Pneumatic tire bead and sidewall construction

A pneumatic tire comprises a tread; a bead region, a sidewall; a bead core; a first apex; an apex-extension; a carcass; a chafer and a second apex. The second apex is positioned between a rim flange protector and the first apex or the extension. The carcass includes a first ply turned-up around the bead core to form a first turnup portion extending along the first apex and the extension and terminating radially inwardly from the radially outward end of the extension. The carcass may include a second ply turned-up, between the bead core and the first ply, around the bead core to form a second turnup portion, the second turnup portion extending along the axially outer side of the first apex. Alternatively, the carcass may include a second ply parting from the first ply at the extension and extending along the extension and the turnup portion of the first ply.

FIELD OF THE INVENTION

The present invention relates to a pneumatic tire and, more specifically, to a pneumatic bead and sidewall construction.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 11,254,167 B2 discloses a pneumatic tire that includes a tread portion, two axially spaced sidewall portions extending radially inwardly from the tread portion, at least one of the sidewall portions being provided with a side protector that protrudes axially outwardly and having an inner end located radially outwardly of a tire-maximum-width position, and two axially spaced bead portions connected to radially inward of the respective sidewall portions. Each bead portion includes a bead apex rubber having an outer end in the tire radial direction being located radially inwardly of the tire-maximum-width position. A radial length of a tire inner region from a bead baseline to the outer end of each bead apex rubber is in a range of from 0.8 to 1.2 times a radial length of a tire outer region from a radially outermost position of the tread portion to the inner end of the side protector.

US 2020/114701 A1 relates to a tire including a tread, a sidewall extending from one edge of the tread approximately in a radially inward direction to a bead structure, and a carcass extending along an axially inner side of the sidewall to the bead structure. The carcass includes a first ply and a second ply extending radially inward from the sidewall to a terminal end directly adjacent the bead structure. The bead structure includes a circumferentially extending bead core axially inward of the sidewall, a chafer extending radially inward toward the bead core, an apex abutting the bead core, and an inner stiffener member disposed between the first ply and the apex, the inner stiffener member extending radially outward from a location proximate the bead core to a location radially outward from the apex.

US 2023/256779 A1 discloses a tire, wherein an apex of each bead includes an apex body, a strip apex, and an intermediate apex. The inner end of the strip apex is located between a ply body of a carcass ply and the apex body. The inner end of the intermediate apex is located between the strip apex and the apex body. The outer end of the apex body is located between the inner and outer ends of the intermediate apex. The intermediate apex is located between the inner and outer ends of the strip apex. The intermediate apex is harder than the apex body, and the strip apex is harder than the intermediate apex.

JP 2023050713 A relates to a tire that includes a pair of beads, a carcass, and a pair of strip apexes. The inner end of each of the strip apexes is located between a ply body and an apex. The outer end of each of the strip apexes is located in the radially outside of an end of a folding part of a first ply. The inner end of each of the strip apexes is located in the radially outside of an end of a folding part of a second ply.

JP 2015174515 A discloses a pneumatic tire, comprising: a tread; a pair of side walls; a pair of beads; a carcass; and a pair of strip apexes. The beads respectively comprise a core and an apex. The strip apexes are laminated in a radial direction outside of the apex. The strip apexes respectively comprise: a tip end lamination part laminated on a tip end of the apex and extending outward in the radial direction from the tip end; and an inside lamination part laminated on the apex in the radial direction inside of the tip end lamination part. The rigidity of the tip end lamination part is larger than that of the inside lamination part.

U.S. Pat. No. 6,318,431 B1 relates to a heavy-duty radial tire. The tire has a carcass including a carcass ply made of cords arranged at an inclination angle of 70 to 90 degrees with respect to the tire equator, the carcass ply including a main portion extending from a tread portion to a bead core in a bead portion and integrally provided with a turnup portion turned up from the axially inside to the outside at the bead core, a bead apex disposed between the main portion and turnup portion of the carcass ply, wherein the turnup portion extends radially outwardly along the axially outer surface of the bead apex and has a portion extending substantially parallel with and adjacent to the carcass ply main portion from the radially outer end of the bead apex, and the length L of the parallel portion is 1.0 to 8.0 times the maximum section width of the bead core.

U.S. Pat. No. 5,479,977 A discloses a pneumatic tire having a carcass structure increasing the sidewall rigidity. The tire comprises a carcass composed of an inner carcass ply and an outer carcass ply, the inner carcass ply having a pair of edges turned up around the bead cores from the axially inside to outside of the tire, each turned up portion thereof extending radially outwardly beyond the maximum tire width point, a bead apex disposed between the main portion and the turned up portion, the outer carcass ply having a pair of edges each disposed between the bead apex and each turned up portion of the inner carcass ply, the edges of the outer carcass ply terminated radially outward of the radially inner end of the bead core, each sidewall portion provided with at least one steel cord reinforcing layer made of parallel steel cords.

Chinese utility model CN 210652552 U relates to a semi-steel radial tire with an apex-extending rubber sheet. The tire includes a sidewall. A rim is set against the bottom of the sidewall. A first carcass ply is bent away from the inner wall of the sidewall at a position close to the rim to form a first turned-up portion. A second carcass ply is bent away from the inner wall of the sidewall at a position closer to the bead core. The turned-up portion is bonded to the apex, which gradually decreases in cross-section from the side close to the rim toward the top of the sidewall. An apex-extending rubber sheet is provided on the top end of the apex facing away from the rim.

SUMMARY OF THE INVENTION

In a first aspect, the invention relates to a pneumatic tire, e.g., a radial light-truck(LT) tire, comprising:a tread;a bead region,a sidewall extending from an edge of the tread generally in a radially inward direction to the bead region;a circumferentially extending bead core arranged in the bead region;a first apex extending from the bead core in radially outward direction;an apex extension extending in radially outward direction from the first apex, the apex extension having a radially inward end and a radially outward end;a carcass extending along an axially inner side of the sidewall to the bead region, the carcass including:a first ply turned up around the bead core from an axially inner side to an axially outer side of the bead core so as to form a first turnup portion, the first turnup portion extending along an axially outer side of the first apex and along an axially outer side of the apex extension and terminating radially inwardly from the radially outward end of the apex extension, anda second ply turned up, between the bead core and the first ply, around the bead core from an axially inner side to an axially outer side of the bead core so as to form a second turnup portion, the second turnup portion extending along the axially outer side of the first apex;a chafer positioned around at least a portion of the bead core and the first and second turnup portions, the chafer intended for contacting a rim of a wheel, the chafer comprising a toe guard and a rim flange protector; anda second apex positioned between the rim flange protector and at least one of the first apex and the apex extension.

The bead core may comprise, e.g., a hexagonal bead bundle or a square bead bundle. The bead core could have a diameter of 6 to 12 mm, but other diameter values may also be selected.

The first apex may taper in radially outward direction. The apex extension may be arranged in abutment on a radially outward extremity of the first apex. The apex extension may extend in a continuation of the first apex in radially outward direction. The apex extension may also be arranged overlapping with a radially outward extremity of the first apex. The radial extent of the overlap region preferably amounts to at most 30% of the radial extent of the first apex.

The apex extension may be of substantially uniform thickness over its radial extent.

According to an embodiment, the second turnup portion may extend along the axially outer side of the apex extension and terminate radially inwardly from the radially outward end of the apex extension.

According to an embodiment, the second turnup portion may terminate radially inwardly from the termination of the first turnup portion.

The second apex may comprise a radially inward region tapering in radially inward direction, a radially outward region tapering in radially outward direction and a bulged transition region between the radially outward region and the radially inward region. The second apex may have a preferred thickness from 3 to 7 mm in the bulged transition region.

The bead region may include a bead base, a rim flange contacting area, and a bead heel between the bead base and the flange contacting area. A reference point for indication of radial positions in the bead region (and in the sidewall region) may be defined as being located on the bead heel, in a position that is closest to an intersection of a straight-line continuation of the bead base and a straight-line continuation of the flange contacting area. According to an embodiment, the radially outward termination of the first turnup portion may be located at a distance from 40 to 110 mm from the reference point. The radially outward termination of the second turnup portion may be located at a distance from 25 to 80 mm from the reference point. The radially outward end of the apex extension may be located at a distance from 35 to 120 mm from the reference point.

The second apex may have a radially inward end located at a distance from 5 to 25 mm from the reference point and a radially outward end located at a distance from 35 to 70 mm from the reference point.

In a second aspect, the invention relates to a pneumatic tire, e.g., a radial LT tire, comprising:a tread;a bead region,a sidewall extending from an edge of the tread generally in a radially inward direction to the bead region;a circumferentially extending bead core arranged in the bead region;a first apex extending from the bead core in radially outward direction;an apex extension extending in radially outward direction from the first apex, the apex extension having a radially inward end and a radially outward end;a carcass extending along an axially inner side of the sidewall to the bead region, the carcass including:a first ply turned up around the bead core from an axially inner side to an axially outer side of the bead core so as to form a turnup portion, the turnup portion extending along an axially outer side of the first apex and along an axially outer side of the apex extension and terminating radially inwardly from the radially outward end of the apex extension; anda second ply arranged alongside the first ply but parting from the first ply at the radially outward end of the apex extension and extending into the bead region along the axially outer side of the apex extension and along an axially outer side of the turnup portion of the first ply;a chafer positioned around at least a portion of the bead core and the turnup portion of the first ply, the chafer intended for contacting a rim of a wheel, the chafer comprising a toe guard and a rim flange protector; anda second apex positioned between the rim flange protector and at least one of the first apex and the apex extension.

The bead core may comprise, e.g., a hexagonal bead bundle or a square bead bundle. The bead core could have a diameter of 6 to 12 mm, but other diameter values may also be selected.

The first apex may have a taper in radially outward direction. The apex extension may be arranged in abutment on a radially outward extremity of the first apex. The apex extension may extend in a continuation of the first apex in radially outward direction. The apex extension may also be arranged overlapping with a radially outward extremity of the first apex. The radial extent of the overlap region preferably amounts to at most 30% of the radial extent of the first apex.

The apex extension may be of substantially uniform thickness over its radial extent.

According to an embodiment, the second ply may terminate radially inwardly from a radially outward end of the second apex.

The second apex may comprise a radially inward region tapering in radially inward direction, a radially outward region tapering in radially outward direction and a bulged transition region between the radially outward region and the radially inward region. The second apex may have a preferred thickness from 3 to 7 mm in the bulged transition region.

The bead region may include a bead base, a flange contacting area, and a bead heel between the bead base and the flange contacting area.

A reference point for indication of radial positions in the bead region (and in the sidewall region) may be defined as being located on the bead heel, in a position that is closest to an intersection of a straight-line continuation of the bead base and a straight-line continuation of the flange contacting area. According to embodiments, the radially outward termination of the first turnup portion may be located at a distance from 30 to 110 mm from the reference point. The radially inward termination of the second ply may be located at a distance from 0 to 15 mm from the reference point. The radially outward end of the apex extension may be located at a distance from 35 to 120 mm from the reference point.

The second apex may have a radially inward end located at a distance from 5 to 25 mm from the reference point and a radially outward end located at a distance from 35 to 70 mm from the reference point.

DEFINITIONS

The following definitions are applicable to the present disclosure:

“Apex” means a rubber filler in the bead and lower sidewall area to provide progressive transition from the stiff bead area into the flexible sidewall. The “first apex” herein means an apex located radially outwardly of the bead core and between at least one carcass ply and at least one turnup portion.

“Axial” and “axially” are used herein to refer to lines or directions that are parallel to the axis of rotation of the tire.

“Bead base” means a portion of the bead region that forms its inside (radially inner) diameter.

“Bead core” means an annular tensile member in the bead region of the tire, which may, e.g., be formed of a bundle of steel wire, cords, or cables (“bead bundle”). The bead core seats the tire on the rim and maintains it in position.

“Bead heel” means the curved area of the bead region that is tangent the bead base and the rim flange contacting area of the bead region.

“Bead Region” means the part of the tire that comprises an annular tensile member wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes, toe guards and chafers, to fit the design rim.

“Bead toe” or “toe guard” means the portion of the bead region the joins the bead base and the axially inside surface of the tire.

“Belt package” (also: “breaker package”) means a structure of at least two rubber-coated steel cord layers, woven or unwoven, between the tread and the carcass. The belt package provides strength to the tire, stabilizes the tread, and prevents cuts or perforations in the tread from reaching the carcass ply or plies.

“Carcass ply” or simply “ply” designates a continuous layer of rubber-coated reinforcing cords extending from one bead region to the other by describing an open toroidal form. A carcass ply may comprise turnup portions wrapped around the bead cores.

“Chafer” means an element of rubber, e.g., hard rubber, with or without fabric reinforcement, that resists erosion (chafing) of the bead region by the rim.

“Circumferential” means lines or directions extending along the perimeter of the surface of the annular tire parallel to the Equatorial Plane (EP) and perpendicular to the axial direction.

“Equatorial plane” means the plane perpendicular to the tire's axis of rotation and passing through the center of its tread.

“Meridian plane” means a plane that contains the tire's axis of rotation.

“Radial” and “radially” are used to mean directions radially toward or away from the axis of rotation of the tire.

A “radial tire” means a belted or circumferentially restricted pneumatic tire in which at least one ply has cords which extend from bead core to bead core and are laid at cord angles between 65° and 90° with respect to the equatorial plane of the tire.

“Rim” means a support for a tire or a tire and tube assembly upon which the tire bead regions are seated. A rim typically comprises rim flanges on its axial extremities.

“Rim Flange Protector” means an annular projection in the rim flange contacting area of the bead region that extends the chafer to follow the axially outward curvature of the rim flange, and generally protrudes at least as far out in axial direction as the flange.

“Rubber” or “elastomer” are used as synonyms and include both natural rubber compound and synthetic rubber compound. Unless otherwise specified, “rubber” designates a cured rubber (typically obtained from unsaturated rubber by sulfur or non-sulfur vulcanization). The rubber need not be completely cured, i.e., its molecular chains may contain residual cure sites (e.g., allylic positions) available for crosslinking with other molecular chains. The expressions “rubber composition” “compounded rubber” and “rubber compound” may be used interchangeably to refer to rubber (elastomer) which has been blended or mixed with various ingredients and materials, e.g., reinforcing fillers, such as carbon black, precipitated amorphous silica, or the like, and then cured. Specific examples of rubbers include neoprene (polychloroprene), polybutadiene (e.g., cis-1,4-polybutadiene), polyisoprene (e.g., cis-1,4-polyisoprene), butyl rubber, halobutyl rubber (such as, e.g., chlorobutyl rubber or bromobutyl rubber), styrene/isoprene/butadiene rubber, copolymers of 1,3-butadiene or isoprene with monomers such as, e.g., styrene, acrylonitrile and methyl methacrylate. Other types of rubber include carboxylated rubber, silicon-coupled rubber, or tin-coupled star-branched polymers.

“Sidewall” designates the axially outer parts of a tire that provide protection for the carcass ply or plies and withstand flexing and weathering.

In the present document, the verb “to comprise” and the expression “to be comprised of” are used as open transitional phrases meaning “to include” or “to consist at least of”, not excluding the presence of further elements or components. Unless otherwise implied by context, the use of singular word form is intended to encompass the plural, except when the cardinal number “one” is used: “one” herein means “exactly one”. Ordinal numbers (“first”, “second”, etc.) are used herein to differentiate between different instances of a generic object; no particular order, importance or hierarchy is intended to be implied by the use of these expressions. Furthermore, when plural instances of an object are referred to by ordinal numbers, this does not necessarily mean that no other instances of that object are present (unless this follows clearly from context). When reference is made to “an embodiment”, “one embodiment”, “embodiments”, etc., this means that these embodiments may be combined with one another. Furthermore, the features of those embodiments can be used in the combination explicitly presented but also that the features can be combined across embodiments without departing from the invention, unless it follows from context that features cannot be combined.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of a pneumatic radial light truck tire10in accordance with an embodiment of the invention is illustrated inFIG.1. Pneumatic tire10is of generally open toroidal shape, of which the drawing shows only one quadrant in cross-section. Pneumatic tire10includes a tread12, a bead region14and a sidewall16extending from an edge (or shoulder) of the tread generally in a radially inward direction to the bead region14. The bead region includes a hexagonal bead core18, which serves to secure the tire10to a rim. The tire10further includes first and second carcass plies20,22, which extend between the axially separated bead cores and which confer the tire its generally open toroidal shape. The first and second carcass plies20,22are wrapped around the bead core18and terminate in respective turnup portions20a,22alocated in bead region14.

A first apex24is arranged in the bead region14, radially outwardly of the bead core18and between the main portions of the first and second carcass plies20,22on the one hand and the respective turnup portions20a,22aon the other hand. The first apex24serves as a filler that provides progressive transition from the rather stiff bead region into the more flexible sidewall portion. The first apex24tapers in radially outward direction. An apex extension26is arranged in the continuation of the first apex24in radially outward direction. Apex extension26may have the form of an annular strip apex or annular gumstrip. The radially inward end of the apex extension26may be arranged in abutment with the radially outward extremity of the first apex24or with some annular overlap with the first apex24. When the apex extension26and the first apex are arranged with an annular overlap, the radial extent of the overlap region is preferably kept relatively small compared to the radial extents of the apex extension26and the first apex24, e.g., below 30% of the radial extent of the first apex24.

The turnup portion of the first ply20, hereinafter the “first turnup portion20a”, extends along the axially outer side of the first apex24and along a part of the axially outer side of the apex extension26so as to terminate radially inwardly from the radially outward end28of the apex extension26. The turnup portion of the second ply22, hereinafter the “second turnup portion22a”, extends along the axially outer side of the first apex24and along a part of the axially outer side of the apex extension26. The second turnup portion22ais located axially inward from the first turnup portion20aand terminates radially inwardly both from the radially outward end28of the apex extension26and from the termination of the first turnup portion20a. In the illustrated embodiment, both the first turnup portion20aand the second turnup portion22athus are in direct contact with respective annular portions of the apex extension26.

The bead region14further comprises a chafer30positioned around at least a portion of the bead core18and the first and second turnup portions20a,22a. The chafer30may be comprised of one or more rubber components forming together a bead base32and a rim flange contacting area34. The bead base32forms the radially inner diameter of the bead region14and includes a toe guard36on its axially inner side. The bead base32and the rim flange contacting area34are joined via a region called the bead heel38. The rim flange contacting area34is terminated on its radially outer side by a rim flange protector40.

A second apex42is arranged between the chafer portion(s) forming the rim flange protector40and at least one of the first apex24and the apex extension26. In the illustrated embodiment, the second apex is sandwiched between the chafer and the turnup portions20a,22aof the carcass plies. The second apex42comprises a radially inward region tapering in radially inward direction, a radially outward region tapering in radially outward direction and a bulged transition region between the radially outward region and the radially inward region. The radially inward region of the second apex42generally follows the contour of the rim flange contacting area34while the bulged transition region is arranged axially inward from the rim flange protector40. The second apex42reinforces the transition region between the bead region14and the sidewall16. Together with the apex extension26and the turnup portions20a,22aof the plies, the second apex forms a multilayer reinforcement structure that provides sufficient stiffness to the transition region between the bead region14and the sidewall16and efficiently directs forces exerted on the tire10by the rim flange radially outwards.

Tread12is formed in the radially outer part of tire10. The zones in which the tread portion and the sidewalls meet are generally referred to as the shoulders or tread edges of the tire10. The tread12may be formed of a tread band, including one or more tread layers and a tread base. The tread12and rests on a belt package44, which provides stability to the tread12and prevents cuts or perforations in the tread band from reaching the carcass plies20,22.

FIG.2illustrates the construction of a reference point46for position coordinates in the bead region (and in the sidewall region). In each meridian cross-sectional plane of the tire, a reference point46may be defined as being located on the bead heel38, in a position that is closest to an intersection point of a straight-line continuation48of the bead base32and a straight-line continuation50of the flange contacting area34. Line52corresponds to the tangent of the bead heel in reference point46. By construction, reference point46corresponds to the orthogonal projection of the intersection point onto tangent52.

Table 1 below indicates preferred distances from the reference point46of selected elements of tire10:

In addition, the bead core preferably has a diameter of 6 to 12 mm, the first apex preferably has a base width in the range from 4 to 10 mm, and the second apex preferably has a thickness from 3 to 7 mm in the bulged transition region.

Table 2 indicates preferred gauges from the turnup portion of the first ply to the outer surface of the tire, at different distances from the reference point:

A second embodiment of a pneumatic radial light truck tire110in accordance with an embodiment of the invention is illustrated inFIG.3. Pneumatic tire110includes a tread112, a bead region114and a sidewall116extending from an edge (or shoulder) of the tread generally in a radially inward direction to the bead region114. The bead region includes a hexagonal bead core118, which serves to secure the tire110to a rim. The tire110further includes first and second carcass plies120,122, which extend between the axially separated bead cores and which confer the tire its generally open toroidal shape. The first carcass ply120is wrapped around the bead core118and terminates in a turnup portion120alocated in bead region114.

A first apex124is arranged in the bead region114, radially outwardly of the bead core118and between the main portion of the first carcass ply120on the one hand and the turnup portions120aon the other hand. The first apex124serves as a filler that provides progressive transition from the rather stiff bead region114into the more flexible sidewall portion. The first apex124tapers in radially outward direction. An apex extension126is arranged in the continuation of the first apex124in radially outward direction. Apex extension126may have the form of an annular strip apex or annular gumstrip. The radially inward end of the apex extension126may be arranged in abutment with the radially outward extremity of the first apex124or with some annular overlap with the first apex124. When the apex extension126and the first apex are arranged with an annular overlap, the radial extent of the overlap region is preferably kept relatively small compared to the radial extents of the apex extension126and the first apex124, e.g., below 30% of the radial extent of the first apex124.

The turnup portion120aof the first ply120, extends along the axially outer side of the first apex24and along a part of the axially outer side of the apex extension126so as to terminate radially inwardly from the radially outward end128of the apex extension126.

The second carcass ply122is arranged alongside the first ply120in the radially outer part of the sidewall portion but it parts from the first ply120at the radially outward end128of the apex extension126. From that point, the second carcass ply continues into the bead region114along the axially outer side of the apex extension124. More radially inward, the second carcass ply122meets the turnup portion120aof the first ply and then extends along the axially outer side of the turnup portion120aof the first ply, forming an overlap with it.

The bead region114further comprises a chafer130positioned around at least a portion of the bead core118and the turnup portions120a. The chafer130may be comprised of one or more rubber components forming together a bead base132and a rim flange contacting area134. The bead base132forms the radially inner diameter of the bead region114and includes a toc guard136on its axially inner side. The bead base132and the rim flange contacting area134are joined via the bead heel138. The rim flange contacting area134is terminated on its radially outer side by a rim flange protector140.

A second apex142is arranged between the chafer portion(s) forming the rim flange protector140and at least one of the first apex124and the apex extension126. In the illustrated embodiment, the second apex142is sandwiched on one side by the chafer130and on the other side by the turnup portion120aand the second ply122. The second apex142comprises a radially inward region tapering in radially inward direction, a radially outward region tapering in radially outward direction and a bulged transition region between the radially outward region and the radially inward region. The radially inward region of the second apex142generally follows the contour of the rim flange contacting area134while the bulged transition region is arranged axially inward from the rim flange protector140. The second apex142reinforces the transition region between the bead region114and the sidewall116. Together with the apex extension126, the turnup portion120aand the second ply122, the second apex142forms a multilayer reinforcement structure that provides sufficient stiffness to the transition region between the bead region114and the sidewall116and efficiently directs forces exerted on the tire110by the rim flange radially outwards.

Tread112is formed in the radially outer part of tire110. The zones in which the tread portion and the sidewalls meet are generally referred to as the shoulders or tread edges of the tire110. The tread112may be formed of a tread band, including one or more tread layers and a tread base. The tread112and rests on a belt package144, which provides stability to the tread112and prevents cuts or perforations in the tread band from reaching the carcass plies120,122.

A reference point146for position coordinates in the bead region (and in the sidewall region) is constructed in the same way as illustrated inFIG.2.

Table 3 below indicates preferred distances from the reference point146of selected elements of tire110:

TABLE 3Distance fromTire elementreference pointEnding of the turnup portion of 1st ply25 to 110 mmEnding of 2nd ply0 to 20 mmRadially outward end of 1st apex10 to 40 mmRadially inward end of apex extension5 to 40 mmRadially outward end of apex extension35 to 120 mmRadially inward end of 2nd apex5 to 25 mmRadially outward end of 2nd apex30 to 70 mm

In addition, the bead core preferably has a diameter of 6 to 12 mm, the first apex preferably has a base width in the range from 4 to 10 mm, and the second apex preferably has a thickness from 3 to 7 mm in the bulged transition region.

Table 4 indicates preferred gauges from the second ply to the outer surface of the tire, at different distances from the reference point: