Sumitomo Rubber Industries Limited

Shinichi Matsuura

Satoshi Tsuda

Kenji Tagashira

A pneumatic tireincludes a tread, a pair of sidewalls, a pair of beads, and a carcass. In the pair of beads, each beadincludes a coreand a bead fillerextending outward from the corein the radial direction. A minimal value &#x3b8;a of the inclination angle of the bead filleris greater than or equal to 30 degrees, and is not greater than 44 degrees. A ratio Wa/Wb of a width Wa of the bead fillerto a width Wb of a bead portion is greater than or equal to 0.30, and is not greater than 0.45.

Pneumatic tire

A method for alarming decrease in tire air-pressure, which detects decrease in internal pressure of a tire attached to a vehicle and accordingly issues alarm. The method includes the steps of: detecting rotational information of the respective tires; storing the rotational information of the respective tires; displaying a summer tire, a winter tire and a run-flat tire; designating a currently attached tire from among the displayed tires and switching to a threshold for judging decrease in internal pressure which matches the tire; judging decrease in internal pressure of a tire by using the threshold; and issuing an alarm on the basis of the judgment of the judging means. Since thresholds which match tires can be suitably switched when the driver operates the touch panel for discriminating presently mounted tires, it is possible to eliminate erroneous alarm and to perform judgment of decompression at even higher accuracy.

Method and apparatus for alarming decrease in tire air-pressure and threshold changing program

A method of judging a vehicle loading condition includes detecting rotational speeds of wheels mounted on a vehicle, calculating a judging value of tire pressures based on the difference of the sum of rotational speeds of two pairs of wheels located at the opposing corners of the vehicle and detecting an acceleration to a lateral direction of the vehicle. The loading state of the vehicle is judged by the change of a primary coefficient based on an approximated relation between the acceleration to a lateral direction and the judging value of the tire pressures. A tire deflation warning system detects the stop of the vehicle, and the air pressure of four wheels is judged not to be decreased if the loading condition of a vehicle is changed more than a fixed value before and after a vehicle stop. The tire deflation warning system can prevent a deflation alarm for a vehicle with a heavy load.

Judging method of vehicle loading condition

A heavy duty tire comprises a pair of axially outermost circumferential rows of shoulder blocks, each of the shoulder blocks provided with a circumferentially extending narrow groove, the narrow groove subdividing the shoulder block into an axially inner wide main part and an axially outer narrow lateral part, and the narrow groove is curved convexly so that the narrow lateral part is narrower in a middle region than both the circumferential end regions, whereby the heel and toe wear and shoulder wear and resistance to tear-off can be improved.

Heavy duty tire including narrow groove

A pneumatic tire comprises a central longitudinal groove in a tread crown region and an outer longitudinal groove in each tread shoulder region, the longitudinal grooves are crossed by lateral grooves to form crossings and to define blocks on each side of each longitudinal groove, the outer longitudinal grooves are provided near the crossings with tie-bars, the length Tc of each of which is 10 to 40% of the average length of the longitudinal edges of two blocks axially adjacent to the tie-bar, each length measured along the longitudinal groove. Preferably, the lateral grooves in the crown region provided near the crossings with tie-bars, the length Ta of each of which is 10 to 40% of the average length of the lateral edges of two blocks circumferentially adjacent to the tie-bar, each length measured along the lateral groove.

Pneumatic tire including tie bars

The invention is directed to a pneumatic tire that can be mounted on a rim (wheel) to assure good engagement with the rim while preventing the occurrence of rim offsets. The bead portion 4a (as indicated by a solid line in FIG. 1) on the front side of a tire 1 which is later mounted on the rim has a bead base diameter .phi..sub.1, a toe portion angle .phi..sub.1, a contact angle .alpha..sub.1 , and a heel portion radius R.sub.1, whereas the bead portion 4b (as indicated by a dashed line in FIG. 1) on the back side of the tire which is first mounted on the rim has a bead base diameter .phi..sub.2, a toe portion angle .theta..sub.2, a contact angle .alpha..sub.2 and a heel portion radius R.sub.2. The bead portion 4a on the front side has a different shape than the bead portion 4b on the back side and the following two relationships hold between the two bead portions; the angle of .theta..sub.2 of the toe portion on the back side should be greater than the angle .theta..sub.1 of the toe portion on the front side, with the difference between the two angles being not more than 4.degree. (4.degree..gtoreq..theta..sub.2 -.theta..sub.1 &gt;0.degree.); and the bead base diameter .phi..sub.2 on the back side should be greater than the bead base diameter .phi..sub.1 on the front side (.phi..sub.2 &gt;.phi..sub.1); preferably, the difference between the bead base diameters on the two sides (.phi..sub.2 -.phi..sub.1) is 2 mm or less (.phi..sub.2 -.phi..sub.1 .ltoreq.2 mm).

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Kobe, Japan

Shinichi Matsuura