Patent Publication Number: US-2022229002-A1

Title: Tire electrical resistance measurement device and electrical resistance probe

Description:
TECHNICAL FIELD 
     The present invention relates to a tire electric resistance measurement device and an electric resistance probe. 
     BACKGROUND ART 
     In general, a vehicle, such as an automobile, is designed such that, in a case where a body is charged, electric charge escapes into the ground through a tire. 
     Accordingly, to secure that electric charge can stably escape into the ground, in a period from when a step, such as vulcanization molding of the tire, ends until shipment, there is a case where an inspection step of inspecting an electric resistance between an inner peripheral portion and a tread part of the tire is performed. In inspecting the electric resistance of the tire, an inner side probe is brought into contact with the inner peripheral portion of the tire, and an outer side probe is brought into contact with the tread part. 
     For example, PTL 1 discloses a configuration in which an outer side probe capable of being brought into contact with a tread part of a tire is curvedly deformable along the shape of the tire from a central portion to a shoulder portion of the tread part in a width direction of the tire. In this configuration, the outer side probe is made of a linear electric conductor that stretches between an end portion of a longitudinal frame and an end portion of a transverse frame. In an outer peripheral surface of the tire, a low electric resistance portion made of a material having low electric resistance is exposed in a part of the tire in the width direction. In PTL 1, the outer side probe made of the linear electric conductor is brought into contact with the outer peripheral surface of the tire, whereby the outer side probe is brought into contact with the low electric resistance portion. 
     CITATION LIST 
     Patent Literature 
     
         
         [PTL 1] Japanese Patent No. 5943810 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     In an inspection step of measuring electric resistance as in PTL 1 described above, the tire is often inspected in a single tire state in which the tire is not mounted on a wheel and is not filled with air. In a case of inspecting the single tire in this way, a part of the tread part of the tire may be dented to the inside in a radial direction of the tire and a dent may be formed. However, the electric conductor of the outer side probe disclosed in PTL 1 cannot enter the dent. For this reason, in a case where the low electric resistance portion is disposed in the dent of the tread part of the tire, there is a possibility that the electric conductor of the outer side probe is not brought into contact with the low electric resistance portion, and the electric resistance of the tire cannot be correctly measured. 
     An object of the invention is to provide a tire electric resistance measurement device and an electric resistance probe capable of improving reliability in electric resistance measurement of a tire. 
     Solution to Problem 
     According to a first aspect of the invention, there is provided a tire electric resistance measurement device including an inner side probe and an outer side probe. The inner side probe is disposed on an inner periphery side of a tire and is capable of being brought into contact with an inner peripheral portion of the tire. The outer side probe is disposed on an outer periphery side of the tire and is capable of being brought into contact with a tread part of the tire by relatively moving in a radial direction of the tire with respect to the tire. The outer side probe extends in a width direction of the tire and is deformable following the radial direction corresponding to an undulating shape of the tread part in the width direction. The outer side probe has electric conductivity in at least a contact surface of the deformable portion with the tread part. 
     According to such a configuration, the outer side probe is deformable following the radial direction corresponding to the undulating shape of the tread part in the width direction of the tire. With this, in a case where the outer peripheral surface is dented to an inside in the radial direction of the tire in a part of the tire in the width direction, the outer side probe enters the portion dented to the inside in the radial direction. Then, the contact surface of the outer side probe having electric conductivity is brought into contact with the outer peripheral surface of the tire even in the portion dented to the inside in the radial direction of the tire. Therefore, even in a case where a low electric resistance portion is positioned in the portion dented to the inside in the radial direction of the tire, the outer side probe is brought into contact with the low electric resistance portion, whereby it is possible to improve reliability in electric resistance measurement of the tire. 
     According to a second aspect of the invention, the tire electric resistance measurement device may be configured such that the outer side probe of the first aspect enters a dent more dented to an inside in the radial direction than a maximum outer diameter portion of the tire in an intermediate portion of the tire in the width direction in a case where the outer side probe is brought into contact with the tread part of the tire by relatively moving in the radial direction of the tire with respect to the tire. 
     With this, the deformable portion enters the dent more dented to the inside in the radial direction than the maximum outer diameter portion of the tire in the intermediate portion of the tire in the width direction. Therefore, even in a case where a low electric resistance portion is positioned in the portion dented to the inside in the radial direction of the tire, it is possible to bring the outer side probe into contact with the low electric resistance portion. 
     According to a third aspect of the invention, the tire electric resistance measurement device may further include a support member that has rigidity higher than the outer side probe of the first aspect, extends in the width direction outside the tire in the radial direction with respect to the outer side probe, and supports the outer side probe. 
     With this, when the outer side probe is brought into contact with the tread part of the tire and is deformed in the radial direction corresponding to the undulating shape of the tread part in the width direction, the support member firmly supports the outer side probe on an outside in the radial direction. With this, it is possible to make the outer side probe enter the dent more dented to the inside in the radial direction than the maximum outer diameter portion of the tire. 
     According to a fourth aspect of the invention, the tire electric resistance measurement device may be configured such that the outer side probe of the first aspect includes a driven displaceable portion and a pressing portion. The driven displaceable portion is displaced to an outside in the radial direction corresponding to the undulating shape of the tread part of the tire in a case where the driven displaceable portion is brought into contact with the tread part of the tire by relatively moving in the radial direction of the tire with respect to the tire. The pressing portion presses the driven displaceable portion to an inside in the radial direction of the tire. 
     With this, in a case where the driven displaceable portion is brought into contact with the tread part of the tire by relatively moving in the radial direction with respect to the tire, the driven displaceable portion is displaced to be press-fitted to the outside in the radial direction corresponding to the undulating shape of the tread part of the tire. Since the driven displaceable portion is pressed to the inside in the radial direction of the tire by the pressing portion, the driven displaceable portion enters the dent more dented to the inside in the radial direction than the maximum outer diameter portion of the tire. Therefore, even in a case where a low electric resistance portion is positioned in the portion dented to the inside in the radial direction of the tire, it is possible to bring the outer side probe into contact with the low electric resistance portion. 
     According to a fifth aspect of the invention, the tire electric resistance measurement device may be configured such that the driven displaceable portion of the fourth aspect is a band-shaped member that extends in the width direction and has flexibility and electric conductivity. 
     With this, the driven displaceable portion made of the band-shaped member that extends in the width direction of the tire and has flexibility and electric conductivity enters the dent more dented to the inside in the radial direction than the maximum outer diameter portion of the tire. Therefore, even in a case where a low electric resistance portion is positioned in the portion dented to the inside in the radial direction of the tire, it is possible to bring the outer side probe into contact with the low electric resistance portion. 
     According to a sixth aspect of the invention, the tire electric resistance measurement device may be configured such that the driven displaceable portion of the fourth aspect is a plurality of advance/retreat members that are provided at intervals in the width direction and are provided advanceable and retreatable in the radial direction. 
     With this, each of the advance/retreat members configuring the driven displaceable portion is displaced to be press-fitted to the outside in the radial direction corresponding to the undulating shape of the tread part of the tire in a case where each of the advance/retreat members is brought into contact with the tread part of the tire by relatively moving in the radial direction with respect to the tire. Since a plurality of advance/retreat members are pressed to the inside in the radial direction of the tire by the pressing portion, a plurality of advance/retreat members enter the dent more dented to the inside in the radial direction than the maximum outer diameter portion of the tire. Therefore, even in a case where a low electric resistance portion is positioned in the portion dented to the inside in the radial direction of the tire, it is possible to bring the outer side probe into contact with the low electric resistance portion. 
     According to a seventh aspect of the invention, the tire electric resistance measurement device may be configured such that the pressing portion of the fourth aspect is formed to be compressible by being elastically deformed toward the outside in the radial direction corresponding to the undulating shape of the tread part of the tire in a case where the pressing portion is brought into contact with the tread part of the tire by relatively moving in the radial direction of the tire with respect to the tire. 
     With this, since the pressing portion is elastically deformed toward the outside in the radial direction and compressed, and exerts pressing force toward the inside in the radial direction, the driven displaceable portion that is displaced to be press-fitted to the outside in the radial direction corresponding to the undulating shape of the tread part of the tire is pressed to the inside in the radial direction of the tire by the pressing force of the pressing portion. With this, it is possible to make the driven displaceable portion enter the dent more dented to the inside in the radial direction than the maximum outer diameter portion of the tire. 
     According to an eighth aspect of the invention, the outer side probe of the first aspect is elastically deformable toward an outside in the radial direction corresponding to the undulating shape of the tread part of the tire in a case where the outer side probe is brought into contact with the tread part of the tire by relatively moving in the radial direction of the tire with respect to the tire, and has electric conductivity. 
     With this, since the outer side probe is elastically deformable and has electric conductivity, in a case where a part of the tire in the width direction is dented to the inside in the radial direction of the tire, the outer side probe enters the portion dented to the inside in the radial direction. Then, the outer side probe is brought into contact with the outer peripheral surface of the tire over the entire tire in the width direction. Therefore, even in a case where a low electric resistance portion is positioned in the portion dented to the inside in the radial direction of the tire, it is possible to bring the outer side probe into contact with the low electric resistance portion to inspect the electric resistance of the tire. Furthermore, since the outer side probe has electric conductivity, it is possible to efficiently perform manufacturing or the like of the outer side probe compared to a case where only a contact surface has electric conductivity. 
     According to a ninth aspect of the invention, there is provided an electric resistance probe that extends in a width direction of a tire, is deformable following a radial direction of the tire corresponding to an undulating shape of the tire in the width direction in a case where the electric resistance probe is brought into contact with the tire by relatively moving in the radial direction of the tire with respect to the tire, and has electric conductivity in at least a contact surface with the tire. 
     In a case where such an electric resistance probe is applied to at least one of the outer side probe and the inner side probe of the tire electric resistance measurement device of any one of the first to eighth aspects, when the electric resistance probe is brought into contact with the tire, it is possible to deform the electric resistance probe following the radial direction of the tire corresponding to the undulating shape of the tire. For this reason, even though there is an undulating shape, for example, it is possible to bring the electric resistance probe into contact with a low electric resistance portion exposed in a tread part or an electric conduction portion exposed in a bead portion. Therefore, it is possible to improve reliability in electric resistance measurement of a tire. 
     Advantageous Effects of Invention 
     With the tire electric resistance measurement device and the electric resistance probe described above, it is possible to improve reliability in electric resistance measurement of a tire. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a configuration diagram showing the schematic configuration of an electric resistance measurement device in a first embodiment of the invention. 
         FIG. 2  is a partial sectional view showing a main part of the electric resistance measurement device. 
         FIG. 3  is a plan view showing disposition of an outer side probe and an inner side probe of the electric resistance measurement device. 
         FIG. 4  is a side view showing the outer side probe of the electric resistance measurement device. 
         FIG. 5  is a diagram showing the outer side probe of the electric resistance measurement device and is a sectional view taken along an arrow A-A of  FIG. 4 . 
         FIG. 6  is a sectional view showing a state in which the outer side probe of the electric resistance measurement device is pressed to an outer peripheral surface of a tire. 
         FIG. 7  is a sectional view showing a state in which an outer side probe of an electric resistance measurement device in a modification example of the first embodiment of the invention is pressed to a tread part of the tire. 
         FIG. 8  is a sectional view showing a state in which an outer side probe of an electric resistance measurement device in a second embodiment of the invention is pressed to a tread part of a tire. 
         FIG. 9  is a sectional view showing a state in which an outer side probe of an electric resistance measurement device in a third embodiment of the invention is pressed to a tread part of a tire. 
         FIG. 10  is a diagram showing an inner side probe in a modification example of an embodiment of the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
       FIG. 1  is a configuration diagram showing the schematic configuration of an electric resistance measurement device in a first embodiment of the invention. 
     As shown in  FIG. 1 , an electric resistance measurement device  1  in the first embodiment is disposed on an inspection line (not shown) of a vulcanized tire T. The electric resistance measurement device  1  includes a roller conveyor  2  and a probe unit  6 . 
     The roller conveyor  2  transfers the tire T. The roller conveyor  2  includes a plurality of rotatable rollers  3  that are arranged in a transfer direction. A plurality of rollers  3  are separated on both sides in a width direction of the roller conveyor  2  (hereinafter, simply referred to as a width direction). The roller conveyor  2  transfers the tire T in a state in which side walls  4  are turned in an up-down direction. 
     In  FIG. 1 , the rollers  3  at positions overlapping a probe unit  6  as viewed from the front are not shown. 
     The roller conveyor  2  is provided on a stand  9 . The stand  9  is provided erect on the floor  8 . The stand  9  includes a plurality of leg portions  10 , beams  11 , and a lifting/lowering mechanism  12 . 
     A plurality of leg portions  10  extend in the up-down direction. The beams  11  are provided in upper portions and lower portions of the leg portions  10 . The beams  11  extend in a horizontal direction and are attached to stretch between adjacent leg portions  10 . 
     The lifting/lowering mechanism  12  lifts and lowers the probe unit  6 . In the embodiment, a case where the lifting/lowering mechanism  12  is attached to the upper beam is illustrated. The lifting/lowering mechanism  12  includes a base portion  13 , an upper support plate  14 , a lower support plate  15 , guide rods  16 , a guide portion  17 , a support arm  20 , and a fluid pressure cylinder  21 . 
     The base portion  13  extends in the up-down direction. The base portion  13  is fixed to the beam  11  slightly above a central portion in the up-down direction through a bracket (not shown). 
     The upper support plate  14  is provided at an upper end of the base portion  13 . The upper support plate  14  extends in the horizontal direction. 
     The lower support plate  15  is provided at a lower end of the base portion  13 . The lower support plate  15  faces the upper support plate  14 . 
     The guide rods  16  are provided between the upper support plate  14  and the lower support plate  15 . Two guide rods  16  are provided. The guide rods  16  extend in the up-down direction and are provided in parallel with each other. The guide rods  16  are disposed on both the outer sides of the base portion  13  in the width direction. 
     The guide portion  17  is liftably attached to the guide rods  16 . The guide portion  17  includes two guide tubes  18  and a frame portion  19 . The guide rods  16  are inserted into the two guide tubes  18 , respectively. The frame portion  19  connects the upper end portions of the guide tubes  18 . 
     The support arm  20  is formed in the frame portion  19  and extends upward. An upper end of the support arm  20  is fixed to a lower surface of the probe unit  6 . 
     The fluid pressure cylinder  21  is a driving source that lifts and lowers the probe unit  6 . The fluid pressure cylinder  21  includes an outer tube  22  and an inner rod  23 . The outer tube  22  extends in the up-down direction and is fixed to the lower support plate  15 . The inner rod  23  extends upward of the outer tube  22 . An upper end of the inner rod  23  is fixed to the lower surface of the probe unit  6 . 
     Such a fluid pressure cylinder  21  advances and retreats the inner rod  23  in the up-down direction due to differential pressure caused by supplying and discharging a compressed fluid into a cylinder chamber (not shown) of the outer tube  22 . That is, the inner rod  23  of the fluid pressure cylinder  21  is displaced in a contraction direction, whereby the probe unit  6  moves downward along the guide rods  16  through the guide portion  17 . With this, the probe unit  6  is moved in a downward direction being separated from the roller conveyor  2 . The inner rod  23  of the fluid pressure cylinder  21  is displaced in an expansion direction, whereby the probe unit  6  moves upward along the guide rods  16  through the guide portion  17 . With this, the probe unit  6  is moved upward, that is, a direction approaching the roller conveyor  2 . 
     The probe unit  6  measures the electric resistance of the tire T. The probe unit  6  includes a base plate  29 , a frame body  31 , a guide rod  30 , a first slide portion  32 , a second slide portion  33 , a fluid pressure cylinder  34  for a probe, outer side probes (electric resistance probes)  50 A, and an inner side probe  50 S. 
     The base plate  29  is fixed to an upper end portion of the inner rod  23 . The frame body  31  is attached to the base plate  29 . The frame body  31  supports the guide rod  30 . The guide rod  30  extends in the transfer direction in the roller conveyor  2 . The first slide portion  32  and the second slide portion  33  are slidably attached to the guide rod  30 . 
     The fluid pressure cylinder  34  for a probe is a driving source that relatively moves the first slide portion  32  and the second slide portion  33 . The fluid pressure cylinder  34  for a probe is attached to the first slide portion  32  and the second slide portion  33 . The fluid pressure cylinder  34  for a probe includes an outer tube  36  and an inner rod  35 . The inner rod  35  is provided retractably with respect to the outer tube  36 . An end portion of the inner rod  35  is fixed to the first slide portion  32 . The outer tube  36  is fixed to the second slide portion  33 . In the embodiment, an end portion of the outer tube  36  on a side where the inner rod  35  protrudes is fixed to the second slide portion  33 . 
       FIG. 2  is a partial sectional view showing a main part of the electric resistance measurement device.  FIG. 3  is a plan view showing the disposition of the outer side probes and the inner side probe of the electric resistance measurement device. 
     As shown in  FIG. 2 , two outer side probes  50 A are disposed in parallel at a predetermined interval in a circumferential direction of the tire T (hereinafter, simply referred to as a circumferential direction). In the following description, a “radial direction” means a radial direction of the tire T that is a tire to be measured. 
     As shown in  FIG. 3 , the outer side probe  50 A is disposed on the outside (on outer periphery side) of a tread part (outer peripheral portion)  70  of the tire T in the radial direction at the time of electric resistance measurement of the tire T. The inner side probe  50 S is disposed between the two outer side probes  50 A and is disposed on the inside (on the inner periphery side) in the radial direction from the outer side probes  50 A, in the circumferential direction. The inner side probe  50 S is disposed on the inside (on the inner periphery side) in the radial direction from a bead portion (inner peripheral portion)  71  of the tire T at the time of electric resistance measurement of the tire T. 
     Each outer side probe  50 A is fixed to the first slide portion  32  through a first support metal fitting  42 . The outer side probe  50 A is electrically insulated from the first support metal fitting  42  through an insulating member (not shown). The detailed configuration of the outer side probe  50 A will be described below. 
     The inner side probe  50 S is attached to the second slide portion  33  through a second support metal fitting  47 . The second support metal fitting  47  extends inclined from an upper end portion of the second slide portion  33  toward a portion slightly below a side opposite to the first slide portion  32 . The inner side probe  50 S extends upward from an upper surface of the second support metal fitting  47 . The inner side probe  50 S in the embodiment extends in a direction perpendicular to the upper surface of the second support metal fitting  47 . Similarly to the outer side probe  50 A, the inner side probe  50 S is also electrically insulated from the second support metal fitting  47  through an insulating member i. 
     The outer side probe  50 A and the inner side probe  50 S are driven to be lifted and lowered in the up-down direction by the drive of the fluid pressure cylinder  21 . The outer side probe  50 A and the inner side probe  50 S can protrude upward from between the portions of the roller conveyor  2  separated from each other in the width direction at the time of electric resistance measurement of the tire T. 
     The outer side probe  50 A and the inner side probe  50 S can move in a direction approaching each other and in a direction being separated from each other by the drive of the fluid pressure cylinder  34  for a probe. 
     The outer side probe  50 A relatively moves in the radial direction with respect to the tire T to be brought into contact with the tread part  70  formed in the outer peripheral portion of the tire T. The inner side probe  50 S relatively moves in the radial direction with respect to the tire T to be brought into contact with the bead portion  71  formed in the inner peripheral portion of the tire T. 
     In the embodiment, the fluid pressure cylinder  34  for a probe is driven in a compression direction, whereby the first slide portion  32  and the second slide portion  33  are relatively displaced in a direction approaching each other along the guide rod  30 . The outer side probe  50 A and the inner side probe  50 S are displaced in the direction approaching each other in this way, whereby it is possible to sandwich the tire T using the outer side probe  50 A and the inner side probe  50 S. On the other hand, in a case where the fluid pressure cylinder  34  for a probe is driven in an expansion direction, the first slide portion  32  and the second slide portion  33  are relatively displaced in a direction being separated from each other along the guide rod  30 . The outer side probe  50 A and the inner side probe  50 S are displaced in a direction being separated from each other, whereby the outer side probe  50 A and the inner side probe  50 S are separated from the tire T. 
     The fluid pressure cylinder  34  for a probe shown in the embodiment is supported in a floating state in which the inner rod  35  and the outer tube  36  are displaceable together along the guide rod  30 . For example, in a case where the fluid pressure cylinder  34  for a probe is driven in the compression direction, first, any one of the outer side probe  50 A and the inner side probe  50 S is brought into contact with the tire T and is stopped. Thereafter, in a case where the fluid pressure cylinder  34  for a probe is continuously driven in the compression direction, only the other one of the outer side probe  50 A and the inner side probe  50 S relatively moves in a direction approaching the tire T. 
     For example, in a case where the fluid pressure cylinder  34  for a probe is driven in the expansion direction, first, any one of the outer side probe  50 A and the inner side probe  50 S is brought into contact with the frame body  31  and is stopped. Thereafter, in a case where the fluid pressure cylinder  34  for a probe is continuously driven in the expansion direction, only the other one of the outer side probe  50 A and the inner side probe  50 S moves in a direction being separated from the tire T. 
     A support structure of the fluid pressure cylinder  34  for a probe is in the floating state in this way, whereby it is possible to appropriately sandwich the tire T using the outer side probe  50 A and the inner side probe  50 S even though a transfer position of the tire T is slightly shifted. 
       FIG. 4  is a side view showing the outer side probe of the electric resistance measurement device.  FIG. 5  is a diagram showing the outer side probe of the electric resistance measurement device and is a sectional view taken along an arrow A-A of  FIG. 4 . 
     As shown in  FIGS. 4 and 5 , the outer side probe  50 A comprises a support member  51  and a deformable portion  52 . In the following description, the radial direction of the tire T is referred to as a “radial direction Dr”, the outside in the radial direction Dr is referred to as an “outside Dro”, and the inside in the radial direction Dr is referred to as an “inside Dri”. The width direction of the tire T is referred to as a “width direction Dw”. 
     The support member  51  is fixed to the first support metal fitting  42 . Specifically, the support member  51  is fixed to the first support metal fitting  42  to extend in the width direction Dw of the tire T at the time of electric resistance measurement of the tire T. The support member  51  supports the deformable portion  52 . The support member  51  has, for example, a base portion  51   a  and a pair of side wall portions  51   b.    
     The base portion  51   a  is formed in a plate shape spreading in the circumferential direction and the width direction Dw of the tire T. A pair of side wall portions  51   b  extend from edge portions on both sides of the base portion  51   a  in the width direction Dw toward the inside Dri in the radial direction Dr of the tire T. The support member  51  includes the base portion  51   a  and a pair of side wall portions  51   b , and thus, has a U-shaped section as viewed from the width direction Dw of the tire T. The support member  51  is made of, for example, metal, resin, or a fiber-strengthened material, and has rigidity higher than the deformable portion  52  described below. 
     The deformable portion  52  includes an elastically deformable body (pressing portion)  53  and a conductive portion (driven displaceable portion)  54 . 
     As shown in  FIG. 5 , the elastically deformable body  53  is housed inside the support member  51  formed to have the U-shaped section. The elastically deformable body  53  has a base surface  53   a  that is directed toward the outside Dro in the radial direction Dr, two side surfaces  53   b  that extend from the base surface  53   a  to the inside Dri in the radial direction Dr, and a tip surface  53   c  that is directed toward the inside Dri in the radial direction Dr. 
     The base surface  53   a  is brought into contact with the base portion  51   a . The two side surfaces  53   b  are brought into contact with a pair of side wall portions  51   b , respectively. The tip surface  53   c  protrudes to the inside Dri in the radial direction Dr more than a pair of side wall portions  51   b.    
     As shown in  FIGS. 4 and 5 , the elastically deformable body  53  extends in the width direction Dw of the tire T. The elastically deformable body  53  is deformable following the radial direction Dr corresponding to an undulating shape of the tread part  70  in the width direction Dw. The elastically deformable body  53  is formed of, for example, an easily elastically deformable material, such as rubber or sponge. Undulation due to grooves formed in the tread part  70  of the tire T is not included in the undulating shape. 
     The outer side probe  50 A is relatively moved to the inside Dri in the radial direction Dr of the tire T with respect to the tire T, whereby the deformable portion  52  presses the tread part  70  of the tire T. In this case, the elastically deformable body  53  is compressed and deformed (elastically deformed) toward the outside Dro in the radial direction Dr corresponding to the undulating shape of the tread part  70  of the tire T. 
     The magnitude of the compression and deformation of the elastically deformable body  53  corresponds to the undulating shape of the tread part  70 , and compressive deformation is greater in a protrusion than in a dent of the undulating shape. The compressed and deformed elastically deformable body  53  energizes the conductive portion  54  toward the inside Dri in the radial direction Dr of the tire T with elasticity. 
     The conductive portion  54  is attached to the tip surface  53   c  of the elastically deformable body  53 . In other words, the conductive portion  54  is provided in a contact surface of the deformable portion  52  that is brought into contact with the tread part  70  of the tire T. The conductive portion  54  (band-shaped member  54   t ) has electric conductivity. The conductive portion  54  extends in the width direction Dw of the tire T. The conductive portion  54  has flexibility capable of following the deformation of the tip surface  53   c  of the elastically deformable body  53  corresponding to the undulating shape of the tread part  70 . The conductive portion  54  shown in the embodiment is the band-shaped member  54   t  made of a commercially available conductive tape or the like. As the band-shaped member  54   t , for example, a material having electric conductivity (in other words, having extremely low electric resistance), such as copper, silver, or aluminum. 
     As shown in  FIG. 4 , both end portions of the conductive portion  54  are fixed to the support member  51  by screws  52   k  or the like. In a case where the conductive portion  54  is brought into contact with the tread part  70  of the tire T by relatively moving in the radial direction Dr of the tire T with respect to the tire T, the conductive portion  54  is sandwiched between the tread part  70  and the tip surface  53   c  and is deformed following the deformation of the tip surface  53   c  of the elastically deformable body  53 . That is, the conductive portion  54  is deformed along the undulating shape of the tread part  70  of the tire T. 
       FIG. 6  is a sectional view showing a state in which the outer side probe of the electric resistance measurement device is pressed to the tread part of the tire. 
     As shown in  FIG. 6 , in a state in which the tire T that is filled with a fluid, such as air or nitrogen gas, for use is not filled with the fluid, there is a case where a part of the tread part  70  (outer peripheral portion) in the width direction Dw of the tire T is dented to the inside Dri in the radial direction Dr. In the embodiment, for example, a case where a dent  73  (dent) more dented to the inside Dri in the radial direction Dr than a maximum outer diameter portion  75  of the tire T in an intermediate portion in the width direction Dw of the tire T in the tread part  70  of the tire T. 
     With the above-described outer side probe  50 A, the deformable portion  52  relatively moves in the radial direction Dr of the tire T with respect to the tire T and is pressed to the tread part  70  of the tire T. In this case, the outer side probe  50 A is brought into contact in a range from a center portion C to a shoulder portion S of the tread part  70  in the width direction Dw of the tire T (in other words, the axial direction of the tire T). 
     More specifically, the elastically deformable body  53  and the conductive portion  54  of the deformable portion  52  are pressed to the tread part  70  to be deformed along the undulating shape of the tread part  70  of the tire T in the width direction Dw. In this case, the elastically deformable body  53  is compressed and deformed toward the outside Dro in the radial direction Dr corresponding to the undulating shape of the tread part  70  of the tire T. The compressed and deformed elastically deformable body  53  exerts pressing force P toward the inside Dri in the radial direction Dr and energizes the conductive portion  54  with elasticity. With this, the conductive portion  54  enters a dent  73  formed in the intermediate portion in the width direction Dw of the tire T while being brought into close contact with the maximum outer diameter portion  75  of the tire T and is brought into close contact with a tread part of the dent  73 . The above-described shoulder portion S means a portion near the end portion in the width direction Dw in the tread part  70  coming into contact with the ground when a vehicle travels. 
     As shown in  FIG. 3 , the inner side probe  50 S has sufficient rigidity that is not deformed when being pressed by the bead portion  71  and has electric conductivity. The inner side probe  50 S in the embodiment is formed of a rod-shaped member. The inner side probe  50 S is slightly inclined such that an end portion is disposed further toward an axial center side of the tire T than a base portion. With this, in a case where the width dimension of the tire T is shorter than the length dimension of the inner side probe  50 S, or the like, the inner side probe  50 S is not brought into contact with the bead portion  71  on a side in the width direction Dw opposite to the bead portion  71  to be measured. 
     A resistance measurement instrument (measurement unit)  60  is connected to the outer side probe  50 A and the inner side probe  50 S through wires W 1  and W 2 . 
     The resistance measurement instrument  60  applies a predetermined measurement current, for example, between the outer side probe  50 A and the inner side probe  50 S, and measures a voltage across terminals in this case to measure electric resistance between the outer side probe  50 A and the inner side probe  50 S. 
     According to the above-described first embodiment, the outer side probe  50 A extends in the width direction Dw of the tire T and is deformable following the radial direction Dr corresponding to the undulating shape of the tread part  70  in the width direction Dw. The conductive portion  54  is provided in at least the contact surface of the deformable portion  52  with the tread part  70  of the tire T and has electric conductivity. According to such a configuration, even though a part of the tire T in the width direction Dw is dented to the inside Dri in the radial direction Dr of the tire T, the deformable portion  52  and the conductive portion  54  can enter the dent  73  dented to the inside Dri in the radial direction Dr. For this reason, even in a case where a low electric resistance portion  100  of the tire T is positioned in the dent  73  dented to the inside Dri in the radial direction Dr of the tire T, it is possible to bring the conductive portion  54  into contact with the low electric resistance portion  100  to correctly measure the electric resistance of the tire T. 
     In the above-described first embodiment, in a case where the outer side probe  50 A is brought into contact with the tread part  70  of the tire T, the deformable portion  52  enters the dent  73  dented to the inside Dri in the radial direction Dr of the tire T. For this reason, even in a case where the low electric resistance portion  100  is positioned in the dent  73  dented to the inside Dri in the radial direction Dr of the tire T, it is possible to bring the conductive portion  54  into contact with the low electric resistance portion  100 . 
     In the above-described first embodiment, the electric resistance measurement device  1  and the outer side probe  50 A further include the support member  51  having rigidity higher than the deformable portion  52 . With this, when the deformable portion  52  is brought into contact with the tread part  70  of the tire T and is deformed in the radial direction Dr corresponding to the undulating shape of the tread part  70  in the width direction Dw, the support member  51  firmly supports the deformable portion  52  on the outside Dro in the radial direction Dr. With this, it is possible to make the deformable portion  52  stably enter the dent  73  more dented to the inside Dri in the radial direction Dr than the maximum outer diameter portion  75  of the tire T. 
     In the above-described first embodiment, the deformable portion  52  includes the conductive portion  54  and the elastically deformable body  53 . In a case where the conductive portion  54  is brought into contact with the tread part  70  of the tire T, the conductive portion  54  is displaced to be pressed to the outside Dro in the radial direction Dr corresponding to the undulating shape of the tread part  70  of the tire T. The conductive portion  54  is pressed to the inside Dri in the radial direction Dr of the tire T by the elastically deformable body  53 , and thus, enters the dent  73 . For this reason, even in a case where the low electric resistance portion  100  is positioned in the dent  73  dented to the inside Dri in the radial direction Dr of the tire T, it is possible to bring the conductive portion  54  into contact with the low electric resistance portion  100 . 
     In the above-described first embodiment, the conductive portion  54  is made of the band-shaped member  54   t  that extends in the width direction Dw and has flexibility and electric conductivity. With this, conductive portion  54  enters the dent  73  more dented to the inside Dri in the radial direction Dr than the maximum outer diameter portion  75  of the tire T. The band-shaped member  54   t  has electric conductivity, and thus, functions as the conductive portion  54 . For this reason, even in a case where the low electric resistance portion  100  is positioned in a portion dented to the inside Dri in the radial direction Dr of the tire T, it is possible to bring the conductive portion  54  into contact with the low electric resistance portion  100 . 
     In the above-described first embodiment, the elastically deformable body  53  is elastically deformed and compressed toward the outside Dro in the radial direction Dr, and exerts the pressing force P toward the inside Dri in the radial direction Dr with elasticity. With this, the conductive portion  54  is energized toward the inside Dri in the radial direction Dr of the tire T by the pressing force P. For this reason, it is possible to make the conductive portion  54  enter the dent  73  more dented to the inside Dri in the radial direction Dr than the maximum outer diameter portion  75  of the tire T. 
     (Modification Example of First Embodiment)  FIG. 7  is a sectional view showing a state in which an outer side probe of an electric resistance measurement device in a modification example of the embodiment is pressed to a tread part of a tire. 
     In the first embodiment, although the band-shaped member  54   t  is used as the conductive portion  54 , the invention is not limited thereto. 
     As in the modification example of the first embodiment shown in  FIG. 7 , a coil spring  54   c  made of a material, such as metal, having electric conductivity may be used as a conductive portion  54 B of an outer side probe (electric resistance probe)  50 B. Similarly to the above-described band-shaped member  54   t , the coil spring  54   c  is attached to the tip surface  53   c  of the elastically deformable body  53 . In other words, the coil spring  54   c  is provided in the contact surface of the deformable portion  52 B with the tread part  70 . 
     With the above-described outer side probe  50 B, similarly to the deformable portion  52  of the first embodiment, the deformable portion  52 B relatively moves in the radial direction Dr of the tire T with respect to the tire T and is brought into contact in a range from the center portion C to the shoulder portion S the tread part  70  in the width direction Dw of the tire T. 
     More specifically, the coil spring  54   c  (conductive portion  54 B) and the elastically deformable body  53  of the deformable portion  52 B are pressed to the tread part  70  to be deformed along the undulating shape of the tread part  70  of the tire T in the width direction Dw. In this case, the elastically deformable body  53  is compressed and deformed toward the outside Dro in the radial direction Dr corresponding to the undulating shape of the tread part  70  of the tire T. The compressed and deformed elastically deformable body  53  energizes the coil spring  54   c  toward the inside Dri in the radial direction Dr by the pressing force P with elasticity. With this, the coil spring  54   c  enters the dent  73  formed in the intermediate portion in the width direction Dw of the tire T while being brought into contact with the maximum outer diameter portion  75  of the tire T and is brought into contact with the tread surface of the dent  73 . Here, a portion in the coil spring  54   c  disposed on the inside Dri in the radial direction Dr is brought into contact with the tread part  70  of the tire T over the entire region in the width direction Dw of the tire T. 
     Second Embodiment 
     Next, a second embodiment of the invention will be described referring to the drawings. The second embodiment is different from the first embodiment only in that an electric resistance probe is different. Accordingly, in the description of the second embodiment, the same portions as those in the first embodiment are represented by the same reference numerals while referring to  FIG. 1  and overlapping description will not be repeated. That is, description of the overall configuration of the electric resistance measurement device  1  common to the configuration described in the first embodiment will not be repeated. 
       FIG. 8  is a sectional view showing a state in which an outer side probe of an electric resistance measurement device in the second embodiment is pressed to a tread part of a tire. 
     As shown in  FIG. 1 , the probe unit  6  of the electric resistance measurement device  1  in the second embodiment has an outer side probe (electric resistance probe)  50 C and an inner side probe  50 S. 
     As shown in  FIG. 8 , the outer side probe  50 C includes a support member  51  and a deformable portion  52 C. 
     The deformable portion  52 C includes an elastically deformable body (pressing portion)  55  and a driven displaceable portion  56 . 
     The driven displaceable portion  56  is provided at a position in the deformable portion  52 C on the inside Dri in the radial direction Dr of the tire T. In other words, the driven displaceable portion  56  is provided at a position in the deformable portion  52 C capable of being brought into contact with the tread part  70 . The driven displaceable portion  56  includes a plurality of conductive pins (advance/retreat members)  56   p  and a holding member  56   h.    
     A plurality of conductive pins (advance/retreat members)  56   p  are disposed at intervals in the width direction Dw of the tire T. A plurality of conductive pins  56   p  extend in the radial direction Dr of the tire T. Each conductive pin  56   p  can be formed of, for example, a material having electric conductivity, such as copper, silver, or aluminum. 
     The holding member  56   h  holds a plurality of conductive pins  56   p  in a state of being advanceable and retreatable in the radial direction Dr of the tire T. The holding member  56   h  shown in the second embodiment supports a plurality of conductive pins  56   p  to be slidable in the radial direction Dr. The holding member  56   h  has electric conductivity and is electrically connected to a plurality of conductive pins  56   p . A plurality of conductive pins  56   p  described above are electrically connected to the resistance measurement instrument  60  (see  FIG. 3 ) through the holding member  56   h.    
     The holding member  56   h  is fixed to the support member  51 . The holding member  56   h  extends in the width direction Dw in front view shown in  FIG. 8 . Similarly to the support member  51 , the holding member  56   h  also has rigidity higher than the elastically deformable body  55 . The rigidity of the holding member  56   h  may be equal to the rigidity of the support member  51 . 
     The outer side probe  50 C relatively moves in the radial direction Dr of the tire T with respect to the tire T, whereby each conductive pin  56   p  is brought into contact with the tread part  70  of the tire T. A plurality of conductive pins  56   p  are displaced to the outside Dro in the radial direction Dr corresponding to the undulating shape of the tread part  70  of the tire T. Specifically, the tip of each of a plurality of conductive pins  56   p  is pressed by the tread part  70  to be driven and is displaced corresponding to the undulating shape of the tread part  70  of the tire T. 
     Similarly to the elastically deformable body  53  in the first embodiment, the elastically deformable body  55  is supported by the support member  51 . The elastically deformable body  55  can be formed of, for example, rubber or sponge. 
     A base end of each of a plurality of conductive pins  56   p  elastically deformable body  55 . The elastically deformable body  55  is compressed and deformed (elastically deformed) toward the outside Dro in the radial direction Dr in a case where a plurality of conductive pins  56   p  are displaced in the radial direction Dr corresponding to the undulating shape of the tread part  70  of the tire T. The compressed and deformed elastically deformable body  55  presses a plurality of conductive pins  56   p  to the inside Dri in the radial direction Dr of the tire T by the pressing force P with elasticity. 
     With the above-described outer side probe  50 C, the outer side probe  50 C relatively moves the radial direction Dr of the tire T with respect to the tire T, whereby a plurality of conductive pins  56   p  of the driven displaceable portion  56  are brought into contact with the tread part  70  of the tire T. A plurality of conductive pins  56   p  are displaced to the outside Dro in the radial direction Dr along the undulating shape of the tread part  70  of the tire T in the width direction Dw, whereby the elastically deformable body  55  is deformed. Then, the elastically deformable body  55  exerts the pressing force P toward the inside Dri in the radial direction Dr and presses a plurality of conductive pins  56   p  toward the inside Dri in the radial direction Dr. With this, the driven displaceable portion  56  enters the dent  73  formed in the intermediate portion in the width direction Dw of the tire T while being brought into contact with the maximum outer diameter portion  75  of the tire T and is brought into contact with the tread surface of the dent  73 . In this case, a portion (the tip of each of a plurality of conductive pins  56   p ) in the driven displaceable portion  56  disposed on the inside Dri in the radial direction Dr is brought into contact with the tread part  70  of the tire T over the entire region in the width direction Dw of the tire T. 
     According to the above-described second embodiment, the deformable portion  52 C extends in the width direction Dw of the tire T and is deformable following the radial direction Dr corresponding to the undulating shape of the tread part  70  in the width direction Dw. The driven displaceable portion  56  is provided in at least the contact surface of the deformable portion  52 C with the tread part  70  and has electric conductivity. With such a configuration, even in a case where the low electric resistance portion  100  is positioned in a portion dented to the inside Dri in the radial direction Dr of the tire T, it is possible to bring the driven displaceable portion  56  into contact with the low electric resistance portion  100  to correctly measure the electric resistance of the tire T. 
     In the above-described second embodiment, the driven displaceable portion  56  includes a plurality of conductive pins  56   p  that are provided at intervals in the width direction Dw and are provided advanceable and retreatable in the radial direction Dr. With such a configuration, the outer side probe  50 C relatively moves in the radial direction Dr with respect to the tire T to be brought into contact with the tread part  70  of the tire T. With the contact with the tread part  70 , each of the conductive pins  56   p  configuring the driven displaceable portion  56  is displaced to be pressed to the outside Dro in the radial direction Dr corresponding to the undulating shape of the tread part  70  of the tire T. A plurality of conductive pins  56   p  are pressed to the inside Dri in the radial direction Dr of the tire T by the elastically deformable body  55 , and thus, enter the dent  73 . For this reason, even in a case where the low electric resistance portion  100  is positioned in a portion dented to the inside Dri in the radial direction Dr of the tire T, it is possible to bring the conductive portion  54  into contact with the low electric resistance portion  100 . 
     (Modification Example of Second Embodiment) In the second embodiment, although rubber, sponge, or the like is used as the elastically deformable body  55 , the invention is not limited thereto. As the elastically deformable body  55 , a spring member (not shown) that presses a plurality of conductive pins  56   p  individually to the inside Dri in the radial direction Dr of the tire T, such as a coil spring or a spring plate, may be used. The elastically deformable body  55  using such a spring member is compressed and deformed (elastically deformed) toward the outside Dro in the radial direction Dr corresponding to the undulating shape of the tread part  70  of the tire T. The compressed and deformed elastically deformable body  55  energizes a plurality of conductive pins  56   p  toward the inside Dri in the radial direction Dr with elasticity. 
     Instead of the elastically deformable body  55  of the second embodiment, an actuator (not shown) that presses a plurality of conductive pins  56   p  toward the inside Dri in the radial direction Dr of the tire T can be employed. In this case, a plurality of conductive pins  56   p  that are displaced to the outside Dro in the radial direction Dr corresponding to the undulating shape of the tread part  70  of the tire T may be pressed toward the inside Dri in the radial direction Dr by the actuator. 
     Third Embodiment 
     Next, a third embodiment of the invention will be described referring to the drawings. The third embodiment is different from the second embodiment only in that an electric resistance probe is different. For this reason, in the description of the third embodiment, the same portions as those in the second embodiment are represented by the same reference numerals while referring to  FIG. 1  and overlapping description will not be repeated. That is, description will be provided focusing on a difference from the second embodiment, and description of the configuration common to the configuration described in the first embodiment and the second embodiment will not be repeated. 
       FIG. 9  is a sectional view showing a state in which an outer side probe of an electric resistance measurement device in the third embodiment is pressed to a tread part of a tire. 
     As shown in  FIG. 1 , the probe unit  6  of the electric resistance measurement device  1  of the tire T has an outer side probe (electric resistance probe)  50 E and an inner side probe  50 S. 
     As shown in  FIG. 9 , the outer side probe  50 E includes a support member  51  and a deformable portion  52 E. 
     Similarly to the elastically deformable body  53  in the above-described first embodiment, the deformable portion  52 E is supported by the support member  51 . The deformable portion  52 E extends in the width direction Dw of the tire T and is deformable in the radial direction Dr corresponding to the undulating shape of the tread part  70  in the width direction Dw. The deformable portion  52 E is formed of, for example, rubber or sponge. The deformable portion  52 E is compressed and deformed toward the outside Dro in the radial direction Dr corresponding to the undulating shape of the tread part  70  of the tire T in a case of relatively moving in the radial direction Dr of the tire T with respect to the tire T to be brought into contact with the tread part  70  of the tire T. The compressed and deformed deformable portion  52 E exerts the pressing force P toward the inside Dri in the radial direction Dr with elasticity. The deformable portion  52 E has electric conductivity by kneading particles made of metal, carbon black, or the like having electric conductivity. That is, the deformable portion  52 E is also used as a conductive portion  54 E as a whole. The conductive portion  54 E is electrically connected to the resistance measurement instrument  60  (see  FIG. 3 ). 
     According to the above-described third embodiment, the deformable portion  52 E of the outer side probe  50 E extends in the width direction Dw of the tire T and is deformable in the radial direction Dr corresponding to the undulating shape of the tread part  70  in the width direction Dw. With this, the deformable portion  52 E can enter the dent  73  dented to the inside Dri in the radial direction Dr. For this reason, even in a case where the low electric resistance portion  100  is positioned in a portion dented to the inside Dri in the radial direction Dr of the tire T, it is possible to bring the deformable portion  52 E (conductive portion  54 E) into contact with the low electric resistance portion  100  to correctly measure the electric resistance of the tire T. Furthermore, since the portion of the deformable portion  52 E that is elastically deformed is also used as the conductive portion  54 E, it is possible to efficiently perform manufacturing or the like of the outer side probe  50 E. 
     Other Embodiments 
     The invention is not limited to the above-described embodiments, and design changes can be made without departing from the spirit and scope of the invention. 
     For example, in each embodiment and each modification example described above, the upper end portion of the outer side probe  50 A,  50 B,  50 C, or  50 E is disposed at a slightly higher position in the height direction than the center portion C of the tire T. However, the height of the upper end portion of the outer side probe  50 A,  50 B,  50 C, or  50 E is not limited to the above height. For example, the upper end portion of the outer side probe  50 A,  50 B,  50 C, or  50 E may be disposed at a height position equal to or higher than the center portion C at the highest position among the center portions C of a plurality of types of tires T assumed as a target to be inspected. 
     In each embodiment and each modification example described above, an example where the two outer side probes  50 A,  50 B,  50 C, or  50 E are disposed in parallel in the circumferential direction has been described. However, only one outer side probe  50 A,  50 B,  50 C, or  50 E may be disposed. In each embodiment and each modification example described above, a case where only one inner side probe  50 S is disposed has been described. However, a plurality of inner side probes  50 S may be provided in the circumferential direction. 
     In each embodiment and each modification example described above, although a case where the inner side probe  50 S is disposed inclined has been described, the inner side probe  50 S may be disposed to extend vertically upward or an inclination angle may be changeable as needed. 
     In the above-described embodiments, although a case where the probe unit  6  is displaced in the up-down direction by the lifting/lowering mechanism  12  has been described, the direction of displacing the probe unit  6  is not limited to the up-down direction, and may be a direction corresponding to the posture of the tire T at the time of transfer. 
       FIG. 10  is a diagram showing an inner side probe in a modification example of the embodiment of the invention. 
     In the above-described embodiments, a case where only the outer side probe  50 A,  50 B,  50 C, or  50 E among the inner side probe  50 S and the outer side probe  50 A,  50 B,  50 C, or  50 E is deformable following the radial direction Dr corresponding to the undulating shape of the tire T has been described. 
     However, like the inner side probe  50 S in the modification example shown in  FIG. 10 , the inner side probe  50 S may have the same configuration as the above-described outer side probe  50 A,  50 B,  50 C, or  50 E, that is, may be configured to be deformable following the radial direction Dr corresponding to the undulating shape of the tire T. 
     As shown in  FIG. 10 , the inner side probe  50 S in the modification example relatively moves to the outside Dro in the radial direction Dr with respect to the tire T to be brought into contact with the bead portion  71  formed in the inner peripheral portion of the tire T. The inner side probe  50 S includes a support member  51 S and a deformable portion  52 S. The deformable portion  52 S includes an elastically deformable body  53 S and a conductive portion  54 S. The support member  51 S is configured similarly to any one of the support members  51  in the above-described embodiments. The deformable portion  52 S is configured similarly to any one of the deformable portions  52 ,  52 B,  52 C, and  52 E in the above-described embodiments. 
     The inner side probe  50 S in the modification example of the embodiment in this way is deformable following the radial direction Dr corresponding to the undulating shape of the bead portion  71  and has electric conductivity in at least the contact surface with the bead portion  71 . For this reason, it is possible to stably bring the conductive portion  54 S of the inner side probe  50 S into contact with an electric conduction portion  100 S exposed in the bead portion  71 . 
     INDUSTRIAL APPLICABILITY 
     With the tire electric resistance measurement device and the electric resistance probe described above, it is possible to improve reliability in electric resistance measurement of a tire. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1 : electric resistance measurement device 
               2 : roller conveyor 
               3 : roller 
               4 : side wall 
               6 : probe unit 
               8 : floor 
               9 : stand 
               10 : leg portion 
               11 : beam 
               12 : lifting/lowering mechanism 
               13 : base portion 
               14 : upper support plate 
               15 : lower support plate 
               16 : guide rod 
               17 : guide portion 
               18 : guide tube 
               19 : frame portion 
               20 : support arm 
               21 : fluid pressure cylinder 
               22 : outer tube 
               23 : inner rod 
               29 : base plate 
               30 : guide rod 
               31 : frame body 
               32 : first slide portion 
               33 : second slide portion 
               34 : fluid pressure cylinder for probe 
               35 : inner rod 
               36 : outer tube 
               42 : first support metal fitting 
               47 : second support metal fitting 
               50 A,  50 B,  50 C,  50 E: outer side probe (electric resistance probe) 
               50 S: inner side probe 
               51 : support member 
               51   a : base portion 
               51   b : side wall portion 
               52 ,  52 B,  52 C,  52 E: deformable portion 
               52   k : screw 
               53 ,  55 : elastically deformable body (pressing portion) 
               53   a : base surface 
               53   b : side surface 
               53   c : tip surface 
               54 ,  54 B: conductive portion (driven displaceable portion) 
               54 E: conductive portion 
               54   c : coil spring 
               54   t : band-shaped member 
               56 : driven displaceable portion 
               56   h : holding member 
               56   p : conductive pin (advance/retreat member) 
               60 : resistance measurement instrument 
               70 : tread part 
               71 : bead portion 
               73 : dent 
               75 : maximum outer diameter portion 
               100 : low electric resistance portion 
             C: center portion 
             Dr: radial direction 
             Dri: inside 
             Dro: outside 
             Dw: width direction 
             P: pressing force 
             S: shoulder portion 
             T: tire 
             W 1 : wire 
             W 2 : wire 
             i: insulating member