Sumitomo Rubber Industries Limited

The Goodyear & Tire Rubber Company

Mitsuharu Koya

Yoshiyuki Takada

Toshio Koyama

Minoru Nishi

Naoki Kageyama

Satoshi Tsuda

Fumihiro Tsubono

Takeshi Kuroki

Yoshiki Kanaya

Takahiro Kimishima

Masakazu Washizuka

Koji Mori

Jyunji Ohira

Masaru Araki

A heavy-duty pneumatic tire includes a section width being equal to or less than 335 mm, an aspect ratio being equal to or less than 55%, and a toroidal carcass extending between axially spaced bead portions through a tread portion and sidewall portions. The carcass includes a carcass ply which includes a main portion and a turn-up portion turned up around a bead core of each bead portion. A belt layer is disposed radially outward of the carcass in the tread portion, wherein a radially outer end of the turn-up portion is located between the main portion and the belt layer in the tread portion. A sheeted rubber layer is disposed between the main portion and the turn-up portions in each sidewall portion.

Heavy-duty pneumatic tire

A pneumatic tire comprises a tread portion provided with sipes, the sipes each having a zigzag configuration at any depth from the top of the sipe to a certain depth, and the zigzag configuration having vertexes Qon one side of the zigzag and vertexes Qon the other side of the zigzag, wherein as the depth increases from the top of the sipe to said certain depth, the vertexes Qshift in the longitudinal direction of the sipe and the direction of the shift is turned at least once such that the vertexes Qfirst shift towards one direction then towards the other direction, thereby describing a zigzag line extending from the top of the sipe to said certain depth and having at least one tuning point, but the vertexes Qdescribe lines which are linear or less zigzag when compared with the zigzag lines described by the vertexes Q

Pneumatic tire with tread having zigzag sipes

In a ground-contact surface shape of a tire, when a tangent angle formed between an axial direction of the tire and a tangent X at each point P on a profile line of the tire is defined as &#x3b8;, a tangent angle &#x3b8;in a ground-contact end point Pd is 25&#xb0; or smaller. When a minimum value of the tangent angle &#x3b8; in a region Y which is separated away from a tire equator C by a distance in a range of not less than 0.4 times but not more than 0.7 times a half of the ground-contact width of the tread is defined as &#x3b8;, and a tangent angle at a 0.9 times point Pq which is separated away from the tire equator C by a distance of 0.9 times the half of the ground-contact width of the tread is defined as &#x3b8;, a difference (&#x3b8;) is set in a range of not less than &#x2212;10&#xb0; but not more than +10&#xb0;.

Heavy-duty tire having ground-contact surface shape

A pneumatic tire comprises a tread portion provided with blocks, the blocks are axially divided by at least one circumferential groove and circumferentially divided by oblique grooves inclined with respect to the tire axial direction towards one direction, and each of the blocks is subdivided into at least two parallelogrammic block elements by at least one open sipe extending across the block and inclined with respect to the tire axial direction towards the same direction as the oblique grooves, the parallelogrammic block elements include two block-end elements located on the circumferential ends of the block, and each of the block-end elements is provided with at least one closed sipe extending at an angle of less than 45 degrees with respect to the tire axial direction and terminating within the block to have closed ends.

Pneumatic tire with tread including blocks having open and closed sipes

Tire tread

A pneumatic tire to be mounted on a 15-degree-taper rim comprises a pair of bead portions each with a bead core, wherein in a meridian section of the tire under a state that the tire is not mounted on the rim but the bead portions are held such that the bead width is equal to the rim width of the 15-degree-taper rim, the bead base surface of each bead portion, which is defined as extending between a bead heel and a bead toe, is substantially straight and inclined at an angle of from 22 to 26 degrees with respect to the tire axial direction, and a ratio La/Lb of the axial width La of the bead base surface to the maximum width Lb of the bead core is in a range of from 1.3 to 1.6.

Pneumatic tire with specified bead base surface

A heavy duty pneumatic tire comprises a tread portion which is provide with wide circumferential grooves having a width Wm,of 4.0 mm to 20.0 mm and narrow circumferential grooves having a width Wm,of not less than 2.0 mm but less than 4.0 mm, and each region which is defined between one of the wide circumferential grooves and the axially adjacent narrow circumferential groove is provided with axial grooves extending from the wide circumferential groove to the narrow circumferential groove to circumferentially divide the region into blocks, wherein the axial grooves include variable-width grooves of which groove width increases from the wide circumferential groove to the narrow circumferential groove.

Heavy duty pneumatic tire including variable width grooves and constant width grooves

A pneumatic tire comprises an improved tread portion provided with blocks, each block provided with a sipe, the sipe extending across the block to have a first open end and a second open end, the sipe comprising three components forming a generally Z-shaped configuration, whereby the two parts divided by the sipe are engaged with each other to increase the block rigidity.

Growing community of inventors

Kobe, Japan

Mitsuharu Koya