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JP-2026075909-A - Lug tires

JP2026075909AJP 2026075909 AJP2026075909 AJP 2026075909AJP-2026075909-A

Abstract

[Problem] To provide a lug-equipped tire 2 that suppresses the temperature rise of the lugs 16, suppresses the adhesion of mud, and allows the mud to be easily removed even if it does adhere. [Solution] The tire 2 is equipped with a tread 6. The tread 6 is equipped with a plurality of lugs 16. Each lug 16 is equipped with a plurality of steps 42 on its side surface 22. Each step 42 is equipped with a stepped portion 44 and a stepped plate portion 46. Of the plurality of steps 42, the edge SGs of the outermost step 42s located radially outward is located axially outward from the protruding reference line LWE, and the starting point SSu of the innermost step 42u located radially inward is located axially inward from the protruding reference line LWE. The edge SG of the step 42 is inclined with respect to the circumferential direction. The tip Gh of the edge SG located on the rotational direction leading side is located radially inward from the rear end Gt of the edge SG located on the rotational direction trailing side. [Selection Diagram] Figure 1

Inventors

  • 松井 美咲

Assignees

  • 住友ゴム工業株式会社

Dates

Publication Date
20260511
Application Date
20241023

Claims (7)

  1. A tire comprising a pair of beads, a carcass spanning the pair of beads, a tread located radially outward of the carcass, and a pair of sidewalls located axially outward of the carcass, The tread comprises a plurality of lugs separated by grooves and arranged in the circumferential direction, Each of the lugs protrudes from the bottom of the groove, The lug comprises a leading end located on the equatorial plane of the tire and a rear end located on the edge of the tread and having a side surface of the lug, When the tire moves forward, the leading edge is positioned towards the front end in the direction of rotation, and the rear end is positioned towards the rear end in the direction of rotation. The lug has a plurality of steps arranged radially on its side surface, Each of the aforementioned steps comprises a stepped portion and a stepped plate portion located radially outward from the stepped portion, The axial inner end of the stepped portion is the starting point of the step. The boundary between the stepped portion and the stepped plate portion is the edge of the step. The straight line passing through the edge of the tread and the position on the outer surface of the tire corresponding to the maximum width position of the carcass is the protruding reference line. Of the multiple steps, the edge of the outermost step located radially outward is located axially outward from the protruding reference line, and the starting point of the innermost step located radially inward is located axially inward from the protruding reference line. The edge of the aforementioned step is inclined with respect to the circumferential direction, The tip of the edge located on the side that arrives first in the direction of rotation is located radially inward from the rear end of the edge located on the side that arrives second in the direction of rotation. Lug tires.
  2. The ratio of the thickness of the tread to the width of the tread at the edge of the outermost step is 10% or more and 25% or less. A lugged tire as described in claim 1.
  3. The angle of the corner including the starting point of the aforementioned step is 90 degrees or more and 150 degrees or less. A lugged tire as described in claim 1.
  4. The ratio of the length of the stepped portion to the thickness of the tread at the edge of the outermost step is 15% or more and 30% or less. A lugged tire as described in claim 1.
  5. At the rear end of the edge of the step, the angle that the edge makes with respect to the circumferential direction is 10 degrees or more and 70 degrees or less. A lugged tire as described in claim 1.
  6. The corner including the starting point of the step and the corner including the edge of the step are rounded. A lugged tire as described in claim 1.
  7. It is for agricultural machinery. A lugged tire according to any one of claims 1 to 6.

Description

This invention relates to lugged tires. The tread of a lugged tire features multiple lugs separated by grooves. The lugs protrude from the bottom of the grooves. These lugs contribute to traction. Work machinery such as agricultural and construction vehicles travel on unpaved roads, including wet fields and uneven terrain. To achieve high traction, these work machines are fitted with lugged tires. Lugged tires travel through muddy terrain, causing mud to adhere to the tire treads. After completing a task, the machinery, for example, travels on paved roads to move to the next work site. When mud remains on the tires while traveling on paved roads, the mud falls off, contaminating the roads. To prevent mud from contaminating paved roads, there is a need for tires that resist mud adhesion or tires that allow mud to be easily removed if it does adhere. Patent Document 1 below proposes providing a group of protrusions on the bottom of the rug to suppress the adhesion of mud. Japanese Patent Publication No. 2017-065436 This is an exploded view showing a portion of the tread surface of a lugged tire according to one embodiment of the present invention.This is a cross-sectional view along the line II-II in Figure 1.This is a plan view showing a portion of the side of the tire in Figure 1.This is a cross-sectional view along the line IV-IV in Figure 3.This is a cross-sectional view showing a modified step. The present invention will now be described in detail, with reference to the drawings as appropriate, based on preferred embodiments. The tire of this invention is mounted on a rim. Air is filled inside the tire, and the internal pressure of the tire is regulated. A tire mounted on a rim is also called a tire-rim assembly. A tire-rim assembly comprises a rim and a tire mounted on this rim. In this invention, the state in which a tire is mounted on a standard rim, the internal pressure of the tire is adjusted to the standard internal pressure, and no load is applied to the tire is referred to as the "standard state." In this invention, unless otherwise specified, the dimensions and angles of each part of the tire are measured under normal conditions. The dimensions and angles of each part of the tire in the meridional cross-section, which cannot be measured when the tire is mounted on a standard rim, are measured at the tire's cross-section, obtained by cutting the tire along a plane containing the axis of rotation. In this measurement, the tire is set so that the distance between the left and right beads matches the distance between the beads in a tire mounted on a standard rim. The tire's structure, which cannot be confirmed when the tire is mounted on a standard rim, is confirmed at the aforementioned cross-section. A "standard rim" refers to a rim defined in the tire's specifications. The "standard rim" in the JATMA standard, the "Design Rim" in the TRA standard, and the "Measuring Rim" in the ETRTO standard are all considered standard rims. Standard tire pressure refers to the internal pressure specified in the tire's respective standard. The "maximum air pressure" in the JATMA standard, the "maximum value" listed in the TRA standard's "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and the "INFLATION PRESSURE" in the ETRTO standard are all considered standard tire pressures. The standard load refers to the load specified in the tire's specifications. The "maximum load capacity" in the JATMA standard, the "maximum value" listed in the TRA standard's "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and the "LOAD CAPACITY" in the ETRTO standard are all considered standard loads. In this invention, the tread portion of a tire is the part of the tire that makes contact with the road surface. The bead portion is the part of the tire that is fitted onto the rim. The sidewall portion is the part of the tire that spans the space between the tread portion and the bead portion. The tire comprises the tread portion, a pair of bead portions, and a pair of sidewall portions. The tread portion is the part that includes the tread as a component. The sidewall portion is the part that includes the sidewall as a component. The bead portion is the part that includes the bead as a component. [Practical knowledge that formed the basis of this invention] In soft, moist fields, lugged tires will sink into the mud as they drive. Therefore, mud accumulation is unavoidable. The repeated deformation and recovery of rubber generates heat. Lugs are raised ridges that extend from the equatorial plane towards the edge of the tread. The lug height is greatest at the edge of the tread. The higher the lug height, the larger the volume of the lug. Lugs with high lug height tend to get hotter. In many cases, indentations are provided on the sides of the lugs to suppress the temperature rise. The recesses have a structure that is surrounded by walls, like a window frame. As mentioned earlier, lugged tires travel while buried in mud