by applying a load.
Is transmitted to the vehicle via the axle, reducing the riding comfort.

Generally, RFV has a deep relationship with a radial runout (hereinafter referred to as "RRO") which is a vertical vibration when a tire having an unbalanced shape is rotated, and it has been found that the RFV can be reduced by reducing the value. is doing.

As a means for reducing the RRO, for example, polishing the tread surface with a perfect circular buff is effective in the case of a new tire, but the root cause has been investigated and removed. In many cases, the deterioration of the RFV is surfaced such that uneven wear occurs or the tire profile changes as the tire is used for running.

It has also been attempted to reduce the RRO by dispersing the seams of tire constituent members such as tread rubber and belt ply in the tire circumferential direction. It is not something that will be lost, and its effect is not yet sufficient.

[0006]

As described above, the RFV
When the tire is new, even if the tire is within a predetermined standard, it may increase due to running of the tire even if uneven wear does not occur in the tread portion. Therefore, the RFV must be considered not only when new tires are used, but also at a constant level at all times when it is actually mounted and used in a vehicle, but a proposal that can realize this is presently made. Absent.

By the way, in a tire used for running, the wear condition of the tread portion, the tire internal pressure, and the like change every moment during running, and in particular, if the carcass profile changes due to the latter change in the internal pressure, the RRO in the tire circumferential direction. In recent years, it has been found that the RFV also greatly changes and the RFV is increased. Therefore, if the shape change of the carcass profile is small even if the tire internal pressure changes, the RFV
Can be expected to be suppressed.

In view of such circumstances, the present invention was devised from the viewpoint of minimizing the shape change of the carcass profile even when the tire internal pressure changes, and not only when the tire is new, but also when the tire is in use. An object of the present invention is to provide a radial tire capable of suppressing RFV, improving vibration riding comfort performance of a vehicle, and maintaining the improved performance over a long period of time, and a manufacturing method thereof.

[0009]

According to a first aspect of the present invention, there is provided a cord having a turn-back portion that bends around the bead core of the bead portion from the tread portion to the side wall portion from the inner side in the tire axial direction to the outer side. A radial tire having a carcass arranged in the radial direction and a belt layer arranged radially outside of the carcass and inside the tread portion, and having a wide rim wider by 0.5 inch than the rim width of the standard rim. The amount of protrusion of the carcass profile in the tire meridional section when the tire is mounted and subjected to an internal pressure change process for changing the internal pressure from 5% of the regular internal pressure to 100% of the regular internal pressure is larger than that of the bead portion in the buttress portion. The carcass when it is mounted on a narrow rim that is larger than the standard rim and is 0.5 inch narrower than the rim width of the standard rim, and the internal pressure change process is performed. Protruding amount of profile is a radial tire, wherein the larger the bead portion than buttress portion.

According to the second aspect of the present invention, there is provided a turn-back portion from the tread portion to the side wall portion, the turn-around portion of the bead core of the bead portion is turned back from the inner side in the tire axial direction to the outer side, and the cord is arranged in the radial direction. Vulcanization for vulcanizing a raw tire cover in a vulcanization mold during a process of manufacturing a radial tire having a carcass and a belt layer arranged on the outer side in the radial direction of the carcass and on the inner side of the tread portion. In a method for manufacturing a radial tire including a step and a post-cure inflation step in which a vulcanized tire after this vulcanizing step is filled with an internal pressure larger than atmospheric pressure and held for a certain time, the vulcanizing step is: The distance between the outer surfaces of the beads,
While using a vulcanization mold having a bead molding surface with a clip width that can be molded to be larger than the rim width of the standard rim to be mounted, the post cure inflation step,
The vulcanized tire had a rim width larger than that of the standard rim and 1.5 inches added to the rim width of the standard rim.
A method of manufacturing a radial tire is characterized in that the radial tire is mounted on a rim body having an increase width of not more than an inch and not more than a clip width of the vulcanizing mold.

[0011]

In FIG. 1, the carcass profile 9 in a state in which the rim width of the rim to be mounted is changed to three types and the inner pressure of 5% of the normal inner pressure is filled is shown by a solid line, and the state when the inner pressure of 100% is filled. Are each shown as a conceptual diagram by a dotted line.

As shown in FIG. 1, the radial tire of claim 1 is mounted on a wide rim JA which is 0.5 inch wider than the rim width of the standard rim J, and is filled with an internal pressure of 5% of the normal internal pressure. As shown by reference numeral 9A, the carcass profile 9 in the meridional section of the tire when the internal pressure change processing for changing the internal pressure to 100% of the internal pressure has a larger amount V1 of protrusion in the buttress portion 10 than in the bead portion 4. .

Further, the carcass profile 9 when mounted on a narrow rim JB narrower by 0.5 inch than the rim width of the standard rim J and subjected to the internal pressure change processing, as shown by reference numeral 9B, is the protrusion thereof. The amount V2 is the buttress portion 10
The bead portion 4 is larger than the bead portion 4.

Such a radial tire has the above-mentioned wide rim J
When mounted on a standard rim J corresponding to an intermediate rim width between A and a narrow rim JB and subjected to the internal pressure change process,
In the carcass profile 9, as shown by reference numeral 9C, the protrusions of the buttress portion 10 and the bead portion 4 cancel each other, so that the protrusions of both can be found to be uniform and the equilibrium point at which the absolute amount is small can be found.

That is, in the radial tire, the carcass profile 9 is R depending on the change of the internal pressure during use of the tire.
As a result of only a small and uniform shape change that hardly affects RO and suppressing the RFV, the vibration riding comfort performance of the vehicle can be significantly improved.

Next, the method for manufacturing a radial tire according to claim 2 is a method suitable for manufacturing the radial tire according to claim 1, wherein the vulcanization step of the tire as shown in FIG. A vulcanization mold 12 having a bead molding surface 11 with a clip width CW that can be molded by making the distance between the bead portion outer surfaces 4a contacting the rim flange JF during mounting larger than the rim width RW of the standard rim J to be mounted is used. Do it.

Here, how the carcass profile 9 is deformed by the above-mentioned internal pressure filling treatment and the relationship between the clip width CW of the vulcanization mold 12 and the standard rim width RW has been clarified by various experimental results. . 4 (A) to 4 (C), when the clip width CW and the standard rim width RW are matched, the shape change of the carcass profile 9 due to the internal pressure filling treatment is shown by a solid line at 5% of the normal internal pressure. Same 1
00% time is indicated by a dotted line.

When the carcass profile 9 shown in FIG. 4 (A) is an Otafuku type with a downward bulge, the buttress portion 10 radially outward of the carcass maximum width position is larger than the bead portion 4.

The carcass profile 9 shown in FIG.
Is based on the natural equilibrium shape theory, the carcass as a whole is approximately similar to the protruding shape, and when the carcass profile 9 in FIG. It was found that the bead portion 4 protruded larger than the buttress portion 10.

Similarly, FIGS. 5A to 5C show changes in shape of the carcass profile 9 due to the internal pressure filling process when the clip width and the standard rim width are changed,
The profile in the vulcanization mold is indicated by the one-dot chain line, and the normal internal pressure when mounted on the standard rim at 5% is indicated by the solid line.
The 0% time is indicated by a dotted line.

The clip width of the vulcanizing mold shown in FIG.
When the carcass profile 9 is larger than the standard rim width, the bead portion 4 is made larger than the buttress portion 10 by the internal pressure filling process, and the clip width and the standard rim width in FIG. In the case of the same, the entire carcass profile 9 projects in a substantially similar shape, and when the clip width is smaller than the standard rim width in the same figure (C), the buttress portion 10 is larger than the bead portion 4. It turned out to be a big protrusion.

From the above, in order to minimize the change in shape of the carcass profile 9 due to internal pressure filling, the shape of the carcass profile in the vulcanization mold should be a natural equilibrium type,
In addition, it is important to match the clip width CW with the standard rim width RW.

However, if the clip width CW and the standard rim width RW are matched, the spacing between the bead portions 4 and 4 tends to be narrowed, and the bladder BD (which can expand and contract toward the tire inner cavity during vulcanization). (Shown in FIG. 2) is difficult, and when the tire rim is assembled, a sufficient contact state between the bead portion 4 and the rim flange JF cannot be ensured and the workability of the rim assembly is deteriorated. Therefore, it is premised that the clip width CW of the vulcanization mold is set larger than the standard rim width RW so as not to deteriorate the productivity of such tires.

On the other hand, the vulcanization mold 12 is a diaper mold in which the carcass profile 9 during vulcanization is such that the inner side in the radial direction slightly bulges from the carcass maximum width position with respect to the profile based on the natural equilibrium shape theory. It is preferable to form the molding surface so that

Next, in the post cure inflation step (hereinafter referred to as "PCI step"), as shown in FIG. 3, the vulcanized tire 1B which has been subjected to the vulcanization step has a rim width PW.
Is larger than the standard rim width RW and 1.5 in the standard rim width RW
It is characterized in that it is mounted on the rim body 13 having an increase width of 1.5 inches or less including an inch and a clip width CW or less.

In general, in the vulcanization step, due to the presence of the molding surface of the vulcanization mold 12, sufficient tension cannot be applied to the carcass cord in the carcass ply, and the carcass cord is not in a fully extended state. Therefore, by performing the PCI process, the carcass profile can be fixed in a sufficiently extended state under a situation in which the carcass cord can be freely deformed, and the cord path elongation of the carcass due to the internal pressure filling is small, and by extension, the carcass profile 9 The change in shape can be made smaller.

In the PCI process, the bead portion 4 is formed in the clip width after vulcanization by using the rim body 13 having the rim width PW larger than the standard rim width RW and less than the clip width CW. The width of the bead portion can be made equal or narrower, but the bead portion is held in a shape wider than the standard rim width RW. Therefore, after the PCI process, by mounting the tire on the standard rim J, the interval between the bead portions 4 is narrowed.

As is clear from the above, vulcanization, PC
In the radial tire 1 that has undergone the process I, the carcass profile 9 has an Otafuku shape based on the natural equilibrium shape of the downward bulge, and the bead portions 4 are widened. If the carcass profile 9 is subjected to the internal pressure filling process, the protrusion of the buttress portion 10 based on the Otafuku shape and the protrusion of the bead portion 4 based on the narrowing of the bead portion 4 cancel each other as shown in FIGS. 4 and 5. By doing so, the two protrusions find an equilibrium point at which they are uniform and whose absolute amount is small.

In addition, as a result of the PCI step, the carcass cord is held in a stretched state due to uniform tension, and as a result, the elongation due to internal pressure filling is extremely small and can be neglected. 9
The absolute amount of protrusion can be made small, for example, 1 mm or less.

If necessary, by using this manufacturing method, the carcass profile 9 is firstly such that the amount of protrusion is substantially uniform in the buttress portion and the bead portion, and secondly, the absolute amount of the amount of protrusion is reduced. Thirdly, it is possible to provide a tire in which the shape change of the carcass profile is substantially similar and can be minimized, and fourthly, there is an effect that productivity is not deteriorated.

As described above, the carcass profile 9 is
Even if there is a change in internal pressure due to running, there is almost no change in shape,
As a result of reducing RRO in the tire circumferential direction and suppressing RFV, it is possible to improve the vibration riding comfort performance of the vehicle and maintain this performance for a long time.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claim 1 or 2 will be described below with reference to the drawings. As shown in FIGS. 1, 2 and 3, a radial tire 1 includes a carcass 6 which is folded back from a tread portion 2 to a side wall portion 3 at a bead core 5 of a bead portion 4 from an inner side to an outer side in a tire axial direction. And a reinforcing belt layer 7 located outside of the carcass 6 in the radial direction and inside the tread portion, and has a tapered shape extending from the bead core 5 between the main body portion 6a and the folded-back portion 6b of the carcass 6. A bead apex 8 made of rubber harder than the surrounding rubber composition is provided.

The carcass 6 has one or more cord plies in which a carcass cord made of an organic fiber such as aromatic polyamide, rayon, nylon or polyester is arranged in a radial direction of 70 to 90 degrees with respect to the tire equator C. It is formed by using.

The belt layer 7 is formed of a belt cord preferably made of steel, for example, 1 with respect to the tire equator C.
The inner and outer two layers of belt plies 7A and 7B arranged at small angles of 0 to 30 degrees are formed by overlapping in a direction in which the cords intersect with each other, so that the tread portion 3 can be strongly provided with a hoop effect.

Both ends of the inner belt ply 7A are formed wider than the outer belt ply 7B. The belt cord may be made of various cord materials such as organic fiber other than steel.

As shown in FIG. 1, this radial tire has a wide rim JA that is 0.5 inch wider than the standard rim width RW.
Mounted on the vehicle, and subjected to an internal pressure change process for changing the internal pressure from 5% of the internal pressure to 100% of the internal pressure, the amount of protrusion of the carcass profile 9A in the meridional section of the tire is larger than that of the bead portion 4. The buttress portion 10 is set larger.

Further, when the carcass profile 9B is mounted on the narrow rim JB which is 0.5 inch narrower than the standard rim width RW and the internal pressure change process is performed, the protrusion amount of the carcass profile 9B is larger than that of the buttress portion 10 in the bead portion 4. The larger is set.

Such a radial tire has the above-mentioned wide rim J
When mounted on a standard rim J corresponding to an intermediate rim width between A and a narrow rim JB and subjected to the internal pressure change process,
As for the protrusion of the carcass profile 9C, the buttress portion 10 and the bead portion 4 cancel each other out so that they can be found to be uniform with respect to each other, and an equilibrium point of the protrusion can be found in which the absolute amount is small.

If the change in the shape of the carcass profile 9C due to the change in the internal pressure is small, the carcass profile has almost no effect on the RRO even if the internal pressure changes while the tire is in use, and the RFV is suppressed to improve the vibration ride comfort performance of the vehicle. As mentioned above, it can be greatly improved.

Here, the standard rim J is JATMA.
Refers to the standard rim in the standard, and the regular internal pressure is JATMA
Refers to the air pressure specified in the standard. The carcass profile is shown as the thickness center line of the main body portion 6a of the carcass 6.

A manufacturing method suitable for manufacturing the radial tire 1 will be described below. First, in the vulcanization step of vulcanizing the raw tire cover 1A in the vulcanization mold as shown in FIG. 2, the distance between the bead portion outer surfaces 4a is set to be larger than the rim width RW of the standard rim to be mounted. It is necessary to use a vulcanizing mold 12 having a bead molding surface 11 having a clip width CW that can be molded. In this embodiment, the clip width CW is 0.8 inches added to the standard rim width RW. The width is illustrated.

It is well known that the above-mentioned natural equilibrium shape theory is proposed as a carcass profile whose shape is less likely to change due to internal pressure filling. This natural equilibrium shape theory means that when the axial end point of the belt layer and the bead portion fixed position point are given (under the assumption that these two points do not move).
This is a theory in which the carcass profile can be uniquely obtained by defining either the carcass code path or the carcass maximum width.

The feature of this natural equilibrium shape theory is that the tension acting on the carcass cord is constant. Therefore, if it is considered that the carcass cord is stretched, it can be said that the carcass profile based on this theory can be expanded and deformed substantially uniformly from the original shape and the deformation amount can be kept small.

Regarding the natural equilibrium shape theory, see W. H
offerberth, Kautsch. Gummi
(8-1955, 124-130) for details.

Since the carcass profile based on such a natural equilibrium shape theory can apply the film theory to, for example, the sidewall portion region sandwiched by the tire axial end portion of the belt layer 7 and the bead apex 8 tip end. Although the natural equilibrium shape theory can be adopted, the following modifications are made to the crown region located on the tire radial inner side of the belt layer 7 of the carcass 6 and the bead portion region on the tire axial inner side of the bead apex.

The crown region is between DP on the coordinate system having the y axis on the tire rotation axis and the z axis in the radial direction passing through the tire equator position as shown in FIG. It is considered that this region shares the tire internal pressure with the carcass cord of the carcass 6 and the belt cord of the belt layer 7.

Here, the belt internal pressure distribution rate by which the belt layer 7 shares the tire internal pressure is expressed by the following equation 1 using Tb as a function of z.
Can be approximated and expressed.

[0048]

[Equation 1]

However, a is optional depending on the belt layer,
The belt internal pressure sharing rate Tb has a parabolic shape in which when a = 0, the uniform pressure sharing of τo is achieved over the entire area of the belt layer 7, and when a = τo, the pressure sharing is 0 at both ends of the belt layer and τo is on the equator. . rp and rd are coordinate values.

Next, the bead apex 8 of the bead portion 4
Te is the bead internal pressure sharing ratio in which the tire internal pressure is shared by r
It can be approximately expressed as a function of
Rb is the r coordinate at the inner end of the bead apex, r
e is the r coordinate at the tip of the bead apex, and τe is the pressure sharing rate at the inner end of the bead apex.

[0051]

[Equation 2]

In such a case, from the balance condition between the cord tension tc acting on the carcass cord and the tire internal pressure p, if the number of carcass cords around the tire is N between the radius of curvature Rs of the cross section at the point of radius r, then N The relational expression 3 holds.

[0053]

[Equation 3]

Note that Tc is a ratio of internal pressure of the carcass 6 to r
And Tc = 1−Tb in the crown region.
(Tb: belt internal pressure share), T in the bead area
c = 1-Te (Te: bead internal pressure sharing rate), and otherwise Tc = 1. Further, the Rs can be expressed as in Equation 4 from the geometrical relation.

[0055]

[Equation 4]

By substituting the equation 4 and the carcass internal pressure distribution rate Tc into the equation 3, the crown region (between D and P), the side wall region (between E and D) and the bead region (E and B) are substituted.
5) to form a carcass shape by integrating
It can be given as 7.

[0057]

[Equation 5]

[0058]

[Equation 6]

[0059]

[Equation 7]

However, B in the equations 5 to 7 is as shown in the equation 8.

[0061]

[Equation 8]

The carcass profile 9 at the time of mounting the standard rim, which is based on the natural equilibrium shape, can be drawn by using the equations expressed by the above-mentioned equations 5 to 7. As for the above-mentioned numbers 5 to 7, as shown in FIG. 7, carcass diameter: rp, carcass width: W, rim width: RW, belt width: BW, bead portion thickness: CT, bead apex height: BH
The carcass profile can be drawn by appropriately giving (from the bead base line BL), belt internal pressure sharing ratio Tb, and bead internal pressure sharing ratio Te.

Further, the carcass diameter: rp, the carcass width: W, the rim width: RW can be appropriately determined by giving standards such as JATMA and JIS and various rubber gauges, and the belt width: BW, the carcass width. : Smaller than W and carcass width: W, {1.25-
It is set to be larger than the coefficient multiplied by 0.01 × (flatness ratio)}.

In this embodiment, the bead internal pressure sharing ratio Te
Is 0.7, and the belt internal pressure share Tb is a value when the tread portion 2 of the carcass profile 9 is the flattest.

By giving appropriate numerical values in this way,
The carcass profile 9 when the tire is mounted on the standard rim can be drawn, and the code path of the carcass 6 can be calculated from this. The calculated code path of the carcass 6 is fixed and vulcanized in the vulcanization mold. The carcass profile 9 in the inside may be widened to the rim width: RW to the clip width CW, and an appropriate numerical value may be given based on the molding surface of the mold.

In this way, the clip width CW of the vulcanization mold 12
When the width is wider than the standard rim width RW, when the standard rim J is mounted on the standard rim J, the bead portion interval is narrowed as described above, and the bead portion 4 is protruded by the internal pressure filling process. Therefore, the carcass profile 9 is substantially the same as the above-mentioned theoretical curves of the above-mentioned formulas 5 to 7 or is an Otafuku type having a downward bulge inward in the tire radial direction, and by the protrusion of the buttress portion 10 by the internal pressure filling process, The protrusion of the bead portion 4 and the protrusion of the bead portion 4 can be offset from each other to make the protrusion itself uniform and small.

The clip width CW varies depending on the tire size. For example, the tire size is 205 / 65R.
In case of 15, it is preferably 0.5 than the rim width of the standard rim.
Greater than one inch and less than or equal to 1.5 inches, preferably 0.
It is about 8 inches (20.32 mm). In other words, it is about 6 to 20% of the nominal tire size (205 mm).

When the increase width is 0.5 inch or less, the bead 4 is formed.
On the contrary, if it exceeds 1.5 inches, the change of the carcass profile is too large to achieve the purpose.

Next, in the PCI step, as shown in FIG. 3, the vulcanized tire 1B which has been subjected to the vulcanization step has a rim width PW larger than the standard rim width RW and a standard rim width RW of 1.5 inches. Is added to the rim body 13 having a width of 1.5 inches or less and a clip width CW of the vulcanization die 12 or less. In this embodiment, the standard rim width RW is 0.5. It has been increased by an inch (12.55 mm).

As described above, the PCI process is performed by using the rim body B satisfying the relation that the rim width PW is larger than the standard rim width RW and less than or equal to the clip width CW of the vulcanizing mold, preferably smaller than the clip width. , The carcass cord can be stretched while maintaining or narrowing the space between the bead portions 4 that are widened during the vulcanization process, and the shape of the carcass profile can be maintained, and the deformation of the bead portion 4 when the standard rim is attached can be prevented. Can be moderated.

It is necessary to pay attention to the following three points in the PCI process. First of all, the vulcanized tire 1B has at least 90 to 100%, preferably 100% of the normal internal pressure.
That is, the tire is allowed to freely deform by filling the inner pressure of No. 2 and holding only the bead portion 4 in such a state.

If the load of the internal pressure cannot sufficiently act and the free deformation of the tire cannot be allowed, the carcass profile 9 cannot be maintained in the equilibrium state in which the carcass cord is extended, and the carcass is filled at the time of the normal internal pressure filling. While the cord path is changed to adversely affect the shape change of the carcass profile 9, conversely, when it exceeds 100% of the normal internal pressure, an excessive load is applied to the carcass cord and durability is deteriorated, which is not preferable.

Secondly, in the PCI process, the temperature of the tire is controlled to about 80 to 160 degrees Celsius while utilizing the residual heat during vulcanization. If the temperature exceeds 160 ° C., rubber burning or the like will occur and the product value will be impaired, whereas if it falls below 80 ° C., the carcass cord will tend to contract, which is not preferable.

Third, the PCI process is to maintain the internal pressure filling state and temperature control for about 10 to 20 minutes. The lower limit of 10 minutes is the minimum time for achieving the original effect of the PCI process, and if it is less than this, sufficient elongation cannot be imparted to the carcass cord. Because it is inferior in sex.

The radial tire that has undergone the vulcanization process and the PCI process as described above is mounted on a wide rim wider by 0.5 inch than the rim width of the standard rim, and is filled with 5% of the normal internal pressure to a normal internal pressure. The protrusion amount of the carcass profile when the internal pressure change process to change to 100% internal pressure is larger in the buttress part than in the bead part, and conversely it is mounted on a narrow rim that is 0.5 inch narrower than the rim width of the standard rim. Then, when the internal pressure changing process is performed, it is possible to set a carcass profile in which the bead portion protrudes more than the buttress portion, and in this example, each protrusion amount can be stopped to about 1 mm or less. That is, it is possible to manufacture a radial tire capable of changing the shape of the carcass profile as described in claim 1.

[0076]

[Specific example] Tire size 205 / 65R15 (standard rim rim width RW: 6 inches), vulcanization mold clip width 6.8 inches, PCI process rim body rim width 7 inches, 6.5 Three types of inches and 6 inches are set, and a tire according to the manufacturing method of claim 2 is prototyped based on the specifications of Table 1 (Example), and a tire manufactured by a method other than the manufacturing method of Claim 2 (conventional example). Also, Comparative Examples 1 to 5) were prototyped and tested. In the conventional tire, the carcass profile in the vulcanization mold is based on a substantially single arc shape. The test procedure is as follows.

A) Change in shape of carcass profile Narrow rim narrower by 0.5 inch than rim width of standard rim,
The tire is mounted on a wide rim of the same size of 0.5 inch, the inner pressure filling process is performed, and the shape change of the carcass profile before and after the change is recorded by using an X-ray CT measuring device, and the amount of protrusion and the state thereof are recorded. It was confirmed.

(B) Vibration Ride Comfort Performance For each tire, the force variation (FV) was measured when the tire was new and after running for 12,800 km, and is displayed as an index with the conventional example being 100. The smaller the value,
It shows that the FV is small and the vibration riding comfort is excellent. In addition, as for the traveling condition, while using the FV measuring machine,
Load 468kgf, regular internal pressure 2.0KSC, standard rim 6.
It was carried out under the condition that the positive and negative slip angles were changed every 1600 km at 0JJ × 15 and a slip angle of 1 degree. The test results are shown in Table 1.

[0079]

[Table 1]

As a result of the test, it was confirmed that the tires of the examples according to the manufacturing method of claim 2 had a small FV both when new and after running, and particularly small after running.

[0081]

As described above, according to the present invention, the RFV can be suppressed not only when the tire is new, but also after the tire is used, the vibration riding comfort performance of the vehicle can be improved, and it can be maintained for a long time. Radial tires may be provided.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a shape change of a carcass profile of a radial tire of the present invention.

FIG. 2 is a cross-sectional view illustrating the vulcanization of a radial tire.

FIG. 3 is a cross-sectional view for explaining a PCI process.

FIG. 4A to FIG. 4C are diagrams for explaining the shape change of the carcass profile due to the internal pressure filling process.

5 (A) to (C) are diagrams for explaining the shape change of the carcass profile due to the internal pressure filling process.

FIG. 6 is a diagram for explaining a carcass profile.

FIG. 7 is a diagram for explaining a carcass profile.

[Explanation of symbols]

2 tread section 3 Side wall part 4 bead section 5 bead core 6 carcass 7 Belt layer 8 bead apex 9 carcass profile 10 Buttress Club 11 Bead molding surface 12 Vulcanizing mold 13 rim body

Continuation of front page (51) Int.Cl. ⁷ Identification code FI // B29K 21:00 B29K 21:00 105: 24 105: 24 B29L 30:00 B29L 30:00 (56) Reference JP-A-8-142602 (JP, A) JP 61-235107 (JP, A) JP 62-275805 (JP, A) JP 58-161603 (JP, A) JP 1-202502 (JP, A) Actual Kai 58-96927 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60C 3/00-3/08 B29C 33/02 B29C 35/02 B29D 30/00-30/72 B60C 9/00-9/30

Claims (2)

(57) [Claims] Claims: 1. A carcass having a turn-back part that bends around the bead core of the bead part from the tread part to the side wall part from the inner side to the outer side in the tire axial direction, and the cords are arranged in the radial direction. A radial tire having a belt layer arranged on the outer side in the radial direction and on the inner side of the tread portion. The radial tire is mounted on a wide rim wider by 0.5 inch than the rim width of the standard rim, and the internal pressure is 5% of the normal internal pressure. The amount of protrusion of the carcass profile in the meridional section of the tire when the internal pressure change process that changes the internal pressure to 100% of the normal internal pressure is larger in the buttress portion than in the bead portion, and the rim width of the standard rim is large. The amount of protrusion of the carcass profile when mounted on a narrow rim narrower than 0.5 inch and subjected to the internal pressure change process is Radial tire characterized in that the larger the bead portion than less section. 2. A carcass having a turn-back part that goes back from the tread part to the side wall part and turns back around the bead core of the bead part from the inner side to the outer side in the tire axial direction, and a cord arranged in the radial direction. A vulcanization step of vulcanizing the raw cover of the tire in a vulcanization mold during the step of manufacturing a radial tire having a belt layer arranged radially outside and inward of the tread portion;
In a method for manufacturing a radial tire including a post cure inflation step of filling the vulcanized tire after this vulcanization step with an internal pressure higher than atmospheric pressure and holding the same for a certain period of time, the vulcanization step includes an outer surface of a bead portion. While using a vulcanization mold having a bead molding surface of a clip width that can be molded with a distance between them being larger than the rim width of the standard rim to be mounted, the post cure inflation step is performed by the vulcanized tire. To a rim body having a rim width larger than the rim width of the standard rim and less than or equal to the 1.5-inch increase width obtained by adding 1.5 inches to the rim width of the standard rim, and less than or equal to the clip width of the vulcanizing mold. A method for manufacturing a radial tire, which is characterized by being mounted.