PNEUMATIC RADIAL TIRE WITH WATER-SPLASH CONTROL RIB

Abstract

The present invention relates to a pneumatic radial tire, and more particularly, to a pneumatic radial tire with water-splash control rib, wherein by optimizing the profile of the ring-shaped water-splash control rib on the sidewall along the circumference of the tire, the water-splash control, the increase in heat radiation, and the durability of the tire will be improved.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a pneumatic radial tire with water-splash control capability, and more particularly, to a pneumatic radial tire with water-splash control rib wherein by optimizing the profile of the ring-shaped water-splash control rib on the sidewall along the circumference of the tire, the water-splash control, the heat radiation increase, and the durability of the tire will be improved.

According to the present invention, when an heavy load vehicle, such as a truck or a bus, drives on the road that is covered with puddles of water or with some foreign substances, the water and the foreign substances such as stones, will not splash or bounce-off to the surrounding vehicles preventing reduced visibility of the drivers and the pedestrian, and will be free from getting splashed or hit by water or by foreign substances.

Moreover, the water-splash control can last for a long period of time and it can prevent loss of durability with good heat radiation performance, and therefore, improving safety when driving on the present pneumatic radial tire with water-splash control rib.

The present invention is keyed to heavy duty pneumatic radial tire, but it can also be applicable to tires on passenger vehicles, SUVs, and light-weight trucks.

DESCRIPTION OF THE RELATED ART

When a vehicle drives over a puddle of water, the tire will compress the water on the road, causing a water-splash.

At this moment, the water splashed inside towards the vehicle will disperse due to the bottom of the vehicle, however, the water splashed outside towards the surroundings can danger the safety of other vehicles by reducing visibility of the drivers.

FIG. 1 represents the configuration of the “water-splash control tire” by The Goodyear Tire in the U.S. Pat. No. 4,356,985 that suggests safety and decrease in accidents caused by water-splash.

As the figure shows, the water-splash control tire's basic technical configuration comprises sidewall that is installed with protuberance which is uniform in height and ring-shaped that extends circumferentially of the tire.

According to The Goodyear's water-splash control tire, which has a water-splash control ring-shaped protuberance (Z) (also known as “water-splash control ring”) positioned on the sidewall nearest to the tread or shoulder of a tire, even if the tread compresses water on the road so that it bounces off both sides of the tire, the water will be blocked by the protuberance (Z) formed along the sidewall, and therefore preventing water-splash or lowering the degree of water-splash.

As a result, even in the case where a heavy load vehicle driving on a heavy duty tire drives over a puddle of water, if the vehicle has the above tire installed, the water will not splash over to the surrounding vehicle's windshield, thus creating a safer driving condition.

However, because The Goodyear tire's “water-splash control tire” has a ring-shaped protuberance area of the sidewall, which can be thick, the end of the belt layer can be damaged by heat.

In other words, if the water-splash control tire's sidewall comprises a ring-shaped protuberance (Z), the amount of rubber in a specific area increases, therefore, the outmost part of the belt layer will interrupt the heat radiation of the tire when driving, and as a result, the heat at the end parts of the belt layers will accumulate heat and thus overheat so the end parts of the belts will separate, and ultimately, the durability of the tire will decrease and at the same time, create a hazardous driving condition on the road.

In order to fix the decrease in heat radiation in the water-splash control tire, Michelin, in the U.S. Pat. No. 6,460,584, and France Pat. No. 2792877, by optimizing the water-splash control ring's profile, suggested an improvement in the ‘water-splash control’ and the ‘heat radiation’ in the heavy duty tire with water-splash control.

For example, Michelin suggested in their invention that in order to efficiently overcome the heat generated by the tread area, especially to effectively release the heat in the both ends of the belt layers, at least a part of the upper profile of the ring-shaped protuberance has to be positioned below the average profile of the outmost belt.

Nevertheless, when this type of heavy duty water-splash control tire gets in contact with the surface that is uneven or when there is a heavy weight applied to the tire so that the ring-shaped protuberance gets in contact with the surface of the road, because of the outside pressure applied from the surface of the road towards upper profile of the protuberance, there can be a crack at the end of the protuberance or there can be a shortness in the life of the water-splash control due to the wear of the protuberance.

Especially, there is a possibility where a part of the protuberance will come apart due to a crack in the recessive part rather than other parts of the upper profile of the protuberance. This is due to the direction of the outside pressure applied to the protuberance and the direction of the progress of the crack is consistent. Therefore, if a part of the ring-shaped protuberance comes apart, the capacity of the water-splash control is no longer available.

OBJECTIVE OF THE INVENTION

The object of the present invention is to overcome the problems of the prior art described above by optimizing the profile of the ring-shaped water-splash control rib on the sidewall of the tire, so that the water-splash control, the heat radiation increase, and the durability of the tire will be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a conventional tire with water-splash control;

FIG. 2 is a summary cross-sectional view of an example of the present invention of the pneumatic radial tire with water-splash control;

FIG. 3 is a partial enlarged view of FIG. 2;

FIG. 4 is a partial enlarged view of FIG. 2;

FIG. 5 is a partial enlarged view of FIG. 2;

FIG. 6 is a cross-sectional view of an another example of the present invention of the pneumatic radial tire with water-splash control;

FIG. 7 is a partial enlarged view of FIG. 6;

FIG. 8 is a partial solid view of the pneumatic radial tire with water-splash control shown in FIG. 6;

FIG. 9 is a lateral view of the pneumatic radial tire with water-splash control shown in FIG. 6;

FIG. 10 is a solid view of an another example confronting FIG. 8;

FIG. 11 is a lateral view of the pneumatic radial tire with water-splash control shown in FIG. 10;

FIG. 12 is a suggestive cross-sectional view of an example of the present invention of the pneumatic radial tire with water-splash control;

FIG. 13 is a suggestive cross-sectional view of an example of the present invention of the pneumatic radial tire with water-splash control;

FIG. 14 is a partial enlarged view of FIG. 13; and

FIG. 15 is a cross-sectional confrontation view of FIG. 2.

EXPLANATION OF THE MARKS IN THE figures

• • 1: Tire.
  • 12: Layer of belts.
  • 20: Sidewall.
  • 100: Ring-shaped rib.
  • 110, 110′: Drainage groove or Drainage protuberance.
  • 120: Drainage channel along the circumference of the tire.
  • CC: Body ply.
  • 1B: #1 Belt.
  • 2B: #2 Belt.
  • 3B: #3 Belt.
  • 4B: #4 Belt.
  • CL: Center line of the cross-section of the tire or the vertical axis of the tire.
  • TD: Tread of the tire.
  • Gv: Groove of the tire.
  • SH: Maximum height of the tire from the horizontal axis of the tire.
  • SW: Maximum width of the tire from the vertical axis of the tire.
  • TW: Width of the tread of the tire.
  • A: Interior angle between the tangent line that passes through the endpoint of the tread and contacts the upper profile of the ring-shaped rib, and the continued horizontal line that horizontally passes through the endpoint of the tread.
  • B: Interior angle between the lateral profile of the tread and the continued vertical line that vertically passes through the endpoint of the tread.
  • C: Interior angle between the tangent line that passes through the endpoint of the tread and contacts the lateral profile of the sidewall, and the vertical line that vertically passes through the endpoint of the tread.
  • D: Interior angle between the tangent line that passes through the endpoint of the tread and contacts the lateral profile of the sidewall, and the horizontal line that horizontally passes through the endpoint of the tread.
  • E: Farthest point of the sidewall from the center line when pressure and weight is applied to the tire.
  • F: Farthest point of the ring-shaped rib from the center line when pressure and weight is applied to the tire.
  • 0: Basis point.
  • Ca: Continuation line that connects the average profile of the outmost belt.
  • Cb, Cc: Parallel curved line that is different in gap from the continuation curved line which connects the bottom of the groove of the tire.
  • Cd: Lateral profile of the sidewall.
  • CS: Continuation line that connects an arbitrary point on the sidewall and the center of rotation of the tire.
  • D1: Distance between the continuation line from the bottom of the groove of the tire and the parallel curved line Cc.
  • D2: Distance between the continuation line from the bottom of the groove of the tire and the parallel curved line Cb.
  • Dp: Height from starting point of the lower profile of the ring-shaped rib to the horizontal axis of the tire.
  • HL: Horizontal axis of the tire or a straight line that passes through the bottom of the bead among the straight lines that move parallel from the rotation axis of the tire.
  • La: Lateral profile of the tread.
  • Lb: Upper profile of the ring-shaped rib.
  • Lc: Vertical line that continues from the endpoint of the tread.
  • Le: Tangent line that passes through the endpoint of the tread and contacts the upper profile of the ring-shaped rib.
  • Ld: Tangent line that passes through the endpoint of the tread and contacts the lateral profile of the sidewall.
  • Pa: Endpoint of the lateral profile of the tread or the endpoint of the tread.
  • Pb: Intersecting point of the parallel curved line Cc and the continuation line of the lateral profile of the tread.
  • Pc: Intersecting point of the tangent line that passes through the endpoint of the tread and contacts the upper profile of the ring-shaped rib, and the horizontal curved line Cb.
  • Pe: Starting point of the lower profile of the ring-shaped rib.
  • Ra: Radius of the section of the curved line from the lateral profile of the tread to the upper profile of the ring-shaped rib in order to make the section smoother.
  • Rb: Radius of the curved line of the free end of the ring-shaped rib.
  • Rc: Radius of the recessive section which includes the starting point of the lower profile of the ring-shaped rib.
  • Rd: Radius of the imaginary circle such that the tangent of the circle contacts the upper profile of the ring-shaped rib that passes through the endpoint of the tread.
  • Re: Radius of the imaginary circle that has the perpendicular line coming from the tangent line (Le) that provides interior angle (A) starting at the lower profile of the ring-shaped rib as its diameter.
  • d: Angle between the drainage grooves or the drainage protuberances.
  • h: Distance between the intersecting point of the upper profile of the ring-shaped rib and lateral profile of the sidewall to the farthest point of the ring-shaped rib from the center line.
  • t: Length of the drainage groove or the drainage protuberance.

A preferred feature of the present pneumatic radial tire with water-splash control rib is the layer of belts deposited under the tread and a ring-shaped water-splash control rib (100) formed on the sidewall, wherein the upper profile of the rib is positioned above the continuation line which extends the average profile of the outmost layer of belt which is divided in to upper and lower profile.

In this case, a preferred way is to have the distance between the center line of the tire to the farthest point of the ring-shaped rib greater than the distance between the center line of the tire to the farthest point of the sidewall.

Moreover, to achieve the object as stated above, a preferred way of forming the rib is to satisfy the following condition between the two angles; an interior angle (A), which is an angle between the tangent line that passes through the endpoint of the tread and contacts the upper profile of the rib, and the continued horizontal line that horizontally passes through the endpoint of the tread, and an interior angle (D), which is an angle between the tangent line that passes through the endpoint of the tread and contacts the lateral profile of the sidewall, and the horizontal line that horizontally passes through the endpoint of the tread:

47°≦A≦D.

A preferred way of forming the rib is to satisfy the following condition between the height (SH), which is the maximum height of the tire from the horizontal axis of the tire, the basis point (0), and the height (Dp), which is the height from starting point of the lower profile of the rib to the horizontal axis of the tire:

0.74SH≦Dp≦0.78SH.

A preferred way of forming the rib is to satisfy the following condition between two angles; an interior angle (C), which is the angle between the tangent line that passes through the endpoint of the tread and contacts the lateral profile of the sidewall, and the vertical line that vertically passes through the endpoint of the tread, and an interior angle (B), which is the angle between the lateral profile of the tread and the continued vertical line that vertically passes through the endpoint of the tread:

0°≦B≦C.

A preferred way of forming is to have a recessive circular arc in the radius (Rc), which is the radius of the recessive section which includes the starting point of the lower profile of the ring-shaped rib, of the uniform length in the starting point of the lower profile among the entire lower profile of the ring-shaped rib.

A preferred way of forming the rib is to satisfy the following condition between the radius (Ra), which is the radius of the section of the curved line from the lateral profile of the tread to the upper profile of the rib in order to make the section smoother, the radius (Rd), which is the radius of the imaginary circle such that the tangent of the circle contacts the upper profile of the rib that passes through the endpoint of the tread, the radius (Rc), which is the radius of the recessive section which includes the starting point of the lower profile of the ring-shaped rib, the radius (Re), which is the radius of the imaginary circle that has the perpendicular line coming from the tangent line (Le) that provides interior angle (A) starting at the lower profile of the ring-shaped rib as its diameter:

2 mm≦Ra≦Rd,

3 mm≦Rc≦Re.

Moreover, a preferred way is to have more drainage grooves or more drainage protuberances on the surface of the rib. The drainage grooves or the drainage protuberances are to be in uniform range according to the rib, for example, the range will be 0.5°˜5° along the direction of the circumference of the tire from the continuation line (CS) connecting the center of the endpoint of the sidewall and the center of the sidewall.

Furthermore, when forming the drainage grooves or the drainage protuberances on the surface of the upper profile of the rib, it is preferred that the drainage grooves or the drainage protuberances to have an S-shape or an X-shape, resulting in a better drainage of the tire while driving on a wet road.

When forming the drainage protuberance on the surface of rib, it is preferred that the height of the protuberance is between 1 mm 6 mm, and in the case of the drainage groove, the depth should be between 1 mm 6 mm.

Also, it is preferred that the height of the rib (h) is 0.085˜0.115 times (0.085 TW≦h≦0.115 TW) the width of the tread (TW).

Moreover, there can be more than one drainage groove that goes along the circumference of the tire inside the upper profile of the rib.

Further, the formation of the rib if viewing in the direction of looking down the tread can be configured such that the plane of the free end, including the outmost point of the rib, goes along the circumference of the tire making a form of a sine wave.

As described above, through the configuration of the water-splash control rib, when a heavy load vehicle drives through a puddle of water, there is a possibility that the water will splash in to vehicles going in the same direction or coming from the opposite direction, thus creating a hazard for drivers as well as the pedestrian. With the pneumatic radial tire with water-splash control rib, the hazardous condition can be prevented.

Moreover, with optimizing the position and the shape of the rib, it is possible to prevent accidents caused by belt separation and cracks from the sidewall that the conventional water-splash control tires used. Further, by optimizing the profile of the rib, minimizing the weight increase of installing water-splash control ring-shaped rib is also possible.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will be better understood with reference to the variant embodiments using the drawings, in which the configuration, process, and effectiveness will be described for the pneumatic radial tire with water-splash control.

Here, the embodiments 1 through 4 use 4 layer of belts keyed for heavy duty tires, but it can also be applied to passenger vehicle tires (PC) where 2 layer of belts are used.

Embodiment 1

FIG. 2 and FIG. 3 show that the present embodiment has a center line (CL) through the tire and forms symmetry. Under the tread (TD), which comes in contact with the surface of the road, is the body ply (CC) and 4 belts (1B, 2B, 3B, 4B).

Along the sidewall (20), there is a water-splash control ring-shaped rib (100) installed, optimized for cross-section profile. The upper profile of the rib is positioned above the continuation line which extends the average profile of the outmost belt (4B), and the details follow.

FIG. 3 illustrates that assuming that there are 2 horizontal curved line (Cc, Cb) horizontally moved by short distance (D1, D2) from the continuation curved line starting at the bottom of the tire groove, intersection (Pb) is formed by intersecting with short horizontal curved line (Cc) due to relatively short distanced (D1) and lateral profile (La) of the tread (TD). Moreover, horizontally moved (D2) horizontal curved line (Cb), which is relatively long, intersects with intersection (Pc) which passes through the endpoint (Pa) of the lateral profile (La) of the tread forms a horizontal line (Le) that creates an interior angle (A).

The line connecting the intersections (Pb, Pc) becomes the upper profile (Lb) of the rib (100), and according to the present invention, the upper profile of the rib is always positioned above the average continuation curved line (Ca) which extends to the profile of the outmost belt (4B) of the tread (TD).

In this embodiment, D1 was 5 mm and D2 was 6 mm.

The positioning of the rib in the present invention of the tire with water-splash control is defined in the following manner. For example, FIG. 2 or FIG. 5 shows that the starting point of the lower profile (Pe) of the rib (100) positioned in the lateral profile (Cd) of the sidewall must satisfy the condition which provides for the height (HL) from the starting point to the horizontal axis (HL) of the tire and the highest height (SH):

0.74SH≦Dp≦0.78SH

The tire's height (SH) is defined as the maximum height of the tire from the horizontal axis of the tire.

If the height (Dp) between the starting point (Pe) and horizontal axis (HL) is less than 0.74 SH, the rib's cross-section will unnecessarily increase and thus will increase the weight of the tire and decrease the heat radiation of the tire, and lower the shock absorption of the sidewall and as a result, yielding an uncomfortable ride. On the other hand, if the height (Dp) is higher than 0.78 SH, the thickness of the rib (100) will become thinner resulting in a lower strength of the rib, causing the water-splash control not to function properly.

As for the lateral profile (La) of the tread, which is positioned above the upper profile of the rib (100), is defined according to the following.

FIG. 4 shows that an interior angle (B), which is an angle between the lateral profile of the tread and the continued vertical line that vertically passes through the endpoint of the tread must be smaller than an interior angle (C), which is an angle between the tangent line (Ld) that passes through the endpoint (Pa) of the tread and contacts the lateral profile (Cd) of the sidewall, and the vertical line (Lc) that vertically passes through the endpoint of the tread. If shown as a formula, it will look like this:

0°≦B≦C

If the interior angle (B) becomes less than 0, the tread's lateral strength will drop, and if the interior angle (B) is greater than the interior angle (C), the heat that is created at the end of the belt during driving cannot be effectively radiated.

As shown in FIG. 3 and FIG. 4, the rib (100) of the current embodiment must maintain a condition where an interior angle (A), which is an angle between the tangent line (Le) that passes through the endpoint (Pa) of the tread and contacts the upper profile (Lb) of the ring-shaped rib, and the continued horizontal line that horizontally passes through the endpoint (Pa) of the tread, and an interior angle (D), which is an angle between the tangent line (Ld) that passes through the endpoint (Pa) of the tread and contacts the lateral profile (Cd) of the sidewall, and the horizontal line that horizontally passes through the endpoint of the tread:

47°≦A≦D

If the interior angle (A) is less than 47°, the height of the rib will be too big, thus the heat created at the end of the belts will not be radiated effectively, especially, the heat created by the second belt (2B) and the third belt (3B). However, if the interior angle (A) is greater than the interior angle (D) so that the height of the rib is too small, the capacity of the water-splash control will diminish, making the tire same as with the conventional tire.

As shown in FIG. 3 and FIG. 5, by defining the profile of the rib (100), the following conditions must be satisfied for the radius (Ra), which is the radius of the section of the curved line from the lateral profile of the tread to the upper profile of the rib in order to make the section smoother, the radius (Rd), which is the radius of the imaginary circle such that the tangent of the circle contacts the upper profile of the rib that passes through the endpoint of the tread, the radius (Rc), which is the radius of the recessive section which includes the starting point of the lower profile of the rib, the radius (Re), which is the radius of the imaginary circle that has the perpendicular line coming from the tangent line (Le) that provides interior angle (A) starting at the lower profile of the rib as its diameter:

2 mm≦Ra≦Rd,

3 mm≦Rc≦Re

If the radius (Ra) is less than 2 mm, a crack may be caused due to the concentration of repeated expansion while driving. However, if the radius (Ra) is larger than the radius (Rd), the width of the shoulder part will get thicker, causing inefficient heat radiation at the end of the belt during driving and it can also cause separation, leading to drop in the durability of the tire.

Moreover, if the radius (Rc) is less than 3 mm, there is a possibility of a crack due to the repeated expansion of the sidewall while driving. On the other hand, if the diameter (Rc) is larger than radius (Re), the width of the rib will become thinner, lowering the stiffness of the rib causing ineffective functioning of the water-splash control.

In order to connect the upper profile (Lb) of the rib with the lower profile of the rib by a smooth curved line, it is preferred that the free end of the rib is a form of an arc having a small radius (Rb). Here, the free end of the rib includes the point (F), which is the farthest point of the rib from the center line, such that it is always more protrude than the point (E), which is the farthest point of the sidewall (20) from the center line. In other words, as shown in FIG. 15, the distance between the point (E) of the sidewall and the center line (CL) of the tire is smaller than the point (F) of the above rib and the center line (CL) of the tire.

Following such configuration, it is possible to lower the splash when water is compressed between the surface of the road and the tread.

Embodiment 2

FIG. 6 is a cross-sectional drawing of a different embodiment according to the pneumatic radial tire with ring-shaped water-splash control rib, and FIG. 7 illustrates an enlargement cross-sectional drawing of the. FIG. 8 is a solid figure of FIG. 6 and FIG. 9 is a lateral view of FIG. 6, FIG. 10 is a solid figure confronting FIG. 8, and FIG. 11 is a graphic lateral view of water-splash control tire of FIG. 10.

As shown in the drawings, the tire (1) consists of tread (TD) and sidewall (20), and under the tread (TD), there are layer of belts composed of four belts.

The sidewall (20) has a rib (100) that is protrude outward and the drainage grooves (110) or the drainage protuberances are formed on the surface of the lateral side of the rib along the sidewall (20).

According to this embodiment, the protrusion of the rib is the direction of the tire's lateral direction from a point of the sidewall (20) which is in the same line with the second belt from the layer of belts (12). It is also proper to have the protrusion from the point where there is an intersection between the continuation line of the average profile of the outmost belt and the lateral profile of the sidewall.

The preferred height (h) of the protuberance of the rib (100) is 0.085˜0.115 times the width (TW) of the tread. If the height of the protuberance of the rib (100) is less than 0.085 times the width (TW) of the tread, it will be hard to effectively prevent the water splashing by compressing the tire against the surface of the wet road. On the other hand, if the height of the protuberance of the rib is greater than 0.115 times the width of the tread, there is an unnecessary cost in producing the protuberance of the rib.

The drainage grooves (110) or the drainage protuberances are formed from the outer-end of the sidewall (20) to the lateral surface of the rib; the depth of the drainage groove is between 1 mm˜6 mm.

The depth (t) of the above drainage groove (110) must satisfy the above condition, and if the depth is less than 1 mm, the water drain is not as effective, but oppositely, if the depth is greater than 6 mm, the strength of the rib is lower and thus the water-splash control is not as effective.

It is preferred to have the drainage groove (110) to be in the center of the sidewall (20) and the range should be 0.5°˜5° along the direction of the circumference of the tire from the continuation line (CS) connecting the center of the endpoint (20) of the sidewall and the center of the sidewall and the protrusion be in uniform degree so that the water drainage is effective.

As shown in FIG. 10 and FIG. 11, the rib (100′) can have a totally different form of drainage groove (110′), and according to this formation, the plurality of the drainage grooves (110′) cross over with symmetry with the continuation line (CS) as the basis which connects the sidewall's (20) endpoint and the central part so that regardless of whether the tire rotates forward or backward, the water is easily drained. In this situation, it is preferred that the range (d) between the adjacent drainage groove (110′) or the drainage protuberance to be 0.5˜5°.

Embodiment 3

FIG. 12 is another embodiment of the present invention which shows the cross-sectional view of the tire with water-splash control.

In a preferred aspect, the rib, when viewed from the direction of looking down at the tread, is that the formation of the plane of the free end forms a sine wave which makes for better drainage in the rib.

Embodiment 4

FIG. 13 is another embodiment of the present invention which is a cross-sectional view of the tire with water-splash control and FIG. 14 is a partial enlargement of FIG. 13.

As shown in FIG. 13, the rib in this case has at least one drainage channel (120) that goes along the circumference of the tire which is in the upper profile (Lb) of the rib.

According to this configuration, part of the water that is splashed from the surface of the road will drain backward with the drainage channel (120) along the circumference of the tire, and the rest of the water will drain outward of the tire's sidewall following the surface of the ring-shaped rib, thus resulting in a much improved drainage in the tire.

It is to be understood that the foregoing describes preferred embodiments of the invention and that modifications may be made therein without departing from the spirit or scope of the invention as set forth in the claims. To particularly point out and distinctly claim the subject matter regarded as invention, the following claims conclude this specification.

Claims

1. A pneumatic radial tire with layer of belts deposited under a tread and a ring-shaped water-splash control rib formed on the sidewall, wherein an upper profile of the rib is positioned above a continuation line which extends an average profile of an outmost layer of belt which is divided in to upper and lower profile.

2. A pneumatic radial tire according to claim 1, wherein the rib is characterized in that, an interior angle, which is an angle between a tangent line which passes through a tangent line that touches the upper profile and an endpoint of the tread and a horizontal line that is a horizontally continued line from the endpoint of the tread, and an interior angle, which is an angle between a tangent line which passes through the endpoint of the tread that touches a lateral profile of the sidewall and the horizontal line, is to satisfy the following condition: 47°≦A≦D.

3. A pneumatic radial tire according to claim 2, wherein the rib is characterized in that, a height, which is a maximum height of the tire from the horizontal axis of the tire, and a height, which is a height from a starting point of the lower profile of the rib that touches the lower profile of the rib and the lateral profile of the sidewall to the horizontal axis, is to satisfy the following condition: 0.74SH≦Dp≦0.78SH

4. A pneumatic radial tire according to claim 3, wherein the rib is characterized in that, an interior angle, which is an angle between the tangent line which passes through the tangent line that touches the lateral profile of the sidewall and the endpoint of the tread and a vertical line which is the continuation line from the endpoint of the tread, and an interior angle, which is an angle between the vertical line and the lateral profile of the tread, is to satisfy the following condition: 0°≦B≦C.

5. A pneumatic radial tire according to claim 4, wherein the rib comprising a recess section that has a uniform radius including the starting point of the lower profile which is positioned under the continuation line.

6. A pneumatic radial tire according to claim 5, wherein the rib is characterized in that, a radius, which is a radius between a section of the lateral profile of the sidewall and a curved line connecting the upper profile of the rib, a radius, which is a radius of an imaginary circle that passes through the endpoint of the tread connecting to the upper profile of the rib, a radius, which is a radius of the recess section of the lower profile of the rib, and a radius, which is a radius of an imaginary circle that has a starting point from the lower profile of the rib to the tangent line having a diameter of a perpendicular line through the tangent line, is to satisfy the following condition: 2 mm≦Ra≦Rd; and3 mm≦Rc≦Re.

7. A pneumatic radial tire according to claim 1, wherein the rib comprising drainage grooves or drainage protuberances in the upper profile of the rib.

8. A pneumatic radial tire according to claim 7, wherein the drainage grooves or the drainage protuberances are formed in a uniform range apart from each other on the upper profile of the rib.

9. A pneumatic radial tire according to claim 8, wherein a range is characterized in that, a continuation line which is a line connecting the endpoint of the sidewall and the center of rotation of the tire have an angle of 0.5˜5°.

10. A pneumatic radial tire according to claim 9, wherein a shape of the drainage groove or the drainage protuberance formed on the upper surface of the rib is S-shape or X-shape.

11. A pneumatic radial tire according to claim 10, wherein a height of the drainage protuberance is 1 mm 6 mm from the upper profile of the rib.

12. A pneumatic radial tire according to claim 1, wherein the height of the drainage protuberances is 0.085˜0.115 times the width of the tread (0.085 TW≦h≦0.115 TW).

13. A pneumatic radial tire according to claim 1, wherein the upper profile of the rib comprising at least one channel that goes along the circumference of the tire.

14. A pneumatic radial tire according to claim 1, wherein a plane for a free end of the rib, viewed by looking down at the tread comprising a sine wave configuration along the circumference of said tire.

15. A pneumatic radial tire according to claim 1, wherein the rib is characterized in that, a distance between the center line of the tire to an outmost point of the rib is greater than the distance between the center line to an outmost point of the sidewall in a condition where pressure and weight is applied to the tire.

16. A pneumatic radial tire according to claim 1, wherein the layer of belts comprising either 2 or 4 layer of belts.