Patent Publication Number: US-2020290406-A1

Title: Tire

Description:
TECHNICAL FIELD 
     The present disclosure relates to a tire including fine protrusions formed on its outer surface. 
     BACKGROUND ART 
     Conventionally, fine protrusions are formed on a side portion of a tire to configure a patterned region with contrast. For example, WO 2012/131089 discloses a technology for allowing a tire side portion to have a high contrast with plural protrusions formed in the entirety of a patterned region. 
     SUMMARY OF INVENTION 
     Technical Problem 
     A decorative part of a tire side portion includes a region where protrusions are formed. The protrusions control the reflection of light, thereby allowing this region to have a lower brightness than other regions that directly reflect light. However, merely by allowing such a region where protrusions are formed to have a low brightness in the same manner as a whole, the tire has a limited range of expression of the decorative part where the protrusions are formed. 
     An object of the disclosure is to broaden the range of expression of a decorative part having a region where protrusions are formed in a tire. 
     Solution to Problem 
     A tire according to a first aspect is characterized by including: a decorative part which is formed on an outer surface of the tire and includes a base surface; and a first patterned region in which plural first protrusions protruding from the base surface of the decorative part at a protrusion height of from 0.1 mm to 1.0 mm and intervals of larger than 1.0 mm and 3.0 mm or smaller are formed. 
     According to this configuration, the first patterned region is formed in the decorative part on the outer surface of the tire. Further, in this first patterned region, plural first protrusions, which protrude from the base surface at intervals of larger than 1.0 mm and 3.0 mm or smaller and a protrusion height of from 0.1 mm to 1.0 mm, are formed. By this, a light incident on the first patterned region is attenuated while being repeatedly reflected by opposing side surfaces of the first protrusions, and eventually reflected to the outside. 
     The first patterned region thus has a lower brightness than other regions where no protrusion is formed, but has a higher brightness than a region where protrusions are formed at a higher density (e.g., a region where protrusions are arranged at intervals of 0.5 mm). Therefore, in the tire, the range of expression of the decorative part having the region where protrusions are formed can be broadened. 
     A tire of a second aspect is the tire according to the first aspect, which is characterized in that the first protrusions each are include extensions that extend from a base point in plural directions when viewed from a direction perpendicular to the base surface. 
     According to this configuration, the first protrusions each are include extensions that extend from a base point in plural directions when viewed from a direction perpendicular to the base surface. This allows a light to be reflected at different angles by the side surfaces of the first protrusions, so that concentration of the reflected light is inhibited. By this, the first patterned region is prevented from appearing differently even when it is viewed from different angles. 
     A tire of a third aspect is the tire according to the first or the second aspect, which is characterized by including a second patterned region which is arranged in close proximity to the first patterned region in the decorative part and in which plural second protrusions protruding from the base surface at a protrusion height of from 0.1 mm to 1.0 mm and intervals of from 0.1 mm to 1.0 mm are formed. 
     According to this configuration, in the decorative part on the outer surface of the tire, the second patterned region is arranged in close proximity to the first patterned region. Further, in this second patterned region, plural second protrusions which protrude from the base surface and have an interval of from 0.1 mm to 1.0 mm and a protrusion height of from 0.1 mm to 1.0 mm are formed. By this, the second patterned region having a lower brightness than the first patterned region is arranged in close proximity to the first patterned region; therefore, the range of expression of the decorative part can be broadened as compared to a case where only the first patterned region is formed in the decorative part. 
     A tire of a fourth aspect is the tire according to the third aspect, which is characterized in that the protrusion height of the first protrusions formed in the first patterned region and the protrusion height of the second protrusions formed in the second patterned region are different. 
     According to this configuration, the protrusion height of the first protrusions formed in the first patterned region is different from the protrusion height of the second protrusions formed in the second patterned region. Therefore, as compared to a case where the first protrusions and the second protrusions have the same protrusion height, the appearance of the decorative part is modified, so that the range of expression of the decorative part can be broadened. 
     Advantageous Effects of Invention 
     According to the disclosure, the range of expression of a decorative part having a region where protrusions are formed can be broadened in a tire. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a side view of a tire according to a first embodiment of the disclosure; 
         FIG. 2  is an enlarged side view illustrating a decorative part of the tire according to the first embodiment of the disclosure; 
         FIG. 3  is an enlarged plan view illustrating protrusions that are formed in a medium-brightness region of the decorative part of the tire according to the first embodiment of the disclosure; 
         FIG. 4  is a plan view illustrating the protrusions that are formed in the medium-brightness region of the decorative part of the tire according to the first embodiment of the disclosure; 
         FIG. 5A  is a cross-sectional view illustrating the protrusions that are formed in the medium-brightness and low-brightness regions of the decorative part of the tire according to the first embodiment of the disclosure; 
         FIG. 5B  is a cross-sectional view illustrating the protrusions that are formed in the medium-brightness and low-brightness regions of the decorative part of the tire according to the first embodiment of the disclosure; 
         FIG. 6  is an enlarged plan view illustrating protrusions that are formed in a low-brightness region of the decorative part of the tire according to the first embodiment of the disclosure; 
         FIG. 7  is a plan view illustrating the protrusions that are formed in the medium-brightness region of the decorative part of the tire according to the first embodiment of the disclosure; 
         FIG. 8  is a table showing the results of evaluating the tires of Examples according to the first embodiment of the disclosure and the tires of Comparative Examples; 
         FIG. 9  is an enlarged plan view illustrating protrusions that are formed in a decorative part of a tire according to a second embodiment of the disclosure; 
         FIG. 10  is an enlarged plan view illustrating protrusions that are formed in a decorative part of a tire according to a third embodiment of the disclosure; 
         FIG. 11  is a perspective view illustrating a tire according to a fourth embodiment of the disclosure; 
         FIG. 12  is a side view of a tire according to a fifth embodiment of the disclosure; 
         FIG. 13  is an enlarged side view illustrating a decorative part of the tire according to the fifth embodiment of the disclosure; 
         FIG. 14  is an enlarged plan view illustrating protrusions that are formed in a medium-brightness region of the tire according to the fifth embodiment of the disclosure; 
         FIG. 15A  is a cross-sectional view illustrating protrusions that are formed in a decorative part of a tire according to a sixth embodiment of the disclosure; and 
         FIG. 15B  is another cross-sectional view illustrating the protrusions that are formed in the decorative part of the tire according to the sixth embodiment of the disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
     One example of the tire according to the first embodiment of the disclosure will now be described referring to  FIGS. 1 to 8 . In these drawings, an arrow C indicates the tire circumferential direction, an arrow R indicates the tire radial direction, and an arrow W indicates the tire width direction. 
     As illustrated in  FIG. 1 , decorative parts  14  are formed in a tire side portion  12  of a tire  10 . The decorative parts  14  have a circular-arc shape when viewed from an axial direction of the tire  10 , and are arranged at two positions that are symmetrical to each other about a tire central axis CE. Further, a base surface  30  that is recessed with respect to other region  20 , which is a region of the tire side portion  12  other than the decorative parts  14  and where protrusions and the like are not formed, is formed in each decorative part  14 . This base surface  30  constitutes a bottom surface of each decorative part  14  and, when viewed from the tire circumferential direction, the base surface  30  has a curved surface that forms a convex toward the outer side in the width direction of the tire  10 . In the present embodiment, the base surface  30  is recessed by 0.4 mm with respect to the other region  20 . 
     In each of the decorative parts  14 , a low-brightness region  18  which has a lower brightness than the other region  20  and appears in black, as well as medium-brightness regions  16  which have a lower brightness than the other region  20  but a higher brightness than the low-brightness region  18  and appear in gray, are formed. In other words, the low-brightness region  18  and the medium-brightness regions  16  constitute each decorative part  14 . The medium-brightness regions  16  are one example of a first patterned region, and the low-brightness region  18  is one example of a second patterned region. 
     Moreover, as illustrated in  FIG. 2 , the low-brightness region  18  formed in each decorative part  14  extends along the tire circumferential direction, and the medium-brightness regions  16  are arranged on the respective ends of the low-brightness region  18  in the tire circumferential direction. 
     The low-brightness region  18  and the medium-brightness regions  16  are formed by arranging irregularities on the parts corresponding to the low-brightness region  18  and the medium-brightness regions  16  in a mold used for molding the tire  10 . The low-brightness region  18  and the medium-brightness regions  16  are preferably arranged on the tire radial-direction outer side than a maximum-width position of the tire (a part having the maximum linear distance between the tire side portions) from the standpoint of the visibility of these regions in a state where the tire  10  is mounted on a vehicle. 
     (Low-Brightness Region  18 ) 
     As illustrated in  FIG. 7 , the low-brightness region  18  includes plural first asterisk protrusions  34  and plural second asterisk protrusions  36 , which protrude from the base surface  30 . The first asterisk protrusions  34  and the second asterisk protrusions  36  are alternately arranged in both the tire circumferential direction and the tire radial direction. The first asterisk protrusions  34  and the second asterisk protrusions  36  are examples of the second protrusions. 
     [First Asterisk Protrusions  34 ] 
     As illustrated in  FIG. 6 , when viewed from a direction perpendicular to the base surface  30  (e.g., the direction of the rotation axis of the tire  10 ), the first asterisk protrusions  34  are each constituted by first extensions  35 A- 1  and  35 A- 2 , second extensions  35 B- 1  and  35 B- 2  and third extensions  35 C- 1  and  35 C- 2 , which all extend in different directions from a center O 1  as a base point. These six extensions are hereinafter collectively referred to as “extensions  34 E”. Pairs of one of the extensions  34 E and another extension  34 E (excluding those pairs of extensions extending in the opposite directions from the center O 1 ) each form a linear shape that is bent at the center O 1 . 
     The first extension  35 A- 1  and the first extension  35 A- 2  extend from the center O 1  in the opposite directions from each other, whereby a continuous linear shape is formed by the first extension  35 A- 1  and the first extension  35 A- 2 . The first extension  35 A- 1  extends from the center O 1  on the tire radial-direction outer side, while the first extension  35 A- 2  extends from the center O 1  on the tire radial-direction inner side. The first extension  35 A- 1  and the first extension  35 A- 2  have the same length. The first extension  35 A- 1  and the first extension  35 A- 2  are hereinafter collectively referred to as “first extensions  35 A”. 
     The second extension  35 B- 1  and the second extension  35 B- 2  extend from the center O 1  in the opposite directions from each other, whereby a continuous linear shape is formed by the second extension  35 B- 1  and the second extension  35 B- 2 . The second extension  35 B- 1  and the second extension  35 B- 2  are each inclined with respect to the tire circumferential direction such that the end on one side of the tire circumferential direction (left side in  FIG. 6 ) is positioned on the tire radial-direction outer side than the end on the other side (right side in  FIG. 6 ). 
     The second extension  35 B- 1  extends from the center O 1  on one side of the tire circumferential direction, while the second extension  35 B- 2  extends from the center O 1  on the other side of the tire circumferential direction. The second extension  35 B- 1  is longer than the second extension  35 B- 2 . Further, a tip-side portion of the second extension  35 B- 2  is curved toward the tire radial-direction inner side. The second extension  35 B- 1  and the second extension  35 B- 2  are hereinafter collectively referred to as “second extensions  35 B”. 
     The third extension  35 C- 1  and the third extension  35 C- 2  extend from the center O 1  in the opposite directions from each other, whereby a continuous linear shape is formed by the third extension  35 C- 1  and the third extension  35 C- 2 . The third extension  35 C- 1  and the third extension  35 C- 2  are each inclined with respect to the tire circumferential direction such that the end on one side of the tire circumferential direction (left side in  FIG. 6 ) is positioned on the tire radial-direction inner side than the end on the other side (right side in  FIG. 6 ). 
     The third extension  35 C- 1  extends from the center O 1  on one side of the tire circumferential direction, while the third extension  35 C- 2  extends from the center O 1  on the other side of the tire circumferential direction. The third extension  35 C- 1  is shorter than the third extension  35 C- 2 . The third extension  35 C- 1  and the third extension  35 C- 2  are hereinafter collectively referred to as “third extensions  35 C”. 
     The six extensions  34 E each form an angle of 60° with adjacent extensions  34 E. In other words, the first asterisk protrusions  34  have a shape in which the six extensions  34 E radially extend from the center O 1 . 
     As illustrated in  FIG. 5A , the cross-sections of the extensions  34 E of the first asterisk protrusions  34  in a direction perpendicular to the respective extending direction have a substantially isosceles triangular shape with a flat top surface  34 C. In other words, the first asterisk protrusions  34  each have the top surface  34 C and a pair of side surfaces  34 D. In the present embodiment, the width of the top surface  34 C (W 1  in  FIG. 5A ) is 0.02 mm, and the first asterisk protrusions  34  have an apex angle (D 1  in  FIG. 5A ) of 26[°]. Further, the first asterisk protrusions  34  have a single predetermined height value (H 1  in  FIG. 5A ) of from 0.1 mm to 1.0 mm. When the height of the protrusions (protrusion height) is less than 0.1 mm, it is difficult to mold the protrusions, and there is a risk that the protrusions cannot attenuate an incident light to reduce the brightness to such an extent that makes the protrusions appear in black (this will be described below in detail). Meanwhile, by controlling the height of the protrusions to be 1.0 mm or less, the difference in rigidity between the protrusions and their surrounding parts is made small, so that localized concentration of stress is inhibited. 
     The dimensions of the protrusions in the present embodiment, such as the height and the below-described interval (pitch), can be measured using, for example, ONE-SHOT 3D MEASURING MACROSCOPE VR-3000 Series manufactured by Keyence Corporation. 
     [Second Asterisk Protrusions  36 ] 
     As illustrated in  FIG. 6 , the second asterisk protrusions  36  have the same shape as the first asterisk protrusions  34 . Specifically, when viewed from a direction perpendicular to the base surface  30 , the second asterisk protrusions  36  have a shape obtained by rotating the first asterisk protrusion  34  clockwise by 90[°] about the center O 1  and then inverting the first asterisk protrusion  34  thus rotated by 90[°] about the center O 1 . 
     In the second asterisk protrusions  36 , the parts corresponding to the first extensions  35 A- 1  and  35 A- 2 , the second extensions  35 B- 1  and  35 B- 2 , the third extensions  35 C- 1  and  35 C- 2  and the center O 1  of the first asterisk protrusions  34  are referred to as “first extensions  37 A- 1  and  37 A- 2 ”, “second extensions  37 B- 1  and  37 B- 2 ”, “third extensions  37 C- 1  and  37 C- 2 ” and “center O 2 ”, respectively. These six extensions are hereinafter collectively referred to as “extensions  36 E”. 
     Further, in the second asterisk protrusions  36 , the part corresponding to the top surface  34 C of each first asterisk protrusion  34  is referred to as “top surface  36 C”. Moreover, in the second asterisk protrusions  36 , the parts corresponding to the side surfaces  34 D of each first asterisk protrusion  34  are referred to as “side surfaces  36 D” (see  FIG. 5A ). 
     [Other] 
     As illustrated in  FIGS. 6 and 7 , the first asterisk protrusions  34  and the second asterisk protrusions  36  are alternately arranged in both the tire circumferential direction and the tire radial direction, occupying the entirety of the low-brightness region  18  (see  FIG. 2 ). 
     The tips of the first extensions  35 A- 1  and  35 A- 2  of the first asterisk protrusions  34  are inserted between the second extension  37 B- 2  and the third extension  37 C- 1  and between the second extension  37 B- 1  and the third extension  37 C- 2 , respectively, of the second asterisk protrusion  36  adjacent thereto in the tire radial direction. In addition, the tips of the first extensions  37 A- 1  and  37 A- 2  of the second asterisk protrusions  36  are inserted between the second extension  35 B- 1  and the third extension  35 C- 2  and between the second extension  35 B- 2  and the third extension  35 C- 1 , respectively, of the first asterisk protrusion  34  adjacent thereto in the tire circumferential direction. 
     Further, the tip of the third extension  35 C- 1  of each first asterisk protrusion  34  is connected with the tip of the second extension  37 B- 1  of the second asterisk protrusion  36  arranged on the tire radial-direction outer side of the first asterisk protrusion  34 . By this, a connecting part  34 A is formed. Moreover, the tip of the second extension  35 B- 1  of each first asterisk protrusion  34  is connected with the tip of the third extension  37 C- 1  of the second asterisk protrusion  36  arranged on one side of the first asterisk protrusion  34  in the tire circumferential direction. By this, a connecting part  34 B is formed. 
     In the above-described configuration, the first asterisk protrusions  34  and the second asterisk protrusions  36  are connected in a stepwise manner via the connecting parts  34 A and  34 B from the inner side toward the outer side along the tire radial direction. 
     In the first asterisk protrusions  34  and the second asterisk protrusions  36  that are adjacent to one another in the tire radial direction and the tire circumferential direction, the interval between the center O 1  and the center O 2  (hereinafter, referred to as “interval P 1 ”) is a single predetermined value of from 0.1 mm to 1.0 mm. When the interval P 1  is smaller than 0.1 mm, it is difficult to mold the protrusions. Meanwhile, when the interval P 1  is larger than 1.0 mm, there is a risk that the protrusions cannot attenuate an incident light to reduce the brightness to such an extent that makes the protrusions appear in black (this will be described below in detail). 
     The “low-brightness region  18 ” according to the present embodiment, which appears in black, refers to a region having a brightness L* value of, for example, lower than  10  as measured using a handy-type spectrocolorimeter (NF 333 ) manufactured by Nippon Denshoku Industries Co., Ltd. 
     (Medium-Brightness Region  16 ) 
     As illustrated in  FIG. 4 , each medium-brightness region  16  includes plural first asterisk protrusions  44  and plural second asterisk protrusions  46 , which protrude from the base surface  30 . The first asterisk protrusions  44  and the second asterisk protrusions  46  are alternately arranged in both the tire circumferential direction and the tire radial direction. The first asterisk protrusions  44  and the second asterisk protrusions  46  are examples of the first protrusions. 
     [First Asterisk Protrusions  44 ] 
     With regard to the first asterisk protrusions  44 , those parts different from the first asterisk protrusions  34  (see  FIG. 6 ) of the low-brightness region  18  are mainly described below. 
     As illustrated in  FIG. 3 , when viewed from a direction perpendicular to the base surface  30 , the first asterisk protrusions  44  have the same shape as the first asterisk protrusions  34  of the low-brightness region  18  (see  FIG. 6 ). In the first asterisk protrusions  44 , the parts corresponding to the first extensions  35 A- 1  and  35 A- 2 , the second extensions  35 B- 1  and  35 B- 2 , the third extensions  35 C- 1  and  35 C- 2  and the center O 1  of the first asterisk protrusions  34  are referred to as “first extensions  45 A- 1  and  45 A- 2 ”, “second extensions  45 B- 1  and  45 B- 2 ”, “third extensions  45 C- 1  and  45 C- 2 ” and “center O 3 ”, respectively. These six extensions are hereinafter collectively referred to as “extensions  44 E”. The lengths of the extensions  44 E in their extending directions are those that are obtained by increasing the lengths of the corresponding extensions  34 E of the first asterisk protrusions  34  in their extending directions at the same ratio. 
     As illustrated in  FIG. 5B , the cross-sections of the extensions  44 E of the first asterisk protrusions  44  in a direction perpendicular to the respective extending directions have a substantially isosceles triangular shape with a flat top surface  44 C. In other words, the first asterisk protrusions  44  each have the top surface  44 C and a pair of side surfaces  44 D. In the present embodiment, the width of the top surface  44 C (W 2  in  FIG. 5B ) is 0.02 mm, and the first asterisk protrusions  44  have an apex angle (D 2  in  FIG. 5B ) of 26[°]. Further, the first asterisk protrusions  44  have a single predetermined height value (H 2  in  FIG. 5B ) of from 0.1 mm to 1.0 mm. When the height of these protrusions is less than0.1 mm, it is difficult to mold the protrusions, and there is a risk that the protrusions cannot attenuate an incident light to reduce the brightness to such an extent that makes the protrusions appear in gray (this will be described below in detail). Meanwhile, by controlling the height of the protrusions to be 1.0 mm or less, the difference in rigidity between the protrusions and their surrounding parts is made small, so that localized concentration of stress is inhibited. 
     [Second Asterisk Protrusions  46 ] 
     As illustrated in  FIG. 3 , the second asterisk protrusions  46  have the same shape as the first asterisk protrusions  44 . Specifically, when viewed from a direction perpendicular to the base surface  30 , the second asterisk protrusions  46  have a shape obtained by rotating the first asterisk protrusion  44  clockwise by 90[°] about the center O 3  and then inverting the first asterisk protrusion  44  thus rotated by 90[°] about the center O 3 . 
     In the second asterisk protrusions  46 , the parts corresponding to the first extensions  45 A- 1  and  45 A- 2 , the second extensions  45 B- 1  and  45 B- 2 , the third extensions  45 C- 1  and  45 C- 2  and the center O 3  of the first asterisk protrusions  44  are referred to as “first extensions  47 A- 1  and  47 A- 2 ”, “second extensions  47 B- 1  and  47 B- 2 ”, “third extensions  47 C- 1  and  47 C- 2 ” and “center O 4 ”, respectively. These six extensions are hereinafter collectively referred to as “extensions  46 E”. 
     Further, in the second asterisk protrusions  46 , the part corresponding to the top surface  44 C of each first asterisk protrusion  44  is referred to as “top surface  46 C”. 
     Moreover, in the second asterisk protrusions  46 , the parts corresponding to the side surfaces  44 D of each first asterisk protrusion  44  are referred to as “side surfaces  46 D” (see  FIG. 5B ). 
     [Other] 
     As illustrated in  FIG. 3 , the first asterisk protrusions  44  and the second asterisk protrusions  46  are alternately arranged in both the tire circumferential direction and the tire radial direction, occupying the entirety of each medium-brightness region  16  (see  FIG. 2 ). 
     The tips of the first extensions  45 A- 1  and  45 A- 2  of the first asterisk protrusions  44  are inserted between the second extension  47 B- 2  and the third extension  47 C- 1  and between the second extension  47 B- 1  and the third extension  47 C- 2 , respectively, of the second asterisk protrusion  46  adjacent thereto in the tire radial direction. In addition, the tips of the first extensions  47 A- 1  and  47 A- 2  of the second asterisk protrusions  46  are inserted between the second extension  45 B- 1  and the third extension  45 C- 2  and between the second extension  45 B- 2  and the third extension  45 C- 1 , respectively, of the first asterisk protrusion  44  adjacent thereto in the tire circumferential direction. 
     Further, the tip of the third extension  45 C- 1  of each first asterisk protrusion  44  is connected with the tip of the second extension  47 B- 1  of the second asterisk protrusion  46  arranged on the tire radial-direction outer side of the first asterisk protrusion  44 . By this, a connecting part  44 A is formed. Moreover, the tip of the second extension  45 B- 1  of each first asterisk protrusion  44  is connected with the tip of the third extension  47 C- 1  of the second asterisk protrusion  46  arranged on one side of the first asterisk protrusion  44  in the tire circumferential direction. By this, a connecting part  44 B is formed. 
     In the above-described configuration, the first asterisk protrusions  44  and the second asterisk protrusions  46  are connected in a stepwise manner via the connecting parts  44 A and  44 B from the inner side toward the outer side along the tire radial direction. 
     In the first asterisk protrusions  44  and the second asterisk protrusions  46  that are adjacent to one another in the tire radial direction and the tire circumferential direction, the interval between the center O 3  and the center O 4  (hereinafter, referred to as “interval P 2 ”) is a single predetermined value of larger than 1.0 mm and 3.0 mm or smaller. When the interval P 2  is 1.0 mm or smaller, there is risk that an incident light may be excessively attenuated and the brightness may thereby be reduced to such an extent that makes the protrusions appear in black (this will be described below in detail). Meanwhile, when the interval P 2  is larger than 3.0 mm, there is a risk that the protrusions cannot attenuate an incident light to reduce the brightness to such an extent that makes the protrusions appear in gray (this will be described below in detail). 
     The “medium-brightness region  16 ” according to the present embodiment, which appears in gray, refers to a region having a brightness L* value of, for example, from 10 to 20 as measured using a handy-type spectrocolorimeter (NF333) manufactured by Nippon Denshoku Industries Co., Ltd. Further, in the tire side portion  12 , the regions  20  other than the decorative parts  14  (regions where not protrusion is formed) are regions having a brightness L* value of, for example, higher than  20  as measured using a handy-type spectrocolorimeter (NF333) manufactured by Nippon Denshoku Industries Co., Ltd. In other words, the “medium-brightness region  16 ” appearing in gray is a region having a relatively moderate brightness on the outer surface of the tire  10 . 
     (Actions and Effects) 
     Next, the actions and effects of the tire according to the present embodiment will be described. 
     In the low-brightness regions  18  of the decorative parts  14  of the tire side portion  12 , a light incident on the first asterisk protrusions  34  and the second asterisk protrusions  36  that are formed in the low-brightness regions  18  collides with the side surfaces  34 D and  36 D illustrated in  FIG. 5A . This incident light is attenuated while being repeatedly reflected between opposing side surfaces  34 D and  36 D, and eventually reflected to the outside. 
     In the medium-brightness regions  16  of the decorative parts  14  of the tire side portion  12 , a light incident on the first asterisk protrusions  44  and the second asterisk protrusions  46  that are formed in the medium brightness regions  16  collides with the side surfaces  44 D and  46 D illustrated in  FIG. 5B . This incident light is attenuated while being repeatedly reflected between opposing side surfaces  44 D and  46 D, and eventually reflected to the outside. 
     Further, in the other regions  20  of the tire side portion  12  where no protrusion is formed, a light incident thereon is reflected to the outside by the outer surface constituting the respective other regions  20 . 
     The interval P 1  between the first asterisk protrusions  34  and the second asterisk protrusions  36  that are formed in the low-brightness regions  18  is a single predetermined value of from 0.1 mm to 1.0 mm. Meanwhile, the interval P 1  between the first asterisk protrusions  44  and the second asterisk protrusions  46  that are formed in the medium-brightness regions  16  is a single predetermined value of larger than 1.0 mm and 3.0 mm or smaller. In other words, the density of the protrusions formed in the medium-brightness regions  16  is set to be lower than the density of the protrusions formed in the low-brightness regions  18 . 
     Moreover, since the protrusions have the same apex angle, the ratio of the base surface  30  per unit area in the medium-brightness regions  16  is higher than the ratio of the base surface  30  per unit area in the low-brightness regions  18 . 
     As a result, the amount of the light reflected to the outside by the medium-brightness regions  16  is greater than the amount of the light reflected to the outside by the low-brightness regions  18 . In addition, the amount of the light reflected to the outside by the medium-brightness regions  16  is smaller than the amount of the light reflected to the outside by the other regions  20  where no protrusion is formed. In other words, the brightness L* increases in the order of the low-brightness regions  18 , the medium-brightness regions  16 , and the other regions  20 . 
     Therefore, the low-brightness regions  18  appear more blackish relative to other regions, the other regions  20  appear more whitish relative to other regions, and the medium-brightness regions  16  appear more grayish relative to other regions. 
     In this manner, by controlling the interval P 2  between the first asterisk protrusions  44  and the second asterisk protrusions  46  to be larger than 1.0 mm and 3.0 mm or smaller, the medium-brightness regions  16  which have a lower brightness than the other regions  20  but a higher brightness than the low-brightness regions  18  and appear in gray are formed. Consequently, in the tire  10 , the range of the expression of the decorative parts  14  including regions where protrusions are formed can be broadened (variations of the method therefor can be increased). 
     The extensions  44 E of each first asterisk protrusion  44  extend in different directions, and the extensions  46 E of each second asterisk protrusion  46  also extend in different directions. By this, the medium-brightness regions  16  can be prevented from appearing differently even when the medium-brightness regions  16  are viewed from different angles. The same effect is exerted also for the low-medium regions  18 . 
     In addition, the first asterisk protrusions  44  formed in the medium-brightness regions  16  are each constituted by six extensions  44 E that extend in different directions and are connected at the center O 3 , and the second asterisk protrusions  46  are each constituted by six extensions  46 E that extend in different directions and are connected at the center O 4 . Therefore, the first asterisk protrusions  44  and the second asterisk protrusions  46  are unlikely to collapse, and the durability of each of the first asterisk protrusions  44  and the second asterisk protrusions  46  can be improved. The same effect is exerted also for the first asterisk protrusions  34  and the second asterisk protrusions  36 . 
     Further, the low-brightness regions  18  are formed in close proximity to the medium-brightness regions  16 . As a result, the low-brightness regions  18  appearing more blackish relative to the other regions  20 , the medium-brightness regions  16  appearing more grayish relative to the other regions  20 , and the other regions  20  appearing more whitish relative to the low-brightness regions  18  are arranged in series. Therefore, a gradual change in the brightness L* (gradation effect) can be expressed. 
     Moreover, the first asterisk protrusions  44  and the second asterisk protrusions  46  are connected in a stepwise manner via the connecting parts  44 A and  44 B. This allows the first asterisk protrusions  44  and the second asterisk protrusions  46  to support with one another via the connecting parts  44 A and  44 B, whereby collapse of the first asterisk protrusions  44  and the second asterisk protrusions  46  is inhibited, and the durability can be improved. 
     (Evaluation) 
     In order to verify the effects of the disclosure, tires of Examples 1 to 6 to which the disclosure was applied and tires of Comparative Examples 1 and 2 were prepared, and the below-described tests  1  and  2  were performed. 
     [Evaluation Tires] 
     As test tires, tires all having a size of 205/55R16 and a cross-sectional height SH of 114 mm were used. 
     The tires of Comparative Examples 1 to 6 and Comparative Examples 1 and 2 all had the same structure as the tire according to the first embodiment of the disclosure. However, the interval P 2  and the protrusion height H 2  of the first asterisk protrusions  44  and the second asterisk protrusions  46  formed in the medium-brightness regions  16  as well as the brightness L* value of the medium-brightness regions  16  varied as shown in the table of  FIG. 8 . In addition, the interval P 1  and the protrusion height H 1  of the first asterisk protrusions  34  and the second asterisk protrusions  36  formed in the low-brightness regions  18  as well as the brightness L* value of the low-brightness regions  18  varied as shown in the table of  FIG. 8 . 
     It is noted here that other regions where no protrusion was formed had a brightness L* value of  24 . 
     [Evaluation Method and Evaluation Content] 
     The test tires were each mounted on a vehicle and arranged such that a pair of the decorative parts  14  was positioned along the vertical direction. In an outdoor setting on a sunny day, twenty observers visually observed and evaluated the decorative parts of each test tire from plural directions. 
     As for the evaluation content, it was evaluated whether or not the medium-brightness regions appeared to have a higher brightness than the low-brightness regions and a lower brightness than other regions where no protrusion was formed. An evaluation of “A” was given when the number of the observers who evaluated the medium-brightness regions to be distinguishable as described above was  18  or more; an evaluation of “B” was given when the number of such observers was from  10  to  17 ; or an evaluation of “C” was given when the number of such observers was  9  or less. 
     [Evaluation Results] 
     As shown in the table of  FIG. 8 , the tires of Examples  1  to  6  to which the disclosure was applied all had an evaluation result of “A” or “B”. On the other hand, the tires of Comparative Examples 1 and 2 both had an evaluation result of “C”. As seen from these evaluation results, the range of the expression of the decorative parts  14  was broader in the tires of Examples 1 to 6 than in the tires of Comparative Examples 1 and 2. 
     Second Embodiment 
     Next, a tire  110  according to the second embodiment of the disclosure will be described referring to  FIG. 9 . With regard to the tire  110  of the second embodiment, those parts different from the tire  10  of the first embodiment are mainly described. 
     As illustrated in  FIG. 9 , protrusions  134  formed in low-brightness regions  118  of the tire  110  each have an extension  135 A which extends on the other side of the tire circumferential direction from a center O 6  as a base point. Further, the protrusions  134  each have an extension  135 B which extends from the center O 6  on the other side of the tire circumferential direction toward the tire radial-direction outer side, and an extension  135 C which extends from the center O 6  on the other side of the tire circumferential direction toward the tire radial-direction inner side. In the protrusions  134  that are adjacent to one another in the tire radial direction and the tire circumferential direction, the interval between one center O 6  and another center O 6  (hereinafter, referred to as “interval P 11 ”) is a single predetermined value of from 0.1 mm to 1.0 mm. The low-brightness regions  118  are one example of the second patterned region, and the protrusions  134  are one example of the second protrusions. 
     As illustrated in  FIG. 9 , protrusions  144  formed in medium-brightness regions  116  of the tire  110  each have an extension  145 A which extends on the other side of the tire circumferential direction from a center O 7  as a base point. Further, the protrusions  144  each have an extension  145 B which extends from the center O 7  on the other side of the tire circumferential direction toward the tire radial-direction outer side, and an extension  145 C which extends from the center O 7  on the other side of the tire circumferential direction toward the tire radial-direction inner side. In the protrusions  144  that are adjacent to one another in the tire radial direction and the tire circumferential direction, the interval between one center O 7  and another center O 7  (hereinafter, referred to as “interval P 12 ”) is a single predetermined value of larger than 1.0 mm and 3.0 mm or smaller. The medium-brightness regions  116  are one example of the first patterned region, and the protrusions  144  are one example of the first protrusions. 
     The effects of the second embodiment are the same as those of the first embodiment, except that the effect exerted by connecting the protrusions. 
     Third Embodiment 
     Next, a tire  210  according to the third embodiment of the disclosure will be described referring to  FIG. 10 . With regard to the tire  210  of the third embodiment, those parts different from the tire  10  of the first embodiment are mainly described. 
     As illustrated in  FIG. 10 , protrusions  234  formed in low-brightness regions  218  of the tire  210  are each a hexagonal pyramid having a regular hexagonal bottom surface, and a top surface  234 C oriented to the protruding direction is formed on a protruding end of each protrusion  234 . In the protrusions  234  that are adjacent to one another in the tire radial direction and the tire circumferential direction, the interval between the center of one protrusion  234  and the center of another protrusion  234  (hereinafter, referred to as “interval P 21 ”) is a single predetermined value of from 0.1 mm to 1.0 mm. The low-brightness regions  218  are one example of the second patterned region, and the protrusions  234  are one example of the second protrusions. 
     Further, as illustrated in  FIG. 10 , protrusions  244  formed in medium-brightness regions  216  of the tire  210  are each a hexagonal pyramid having a regular hexagonal bottom surface, and a top surface  244 C oriented to the protruding direction is formed on a protruding end of each protrusion  244 . In the protrusions  244  that are adjacent to one another in the tire radial direction and the tire circumferential direction, the interval between the center of one protrusion  244  and the center of another protrusion  244  (hereinafter, referred to as “interval P 22 ”) is a single predetermined value of larger than 1.0 mm and 3.0 mm or smaller. The medium-brightness regions  216  are one example of the first patterned region, and the protrusions  244  are one example of the first protrusions. 
     The effects of the third embodiment are the same as those of the first embodiment, except that the effect exerted by connecting the protrusions. 
     Fourth Embodiment 
     Next, a tire  310  according to the fourth embodiment of the disclosure will be described referring to  FIG. 11 . With regard to the tire  310  of the fourth embodiment, those parts different from the tire  10  of the first embodiment are mainly described. 
     A decorative part  314  of the tire  310  is formed on a tread  330  on the tire radial-direction outer side of the tire  310 . Specifically, on the tread  330  of the tire  310 , plural circumferential grooves  332  extending along the tire circumferential direction are formed apart from one another in the tire width direction (arrow W in  FIG. 11 ). The decorative part  314  is formed in one of the circumferential grooves  332  that is on the center side in the tire width direction. Further, in the decorative part  314 , only a medium-brightness region  316  is formed, and this medium-brightness region  316  includes plural first asterisk protrusions  44  and plural second asterisk protrusions  46  (see  FIG. 3 ), which protrude from a base surface  332 A constituting the bottom surface of the circumferential groove  332 . The medium-brightness region  316  is one example of the first patterned region. 
     The effects of the fourth embodiment are the same as those of the first embodiment that are exerted by allowing the tire  10  to have only the medium-brightness region  16 . 
     Fifth Embodiment 
     Next, a tire  410  according to the fifth embodiment of the disclosure will be described referring to  FIGS. 12 to 14 . With regard to the tire  410  of the fifth embodiment, those parts different from the tire  10  of the first embodiment are mainly described. 
     As illustrated in  FIGS. 12 and 13 , medium-brightness regions  416  of the tire  410  each include: a first medium-brightness region  446 , which is formed on the respective end portions of the decorative part  14  in the tire circumferential direction; and a second medium-brightness region  466 , which is formed between the first medium-brightness region  446  and the low-brightness region  18 . 
     As illustrated in  FIG. 14 , the first medium-brightness region  446  includes plural first asterisk protrusions  44  and plural second asterisk protrusions  46 , which protrude from the base surface  30 . In the first asterisk protrusions  44  and the second asterisk protrusions  46  that are adjacent to one another in the tire radial direction and the tire circumferential direction, the interval P 31  between the center O 3  and the center O 4  is a single predetermined value of larger than 1.0 mm and 3.0 mm or smaller. The first medium-brightness region  446  and the second medium-brightness region  466  are examples of the first patterned region. 
     Further, as illustrated in  FIG. 14 , the second medium-brightness region  466  includes plural first asterisk protrusions  44  and plural second asterisk protrusions  46 , which protrude from the base surface  30 . In the first asterisk protrusions  44  and the second asterisk protrusions  46  that are adjacent to one another in the tire radial direction and the tire circumferential direction, the interval P 32  between the center O 3  and the center O 4  is a single predetermined value that is smaller than the above-described interval P 31  in a range of larger than 1.0 mm and 3.0 mm or smaller. 
     In this configuration, the brightness L* decreases in a stepwise manner in the order of the first medium-brightness region  446 , the second medium-brightness region  466 , and the low-brightness region  18 . By this, a gradual change in the brightness L* (gradation effect) can be effectively expressed. 
     Other effects of the fifth embodiment are the same as those of the first embodiment. 
     Sixth Embodiment 
     Next, a tire  510  according to the sixth embodiment of the disclosure will be described referring to  FIG. 15 . With regard to the tire  510  of the sixth embodiment, those parts different from the tire  10  of the first embodiment are mainly described. 
     The protrusion height H 31  of the first asterisk protrusions  34  and the second asterisk protrusions  36  that are formed in the low-brightness regions  18  of the tire  510  is a single predetermined value of from 0.1 mm to 1.0 mm (see  FIG. 15A ). 
     Further, the protrusion height H 32  of the first asterisk protrusions  44  and the second asterisk protrusions  46  that are formed in the medium-brightness regions  16  of the tire  510  is also a single value of from 0.1 mm to 1.0 mm but is different from the value of the above-described protrusion height H 31  (see  FIG. 15B ). 
     In this manner, by controlling the protrusion height H 31  of the protrusions formed in the low-brightness regions  18  and the protrusion height H 32  of the protrusions formed in the medium-brightness regions  16  to be different from each other, the appearance of the decorative parts  14  is modified as compared to a case where the protrusion height H 31  and the protrusion height H 32  are the same, so that the range of expression of the decorative parts  14  can be broadened. 
     Thus far, the disclosure has been described in detail referring to specific embodiments; however, the disclosure is not restricted to the above-described embodiments, and it is apparent to those of ordinary skill in the art that various other embodiments are feasible within the scope of the disclosure. For instance, in the first embodiment, the first asterisk protrusions  34  and  44  and the second asterisk protrusions  36  and  46  have an apex angle (D 1  in  FIG. 7 ) of 26[°]; however, these protrusions may have another apex angle. An increase in the apex angle D 1  leads to an increase in the ratio of the light that is reflected by the side surfaces  34 D,  44 D,  36 D and  46 D and returns back to the incident direction, as a result of which the brightness L* is relatively increased. 
     The disclosure of Japanese Patent Application No. 2017-236466 filed on Dec. 8, 2017, is hereby incorporated by reference in its entirety. 
     All the documents, patent applications and technical standards that are described in the present specification are hereby incorporated by reference to the same extent as if each individual document, patent application or technical standard is concretely and individually described to be incorporated by reference. 
     DESCRIPTION OF SYMBOLS 
       10 : tire,  14 : decorative part,  16 : medium-brightness region (one example of first patterned region),  18 : low-brightness region (one example of second patterned region),  30 : base surface,  34 : first asterisk protrusion (one example of second protrusion),  36 : second asterisk protrusion (one example of second protrusion),  36 E: extension,  44 : first asterisk protrusion (one example of first protrusion),  46 : second asterisk protrusion (one example of first protrusion),  46 E: extension,  110 : tire,  116 : medium-brightness region (one example of first patterned region),  118 : low-brightness region (one example of second patterned region),  134 : protrusion (one example of second protrusion),  135 A: extension,  135 B: extension,  135 C: extension,  144 : protrusion (one example of first protrusion),  145 A: extension,  145 B: extension,  145 C: extension,  210 : tire,  216 : medium-brightness region (one example of first patterned region),  218 : low-brightness region (one example of second patterned region),  234 : protrusion (one example of second protrusion),  244 : protrusion (one example of first protrusion),  310 : tire,  314 : decorative part,  316 : medium-brightness region (one example of first patterned region),  332 A: base surface,  410 : tire,  416 : medium-brightness region (one example of first patterned region),  446 : first medium-brightness region (one example of first patterned region),  466 : second medium-brightness region (one example of first patterned region),  510 : tire