Low rolling resistance pneumatic tire

Abstract

The utility model relates to a low-rolling-resistance pneumatic tire which is provided with a tread, and a circumferential groove is formed in the tread. Each circumferential groove is provided with a notch groove, a thin groove and a water storage groove which are sequentially formed from the tire surface to the interior of the tire body; the maximum widths of the notch groove, the thin groove and the water storage tank in the axial direction of the tire are marked as W1, W2 and W3 respectively, and at least W2lt is met; w1 and W2lt; w3. According to the low-rolling-resistance pneumatic tire, the three-section groove design of the notches, the thin grooves and the water storage grooves is adopted in the radial direction of the tire through the central circumferential groove, and parameters such as the width, the depth and the repeated spacing are reasonably configured for the three-section groove design, so that it is ensured that the tire has excellent wet land performance, low-rolling-resistance performance and stone clamping prevention performance.

Description

Technical Field

[0001] The utility model relates to the technical field of tires, and particularly relates to a low-rolling-resistance pneumatic tire. Background Art

[0002] Typical tires for buses or trucks will encounter various road conditions (e.g., dry / wet roads, roads with gravel, etc.) during their use. Different road conditions have different performance requirements for the tires. In order to match different use environments of the tires, tire tread patterns are designed with different characteristics according to different performance requirements of the tires. For example, in order to improve the wet performance of pneumatic tires, the width of circumferential grooves can be increased. However, simply increasing the width of circumferential grooves will reduce the stiffness of the tread surface. This reduction in stiffness may have an adverse impact on the performance of the tires such as low-rolling-resistance performance and wear, and at the same time, it will increase the risk of stone trapping in the tires. Therefore, the wet performance, rolling resistance, stone-trapping prevention and other performances of the tires often restrict each other. Therefore, manufacturing a tire that兼顾湿地性能、低滚阻性能且防夹石子的轮胎 is a technical problem in the current tire industry.

[0003] To solve the above background problems, more and more companies have carried out novel feature designs on the grooves of tires to improve the performance of tires. Utility modelers such as Goodyear have set stability grooves in the circumferential direction of the tires to improve the cornering stiffness of the tires and reduce groove bottom cracking; utility modelers such as Michelin have set hidden grooves and partially hidden grooves in the circumferential direction of the tires to balance the wet performance and wear performance of the tires. The above existing tire designs do not balance multiple performances such as the wet performance, low-rolling-resistance performance, handling performance, and stone-trapping prevention of the tires. To solve the above technical problems, the utility model provides a pneumatic tire. By adopting a three-stage groove design in the radial direction of the tire through a central groove, and at the same time, the cut of the three-stage groove is designed in a gradient manner on the circumferential surface of the tire, so as to ensure that the tire has stone-trapping prevention, low-rolling-resistance and excellent handling performance while improving the wet performance of the tire. Summary of the Utility Model

[0004] To balance multiple performances of the tire, the utility model provides a low-rolling-resistance pneumatic tire.

[0005] The present application provides a low-rolling-resistance pneumatic tire, which is characterized in that it has a tread surface, and circumferential grooves are formed on the tread surface; several circumferential grooves have incision grooves, fine grooves and water storage grooves formed in sequence from the tread surface to the inside of the tire body;

[0006] The maximum widths of the incision groove, the fine groove and the water storage groove along the axial direction of the tire are respectively denoted as W1, W2 and W3, and at least W2 < W1 and W2 < W3 are satisfied.

[0007] It should be noted that there is an unclear expression "兼顾湿地性能、低滚阻性能且防夹石子的轮胎" in the original text. It is recommended to check and clarify this part for a more accurate translation.Preferably, the widths of the notched groove, the fine groove, and the water storage tank satisfy: 4mm≤W1≤20mm, and 2.5mm≤W3≤16mm.

[0008] Preferably, the notch has a periodically varying opening width along the circumferential direction on the tread surface, wherein the periodic spacing L satisfies 0.5PL≤L≤4PL;

[0009] Preferably, 1.0PL≤L≤2.2PL.

[0010] Preferably, the widths of the notch at its widest and narrowest points are denoted as W1max and W1min, respectively, and both satisfy 0.3mm≤(W1max-W1min) / 2≤6mm;

[0011] Preferably, 1.5mm ≤ (W1max - W1min) / 2 ≤ 5mm.

[0012] Preferably, the notch forms a pair of opposing notch sidewalls, and the opposing notch sidewalls form a non-zero included angle α, where 20°≤α≤120°;

[0013] Preferably, 42.5°≤α≤85°

[0014] Preferably, the width of the fine groove satisfies: 0.5mm≤W2≤3.0mm.

[0015] Preferably, the water storage tank has opposing water storage walls, and the two opposing water storage walls form an angle δ inside the tire body. The intersection of the water storage walls occurs inside the tire tread, wherein 30°≤δ≤125°.

[0016] Preferably, the depths of the notched groove, the fine groove, and the water storage tank are denoted as h1, h2, and h3, respectively; wherein h1, h2, and h3 satisfy: h1 + h2 + h3 = H, 0.08H ≤ h1 ≤ 0.41H, 0.15H ≤ h2 ≤ 0.55H, and 0.25H ≤ h3 ≤ 0.60H; where H is the total depth of the circumferential groove.

[0017] Preferably, the bottom of the water storage tank has a stone-throwing device that extends above the bottom of the water storage tank;

[0018] Preferably, the width W4 of the stone-throwing device satisfies 1mm≤W4≤0.4W3; the depth W4 of the stone-throwing device satisfies 1mm≤h4≤0.7h3.

[0019] Preferably, it also includes transverse sipes formed on the tire tread, the transverse sipes extending from the circumferential groove to both sides of the circumferential groove on the tire tread; different transverse sipes are staggered or connected on the tire tread; preferably, the transverse sipes are inclined along the tire circumference.

[0020] The low rolling resistance pneumatic tire of this application utilizes a three-section groove design in the radial direction of the tire, consisting of a central circumferential groove, a slit, a fine groove, and a water reservoir. By rationally configuring parameters such as width, depth, and repeatability spacing of the three-section groove design, and combining the gradual width design of the slits on the circumferential surface of the tire, the tire is ensured to have excellent wet performance, low rolling resistance, and anti-stone trapping performance. Attached Figure Description

[0021] Figure 1 This is a schematic diagram showing the unfolded tread 11 of the low rolling resistance pneumatic tire of this application;

[0022] Figure 2 This is a schematic diagram of the radial cross-section of the main groove 121 of the low rolling resistance pneumatic tire of this application;

[0023] Figure 3 This is a schematic diagram showing the circumferential unfolding of the notch 211 of the low rolling resistance pneumatic tire of this application;

[0024] Figure 4 This is a schematic diagram of the radial cross-section of the tread 11 of the low rolling resistance pneumatic tire of this application.

[0025] Figure 5 This is a schematic diagram of other gradient forms of the tread 11 of the low rolling resistance pneumatic tire of this application;

[0026] Figure 6 This is a schematic diagram of another cross-sectional embodiment of the tread 11 of the low rolling resistance pneumatic tire of this application.

[0027] In the picture:

[0028] 1: Tire; 11: Tread; 12: Circumferential groove; 121: Main groove; 122: Shoulder groove; 13: Cross groove; 14: Tread block; 211: Cut groove; 212: Fine groove; 213: Water tank; 215: Stone projectile; 216: Bottom of water tank; 217: Water tank wall; 218: Middle wall; 219: Cut sidewall. Detailed Implementation

[0029] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. In this specification, the dimensions of the drawings do not represent the actual dimensions. They are only used to illustrate the relative positional and connection relationships between the components. Components with the same name or the same reference numeral represent similar or identical structures and are limited to illustrative purposes.

[0030] The following terms have the meanings applicable to the technical solutions described in this application.

[0031] Circumferential direction of the tire: refers to the direction along the circumference of the tire, that is, the direction around the axis of rotation of the tire;

[0032] Tire axial direction: refers to the direction along the tire's axis of rotation, also known as the tire width direction;

[0033] Tire radial direction: refers to the direction along the circumference radius of the tire, that is, the direction of the tread groove depth; in the radial direction, the direction in which a point on the circumference surface of the tire penetrates into the center of the tire's rotation is defined as the positive radial direction, and the opposite is the negative radial direction;

[0034] Tread X-direction: i.e., the tire axis mentioned above;

[0035] Tread Y-direction: The direction corresponding to the tire circumference after the tread is flattened;

[0036] Radial section: The tire cross section obtained by cutting along the plane formed by the tire axis and a certain radial direction;

[0037] Circumferential groove: A groove that extends circumferentially on the tire tread.

[0038] Transverse groove: A narrow groove that extends along the axial direction of the tire tread.

[0039] Tread pitch: The distance between adjacent lateral sipes on the tire circumferential direction, denoted as PL.

[0040] Figure 1 This is a schematic diagram of the structure of the low rolling resistance pneumatic tire of this application. This type of low rolling resistance pneumatic tire is mainly used in buses and trucks. The tire 1 has a tread 11, and circumferential grooves 12 and lateral grooves 13 are formed on the tread 11. The circumferential grooves 12 and lateral grooves 13 divide the tread 11 into different tread blocks 14.

[0041] exist Figure 1 In the illustrated embodiment, the circumferential groove 12 is further divided into shoulder grooves 122 located on the tread 11 closer to each side of the tire shoulder. Since the tire shoulder is located on both sides of the tread, the shoulder grooves 122 are formed on both sides of the tread 11, and there may be at least one shoulder groove 122 on each side. At least one main groove 121 is formed on the tread between the shoulder grooves 122 on both sides.

[0042] The transverse groove 13 extends from the circumferential groove 12 to both sides of the circumferential groove 12 on the tire tread. Different transverse grooves 13 may be staggered or connected on the tire tread. The transverse groove 13 is preferably inclined in the circumferential direction of the tire, that is, it is not at a right angle to the circumferential groove 12, but forms an acute angle, and the orientation of the acute angle is related to the tire's driving direction.

[0043] In order to improve the overall performance of the tire, this application mainly redesigns the circumferential groove 12, especially the main groove 121.

[0044] Figure 2It is a schematic diagram of the radial section of the main groove 121. The main groove 121 has a three-section groove structure that extends into the carcass below the tread in the positive radial direction. Specifically, the main groove 121 is successively formed with a cut groove 211, a fine groove 212, and a water storage groove 213 from the tread towards the inside of the carcass. The maximum widths of the cut groove 211, the fine groove 212, and the water storage groove 213 along the axial direction of the tire are denoted as W1, W2, and W3 respectively, and at least W2 < W1 and W2 < W3 are satisfied. In other words, the main groove 121 is dumbbell-shaped with wider ends and a narrower middle on the radial section.

[0045] The cut groove 211 is provided to prevent the curling effect of the groove edge when the tire turns, and at the same time has a certain water storage function to improve the handling performance and wet performance of the tire; when the tire is loaded, the opposite walls 218 of the fine groove 212 come into contact with each other to provide mutual deformation support, reduce strain, and lower the rolling resistance; while ensuring the handling performance and rolling resistance performance of the tire, the water storage groove 213 is provided to additionally provide a water storage volume to ensure the wet performance of the tire throughout its life cycle.

[0046] Among them, 4 mm ≤ W1 ≤ 20 mm. In order to simultaneously take into account the dry and wet braking and handling performance of the tire, it is preferably 4 mm ≤ W1 ≤ 10 mm; 0.5 mm ≤ W2 ≤ 3 mm. In order to simultaneously take into account the rolling resistance performance of the tire and the service life of the mold, it is preferably 1 mm ≤ W2 ≤ 2.2 mm; 2.5 mm ≤ W3 ≤ 16 mm. In order to take into account the wet performance of the tire, reduce the difficulty of vulcanization demolding, and at the same time avoid the stress concentration at the bottom of the water storage groove causing tearing at the groove bottom, it is preferably 5 mm ≤ W3 ≤ 10 mm.

[0047] With the depths of the slit groove 211, fine groove 212, and water reservoir 213 remaining constant (and their lengths also constant), when W1 < 4 mm, W1 is too small. During dry braking and handling, this easily leads to curling deformation at the edges of the circumferential grooves, reducing the effective contact area and thus negatively impacting dry braking and handling performance. Simultaneously, a smaller W1 reduces the groove volume in the slit groove area, preventing effective water storage and rapid drainage during wet braking and handling, increasing the risk of hydroplaning and affecting wet performance, while also creating traffic safety hazards. When W1 > 20 mm, W1 is too large, resulting in insufficient rigidity of the central tread pattern. The pressure distribution of truck and bus tires is usually high in the middle and low in the shoulder. When the tread block stiffness in the middle area of ​​the high-stress zone is too weak, it will first cause the tire to produce greater tread block compression deformation during normal driving, resulting in greater energy loss and adverse effects on rolling resistance. In addition, the excessively weak tread block stiffness in the middle of the tire will cause the tire to be more prone to greater shear and bending deformation during driving or steering, which will be detrimental to the tire's dry and wet braking and handling performance. At the same time, the excessively weak tread block stiffness in the middle of the tire will increase the stress and strain of the tire when it touches the ground, and the amount of tread slip will also increase, resulting in abnormal wear in the middle of the tire. Moreover, the fine grooves (212) will deform during the tire rolling process and thus achieve self-contact, that is, self-contact between the two side walls. This self-contact process, in turn, restricts the deformation of the tire's rubber blocks, thereby achieving the effect of reducing rolling resistance.

[0048] To further optimize tire performance, the slit groove 211 features a periodically varying width in the circumferential direction of the tread surface, with a periodic interval of 0.5PL≤L≤4PL, and preferably 1.0PL≤L≤2.2PL. This varying width design of the slit groove 211 in the circumferential direction of the tread surface not only ensures low rolling resistance but also optimizes the tire's wet performance and stone trapping resistance. Its mechanism of action is as follows: Compared with the constant width design, the gradient width design can provide effective grip on the groove boundaries in both the circumferential and axial directions of the tire, improving the tire's wet braking performance while ensuring wet handling performance. Regarding stone-throwing performance, the constant width design generates an upward force perpendicular to the sidewall plane of the cut, and this force is unidirectional, essentially parallel to the tire's radial tangent. In contrast, the gradient groove design, due to the curved sidewall plane of the cut, can generate multi-directional stone-throwing forces. Simultaneously, through the combined action of the groove walls on both sides of the cut, it can generate a torque in a counterclockwise or clockwise direction with the tire's radial direction as the rotation centerline, significantly increasing the probability of stone-throwing and thus improving the tire's stone-throwing performance. In terms of rolling resistance, compared with the constant width design, the gradient design only involves alternating widths, and through a reasonable width-to-width ratio optimization, it does not affect the actual rubber block volume. Therefore, its rolling resistance performance is not inferior to the constant width design.

[0049] like Figure 3 As shown, the widths (distance along the tire axial direction of the groove) of the widest and narrowest points of the slit groove 211 are denoted as W1max and W1min, respectively. The following relationship exists between them: 0.3mm ≤ (W1max - W1min) / 2 ≤ 6mm, and preferably 1.5mm ≤ (W1max - W1min) / 2 ≤ 5mm. When (W1max - W1min) / 2 > 6mm, this is too large, causing uneven stress on the tread blocks in the transition area. This results in uneven wear at the narrowest point of the slit and a tendency for stones to be trapped at the widest point.

[0050] like Figure 3 As shown, the transition arcs connecting the widest and narrowest points of the cut groove 211 are denoted as Re and Rc, respectively. They are related as follows: 0.5mm ≤ Rc ≤ Re ≤ 6.5mm, and preferably 2.0mm ≤ Rc ≤ Re ≤ 4.6mm. When Rc ≤ Re < 0.5mm, stress concentration is likely to occur in the transition area from the widest to the narrowest point of the cut, affecting tire life. When Re ≥ Rc > 6.5mm, the transition area from the widest to the narrowest point of the cut will be large, affecting the appearance of the tread pattern.

[0051] The width of the slit groove 211 on the tread surface is designed with a gradient, and the top view of the central circumferential groove is not limited to... Figure 1 As shown, it can also be replaced with Figure 5 Any shape is acceptable. The slit groove 211 forms a pair of opposing slit sidewalls 219 on the tread pattern. The opposing slit sidewalls 219 form a non-zero included angle α, and the intersection of the slit sidewalls 219 occurs inside the tread, where 20°≤α≤120°, and preferably 42.5°≤α≤85°, which can effectively increase the edge pressure on the tread. The cross-sectional shape of the slit groove 211 in the radial direction of the tire is not limited to... Figure 3 The triangle shown can also be replaced with Figure 5 The polygon shown.

[0052] The fine grooves 212 are channels of approximately equal width, defined by substantially parallel intermediate walls 218. When the distance W2 between these opposing walls is greater than 3.0 mm, W2 is too large. In this case, the fine grooves do not provide sufficient reinforcement to the tread blocks, preventing the tread blocks from self-contacting during tire rolling. This results in insufficient overall rigidity of the tread blocks and increases rolling resistance. Furthermore, increasing the volume of the fine grooves reduces the volume of the tread blocks, which is detrimental to tire wear performance.

[0053] When the tire axial width W3 > 16 mm, the tire is difficult to demold during manufacturing, and tread block tearing is likely to occur. When W3 < 2.5 mm, the water storage capacity of the water tank is insufficient, affecting the tire's wet performance.

[0054] The water reservoir 213 forms a pair of water-retaining walls 217 between adjacent tread blocks. The water-retaining walls 217 are connected to the bottom 216 of the water reservoir by an arc, the radius Ra of which is between 0.4 mm and 5 mm, preferably 1.2 mm ≤ Ra ≤ 2.5 mm. When Ra > 5 mm, the tire's water storage and drainage capacity on wet roads decreases, impairing the tire's wet performance. When the tire wears to a certain extent, it cannot guarantee sufficient wet traction. When Ra < 0.4 mm, stress concentration easily occurs at the arc connecting the water-retaining walls 217 and the bottom 216 of the water reservoir during driving, affecting the tire's service life. The opposing water-retaining walls 217 form a non-zero angle δ in the tire axial direction. The intersection of these opposing walls occurs inside the tread, where 30° ≤ δ ≤ 125°. When δ > 125°, demolding during tire manufacturing is difficult, easily causing tearing of the tread blocks.

[0055] The shape of the cross-section of the water tank 213 in the radial direction of the tire is not limited to... Figure 3 As shown, it can also be replaced with Figure 6 The cross-sectional shape shown.

[0056] We conducted experimental research on the above design scheme, and the experimental scheme and test results are shown in Table 1. Among them, the rolling resistance index was obtained by testing with an indoor rolling resistance testing machine, and the wet grip index, anti-stone trapping index and anti-eccentric wear index were obtained by FEA simulation.

[0057] Table 1

[0058]

[0059] Note: The higher the index above, the lower the rolling resistance and the better the low rolling resistance performance; the greater the wet grip and the better the wet performance; the stronger the anti-stone trapping ability and the better the anti-stone trapping performance. As can be seen from Table 1, when the main groove is designed with only a single element, the tire can only guarantee a single performance. In order to simultaneously guarantee the tire's low rolling resistance, wet performance, and anti-stone trapping performance, the main groove adopts a three-section design (Scheme 5). Further research found that the slit groove 211 adopts a gradual width design to a certain extent (Scheme 10), and the maximum and minimum widths of the slit groove 212 are reasonably designed, which is conducive to further improving the tire's low rolling resistance performance, wet performance, and anti-stone trapping performance, while ensuring the tire's anti-uniform wear performance.

[0060] As shown in the figure, the tire tread has a tread depth H, and the depths of the slits, grooves, and water reservoirs (the distance between grooves along the radial direction of the tire) are denoted as h1, h2, and h3, respectively. The relationship between H and h1, h2, and h3 is as follows: h1 + h2 + h3 = H. A proper distribution of the slit depth h1, groove depth h2, and water reservoir depth h3 is necessary to ensure performance in dry and wet conditions, as well as rolling resistance. To balance dry and wet performance with rolling resistance, the distribution ranges of h1 and h2 are 0.08H ≤ h1 ≤ 0.41H and 0.15H ≤ h2 ≤ 0.55H, respectively. To further improve wet braking and handling performance in the later stages of tire wear, the optimal ranges are 0.15H ≤ h1 ≤ 0.35H, 0.27H ≤ h2 ≤ 0.42H, and 0.25H ≤ h3 ≤ 0.60H.

[0061] With the widths of the slit groove 211, fine groove 212, and water reservoir 213 remaining constant (and the lengths constant), when h2 < 0.15H, h2 is too small, weakening the connection and reinforcement effect of the slit and water reservoir. It also reduces the contact area between the opposite sidewalls during tire rolling, decreasing the self-contact effect of adjacent tread blocks during compression deformation, leading to a weakening of the overall rigidity of the tread blocks and negatively impacting the tire's rolling resistance. When h2 > 0.55H, the slit and water reservoir are too small, reducing the volume of the entire circumferential groove and lowering the tire's wet performance.

[0062] We conducted experimental research on the above design scheme, and the experimental scheme and test results are shown in Table 2. Among them, the rolling resistance index was obtained by testing with an indoor rolling resistance testing machine, and the wet grip index and anti-stone trapping index were obtained by FEA simulation.

[0063] Table 2

[0064]

[0065] Note: The higher the index above, the lower the rolling resistance and the better the low rolling resistance performance; the greater the wet grip and the better the wet performance; the stronger the anti-stone trapping ability and the better the anti-stone trapping performance. Table 2 shows that to ensure the tire's low rolling resistance, wet performance, and anti-stone trapping performance, the depth of the three-section groove's notch 212, fine groove 213, and water reservoir 214 needs to be rationally designed (Scheme 18). Increasing the depth of the middle fine groove 212 to a certain extent is beneficial to improving the tire's low rolling resistance performance (Schemes 19 and 20).

[0066] To enhance the anti-stone trapping performance of tires in the later stages of wear, such as Figure 4As shown, a stone-spraying device 215 is installed in the tire water reservoir 213. The width of the stone-spraying device (the distance of the groove along the tire axial direction) is denoted as W4, where 1mm ≤ W4 ≤ 0.4W3; the depth of the stone-spraying device (the distance of the groove along the tire radial direction) is denoted as h4, where 1mm ≤ h4 ≤ 0.7h3. When the width W4 < 1mm and the depth h4 < 1mm, the stone-spraying device cannot achieve the function of preventing stone trapping in the later stage of tire wear. When the width W4 > 0.4W3 or the depth h4 > 0.7h3, the stone-spraying device significantly reduces the water storage volume of the water reservoir, thereby reducing the tire's wet performance.

[0067] We conducted experimental research on the above design scheme, and the experimental scheme and test results are shown in Table 3. Among them, the rolling resistance index was obtained by testing with an indoor rolling resistance testing machine, while the wet grip index, anti-stone trapping index, and anti-eccentric wear index were obtained by FEA simulation.

[0068] Table 3

[0069]

[0070] Note: ① The higher the above indices, the lower the rolling resistance and the better the low rolling resistance performance; the greater the wet grip and the better the wet grip performance; the stronger the anti-stone trapping ability and the better the anti-stone trapping performance; the stronger the anti-uneven wear ability and the better the anti-uneven wear performance. ② The width of the fine groove in the middle is 1mm and the depth is 5mm. As can be seen from Table 3, a reasonable design of the slit groove 212 cycle is beneficial to improving the tire's rolling resistance, wet grip, and anti-stone trapping performance while ensuring the tire's anti-uneven wear performance. Adding the stone trap 215 at the bottom of the groove is beneficial to improving the tire's anti-stone trapping performance, especially the anti-stone trapping performance in the later stages of tire wear.

[0071] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the scope of the present utility model. Any modifications and improvements made to the technical solution of the present utility model by those skilled in the art without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.

Claims

1. A low rolling resistance pneumatic tire, characterized in that, It has a tread (11), and circumferential grooves (12) are formed on the tread (11); several of the circumferential grooves (12) have a cut groove (211), a fine groove (212) and a water storage groove (213) formed successively from the tread towards the inside of the carcass; The maximum widths of the cut groove (211), the fine groove (212) and the water storage groove (213) along the tire axis are respectively denoted as W1, W2 and W3, and at least satisfy W2 < W1, W2 < W3 and 0.5 mm ≤ W2 ≤ 3 mm.

2. The low rolling resistance pneumatic tire as described in claim 1, characterized in that, The widths of the cut groove (211), the fine groove (212) and the water storage groove (213) satisfy: 4 mm ≤ W1 ≤ 20 mm, and 2.5 mm ≤ W3 ≤ 16 mm.

3. The low rolling resistance pneumatic tire as described in claim 1, characterized in that, The cut groove (211) has a periodically varying opening width along the circumferential direction on the surface of the tread (11), and the periodic pitch L satisfies 0.5PL ≤ L ≤ 4PL.

4. The low rolling resistance pneumatic tire as described in claim 1, characterized in that, The widths of the cut groove (211) at the widest and narrowest points are respectively denoted as W1max and W1min, and the two satisfy 0.3 mm ≤ (W1max - W1min) / 2 ≤ 6 mm.

5. The low rolling resistance pneumatic tire as described in claim 1, characterized in that, The cut groove (211) forms a pair of opposite cut side walls (219), and a non-zero angle α is formed between the opposite cut side walls (219), 20° ≤ α ≤ 120°.

6. The low rolling resistance pneumatic tire as described in claim 1, characterized in that, The water storage groove (213) has opposite water storage wall surfaces (217), and the two opposite water storage wall surfaces (217) form an angle δ towards the inside of the carcass, and the intersection part of the water storage wall surfaces (217) occurs inside the tread, where 30° ≤ δ ≤ 125°.

7. The low rolling resistance pneumatic tire as described in claim 1, characterized in that, The depths of the cut groove (211), the fine groove (212) and the water storage groove (213) are respectively denoted as h1, h2, h3; among them, h1, h2, h3 satisfy: h1 + h2 + h3 = H, 0.08H ≤ h1 ≤ 0.41H, 0.15H ≤ h2 ≤ 0.55H, 0.25H ≤ h3 ≤ 0.60H; where H is the total depth of the circumferential groove (12).

8. The low rolling resistance pneumatic tire as described in claim 1, characterized in that, The bottom of the water storage groove (213) of the water storage groove (213) has a stone ejector (215) protruding from the bottom of the water storage groove (216).

9. The low rolling resistance pneumatic tire as described in claim 8, characterized in that, The width W4 of the stone ejector (215) satisfies 1 mm ≤ W4 ≤ 0.4W3; the depth h4 of the stone ejector (215) satisfies 1 mm ≤ h4 ≤ 0.7h3.

10. The low rolling resistance pneumatic tire as described in claim 1, characterized in that, It also includes a transverse knife groove (13) formed on the tread (11), and the transverse knife groove (13) extends from the circumferential groove (12) towards the tread on both sides of the circumferential groove (12); different transverse knife grooves (13) are staggered or connected on the tread (11); the transverse knife groove (13) can be inclined along the tire circumference.

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