WO2016002089A1

WO2016002089A1 - A tire improved in noise

Info

Publication number: WO2016002089A1
Application number: PCT/JP2014/067994
Authority: WO
Inventors: Takashi Tezuka; Boyong XUE; Salvatore Pagano
Original assignee: Compagnie Generale Des Etablissements Michelin; Michelin Recherche Et Technique S.A.
Priority date: 2014-06-30
Filing date: 2014-06-30
Publication date: 2016-01-07

Abstract

The present invention related to a pneumatic tire having a summit that comprise a tread a plurality of transverse cut-outs circumferentially distributed on at least one axial portion of the tread. The summit further comprises at least a tube extending circumferentially at least along one complete turn. Each tube is filled totally with a liquid polymer. There is at least a filled tube radially inside each axial portion of the tread provided with transversal cut-outs. Each filled tube is located radially the bottom of the transverse cut-out of the transverse cut-outs and a crown reinforcement reinforcing the summit. Each filled tube is made of a material having a Shore A hardness at least equal to 30. The present invention makes it possible to reduce the coast-by noise.

Description

DESCRIPTION

Title of Invention: A TIRE IMPROVED IN NOISE

FIELD OF THE INVENTION

[0001] The present invention relates to pneumatic tires for motor vehicles and to technical solutions for reducing the noise, in particular the outside noise, emitted by said tires during the running of the vehicles.

BACKGROUND

[0002] What is a pneumatic tire: the pneumatic tire comprises a summit prolonged by two sidewalls, the sidewalls being ended by two beads, the summit comprising a tread having a rolling surface intended to come into contact with a ground surface during the running of the pneumatic tire, the pneumatic tire having a carcass reinforcement passing into the summit and the sidewalls and being anchored in the beads, the summit being reinforced by a crown reinforcement placed circumferentially between the carcass reinforcement and the tread, the tread comprising a plurality of cutouts distributed on at least one axial portion of said tread, each cut-out having a bottom distant from the rolling surface by a distance different from zero when the tread is new.

[0003] The problem in general: Limits of tire rolling noise emission in United Nations Economic Commission for Europe Regulation No. l 17 revision 2 implemented in Europe since 2012 are more severe than that in the revision 1 acted from 2005 by about 4 dB (A), and several countries and zones are going to ratify the revision 2. Therefore, there is a compelling need for reducing the tire rolling noise emission (called coast-by noise in the present document) in the worldwide. [0004] Particularly, in order to reduce the coast-by noise, tire manufacturers have provided different solutions related to the composition of the summit of the tires.

[0005] A solution to reduce the coast-by noise is, for example, to arrange a soft rubber compound in and/or under a tread of a summit of a pneumatic tire. Such soft rubber compound may absorb an impact from an unevenness of the ground during the running of the pneumatic tire. That means the tread may reduce "indentation" noise due to the impact. It is generally said that the indentation noise is one of causes of the coast- by noise. However, such solution compound may deteriorate the steering stability because the whole summit of the pneumatic tire has low rigidity.

[0006] As a specific solution, it is known to provide a pneumatic tire with a noise absorber. For an example, the document JP 2001-071723, particularly with figure 4 and example 2 of such document, shows a pneumatic tire having a summit comprising tubes made of aluminum, each tube embedded between a belt and a carcass ply, each tube being oriented by an angle of 45° with the circumferential direction of the pneumatic tire, each tubes being filled with a silicone oil by 50% of the volume of each tubes. Such a tire is totally devoid transverse cut-out.

[0007] However, it is difficult for such tire structure to significantly reduce the coast-by noise. During the running of the pneumatic tire, noise and/or vibration generated by the impact from the ground may travel to the belt through a tread of the summit without absorbed by each filled tube. Such noise and/or vibration may propagate from the belt to other tire parts, for instance sidewalls, and finally the coast- by noise may be generated from the other tire parts. Moreover, aluminum forming the tube has much lower hardness than a rubber composition forming the tread, so that it may be difficult to maintain the initial internal volume of the tube during curing the tire. Additionally, such low hardness may worsen the steering stability of the tire. [0008] Further to get appropriate rolling performances on wet and dry ground a tire and more specifically the tread of such a tire is provided with circumferential and transverse or oblique grooves and/or incisions. Such tread may sufficiently envelop the unevenness of the ground and absorb the impact from the ground during the running of the pneumatic tire, and may increase the indentation noise (edge effect of each transverse cut-out).

[0009] The specific problem solved by the present invention: Now, continuing their researches the applicants have discovered a new solution which can efficiently attenuate the indentation noise originated from a tread provided with transverse cut-outs and maintain the rigidity of a summit of a pneumatic tire, which makes it possible to achieve the above objective, that is to say to reduce the coast-by noise.

DEFINITIONS

[0010] In the present application, the following definitions are to be understood:

[0011] "axial": It is a direction parallel to the axis of rotation of the pneumatic tire; this direction may be "axially interior" when it is oriented towards the inside of the pneumatic tire and "axially exterior" when it is oriented towards the outside of the pneumatic tire.

[0012] "radial": It is a direction that passes through the axis of rotation of the pneumatic tire and normal to the latter; this direction may be "radially internal (or inner)" or "radially external (or outer)" depending on whether it is oriented towards the axis of rotation of the pneumatic tire or towards the outside of the pneumatic tire.

[0013] "bead": It may be an essentially inextensible portion of the pneumatic tire internally radially adjacent to the sidewall and the base of which is intended to be mounted on a rim seat of a vehicle wheel. [0014] "sidewall": It is a portion of the pneumatic tire, usually of low flexural stiffness, prolonging the summit of the pneumatic tire and being ended by two beads, that is, being located between the summit and the bead.

[0015] "crown reinforcement": structure reinforcing the summit of a pneumatic tire and placed circumferentially between the carcass reinforcement and the tread of the pneumatic tire.

[0016] "cut-out": the cut-out means either a groove or an incision or sipe. Incision or sipe is to be distinguished over groove by the fact that in the contact with the road incision is closing at least partially (its opposite walls contact each other).

[0017] "Shore A hardness": The Shore A hardness is assessed in accordance with Standard ASTM D 2240-86.

[0018] "Brookfield Viscosity": It characterizes, in a known way, liquid substances. The apparent viscosity according to the Brookfield method is measured at a given temperature (for example at 45° C) in accordance with European and International Standard EN ISO-2555 (1999) or JIS K7117-1. Use is made, for example, of a BH-type rotary viscometer.

[0019] Moreover, any interval of values denoted by the expression "between a and b" represents the range of values of greater than "a" and of less than "b" (ie the limits a and b excluded) Whereas any interval of values denoted by the expression "from a to b" means the range of values going from "a" to "b" (i.e. including the strict limits a and b).

SUMMARY OF THE INVENTION

[0020] Thus, a first subject matter of the present invention is a pneumatic tire comprising a summit prolonged by two sidewalls, the sidewalls being ended by two beads, the summit comprising a tread having a rolling surface intended to come into contact with a ground surface during the running of the pneumatic tire, the pneumatic tire having a carcass reinforcement passing into the summit and the sidewalls and being anchored in the beads, the summit being reinforced by a crown reinforcement placed circumferentially between the carcass reinforcement and the tread, the tread comprising a plurality of transverse cut-outs circumferentially distributed on at least one axial portion of said tread, each transverse cut-out having a bottom distant from the rolling surface by a distance (di) when the tread is new, the summit further comprising at least a tube extending circumferentially at least along one complete turn (that means at least one roll in a coil or spiral shape), the pneumatic tire being characterized in that: each tube is totally filled with a liquid polymer, radially inside each axial portion (to be defined as the portion limited axially between both axial ends of the crown reinforcement) of the tread provided with transverse cut-outs, there is at least a filled tube, each filled tube is located radially above the crown reinforcement and below the bottom of the transverse cut-outs, each filled tube is made of a material having a Shore A hardness at least equal to 30.

[0021] During the running of the pneumatic tire, the impact from the ground may travel to each filled tube through each axial portion, and the impact may deform each filled tube thanks to such Shore A hardness of the material forming each filled tube. Then the liquid polymer may circulate in each filled tube due to this deformation, and the impact between the road and the tread may be damped without going to the crown reinforcement below each filled tube.

[0022] Therefore, that makes it possible to efficiently absorb the indentation noise generated by the transverse cut-outs with which the tread is provided, and to maintain the rigidity of the summit of the pneumatic tire. [0023] Below the indicated minimum of Shore A hardness, there is a risk of worsening the steering stability and/or decreasing the initial internal volume of each filled tube. The material forming the tube has a Shore A hardness, preferably at least equal to 30 and at most equal to 70. In the range, the deformation of each filled tube may be more sufficient. Also, the tire having each tube totally filled with the liquid polymer may absorb the indentation noise rather than that having each tube partially filled with an air because the impact between the road and the tread may be damped by the former rather than by the latter. Moreover, the former may keep the initial volume of each tube rather than the latter.

[0024] According to a specific aspect of the present invention, each filled tube has a cross section having an axial external width (Li) measured in the axial direction of the pneumatic tire and wherein each axial portion has a transverse width (Wi) and wherein a ratio of the sum (L) of each of axial external widths (Li) of all the filled tubes in each axial portion to the sum (W) of transverse widths (Wi) is at least equal to 30% and at most equal to 90%.

[0025] In the above range of the ratio (called "L/W ratio below) which L is divided by W, each filled tube may more effectively absorb and reduce the impact which the axial portion receives from the ground.

[0026] Preferably, the LAV ratio is at least equal to 35% and at most equal to 60%.

[0027] According to a specific aspect of the present invention, the Brookfield viscosity of the liquid polymer is at least equal to 0.1 to at most equal tolOO Pa.s at least equal to 40 °C and at most equal to 60 °C.

[0028] Such viscosity in the above range may function as friction that indirectly may resist the impact generated by the impact from the ground to attenuate the impact. [0029] According to a specific aspect of the present invention, the distance di is at least equal to 1 mm and at most equal to 5 mm.

[0030] The above range may make sufficient spaces to locate each filled tube between the bottom of transverse cut-outs and the crown reinforcement.

[0031] According to a specific aspect of the present invention, each filled tube has a cross section having an axial external width (Li) and an axial internal width (Mi) measured in the axial direction of the pneumatic tire and wherein difference between Li and Mi is at least equal to 0.5 mm and at most equal to 2.5 mm.

[0032] In the above range, the impact from the ground may efficiently deform each filled tube in order to absorb the impact from the ground, and the form of each tube may maintain the internal volume of each filled tube.

[0033] According to a specific aspect of the present invention, each filled tube has an internal volume (Ti) and wherein each axial portion of the tread provided with the transverse cut-outs has a volume (Pi) and wherein the T/P ratio of the sum (T) of Ti in the sum (P) of Pi is at least equal to 10% and at most equal to 90%.

[0034] In the above range of the T/P ratio, each filled tube may more effectively prevent the impact, which the axial portion receives from the ground, from travel to the crown reinforcement.

[0035] Preferably, the T/P ratio is at least equal to 20% and at most equal to 80%, more preferably at least equal to 20% and at most equal to 50%.

[0036] According to a specific aspect of the present invention, the tread comprises at least a circumferential cut-out extending, wherein, between the circumferential cutout and either of the sidewalls, the axial portion(s) of the tread provided with the transverse cut-outs is located and the filled tube(s) is evenly spaced in the axial direction. [0037] According to a specific aspect of the present invention, the tread comprises at least two circumferential cut-out extending, wherein, between the two adjacent circumferential cut-outs, the axial portion(s) of the tread provided with the transverse cut-outs is located and the filled tube(s) is evenly spaced in the axial direction.

[0038] Such location may maintain even rigidity of the tread to keep the stability of the pneumatic tire.

[0039] According to a specific aspect of the present invention, at least one tube filled with the liquid polymer is additionally arranged between the crown reinforcement and other axial portion(s) of the tread without transverse cut-out.

[0040] Such arrangement may help to additionally absorb the impact generated by the ground on the tread.

[0041] According to a specific aspect of the present invention, wherein the liquid polymer is chosen from the group consisting of liquid polybutadienes, liquid polyisoprenes, liquid copolymers of butadiene and styrene and mixtures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Other characteristics and advantages of the invention arise from the description made hereafter in reference to the annexed drawings which show, as nonrestrictive examples, of the embodiments of the object of the invention.

[0043] In these drawings:

FIG. 1 shows a schematic view of a tire cross sectional view of a first embodiment of the invention.

[0044] FIG. 2 shows a plan view of a tread part of the first embodiment of the invention;

[0045] FIG. 3 shows a schematic view of axial portions of a tread having transverse cut-outs of the first embodiment of the invention.

[0046] FIG. 4 shows a schematic view of a tire cross sectional view of a second embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0047] The appended FIG. 1 schematically (in particular not to a specific scale) represents, in radial cross section, a pneumatic tire (1) of dimension 205/55R16, width of a tread 164 mm, and thickness of the center of the tread 8.4 mm according to one embodiment of the present invention.

[0048] In the FIG. 1, the pneumatic tire (1) comprises a summit (2) prolonged by two sidewalls (5), the sidewalls (5) being ended by two beads (4), a carcass reinforcement (6) passing into the summit (2) and the sidewalls (5) and being anchored in the beads (4).

[0049] The summit (2) comprises a tread (3) having rolling surfaces intended to come into contact with a ground surface during the running of the pneumatic tire (1).

[0050] The summit (2) is, in a manner known per se, reinforced by a crown reinforcement (7) which is at least partly metallic and radially external with respect to the carcass reinforcement (6) passing into the summit (2), the crown reinforcement (7) being formed from two superposed crossed plies reinforced by metal cords. The crown reinforcement (7) is placed circumferentially between the carcass reinforcement (6) and the tread (3).

[0051] The carcass reinforcement (6) is here anchored into each bead (4) by winding around two bead wires (4a, 4b), the turn-up (6a, 6b) of the reinforcement (6) being for example positioned towards the outside of the pneumatic tire (1), which is shown here mounted on its rim (9). [0052] FIG. 1 illustrates that there are six tubes filled totally with B- 1000 (liquid 1 ,2-polybutadiene) provided by Nippon Soda Co., Ltd. as a liquid polymer, each filled tube extending circumferentially along one a complete turn in the summit (2) and wherein four of the tubes (1 1) are radially embedded inside two axial portions (3b, 3c) of the tread (3), the two axial portions (3b, 3c) provided with transverse cut-outs (10a, 10b) having a bottom distant from the rolling surface by a distance

2mm), the four of the tubes (1 1) are located above the crown reinforcement (7) and below the bottom of the transverse cut-outs (10a, 10b) and have a cross section having an axial external width (Li, L₂, L₃, L₄: 4.6mm) and an axial internal width (Mi, M₂, M₃, M4: 3.0mm).

[0053] In FIG. 1 , each filled tube is made of cured natural rubber (without filler) provided by Fuso rubber industry Co., Ltd. The cured natural rubber has Shore A hardness equal to 35.

[0054] The material forming each filled tube may be metal, polymer as for example plastic and/or rubber composition. It is preferably made of at least an elastomer, the elastomer being more preferably chosen from the group consisting of diene elastomers, thermoplastic elastomers and mixture thereof; still more preferably; each filled tube is made of a rubber composition comprising at least an elastomer and an additive.

[0055] Preferably, each filled tube is made of a diene elastomer rubber composition, with or without any reinforcing filler.

[0056] Preferably, each filled tube is made of at least a thermoplastic elastomer having a softening point which is higher than the usual curing temperatures used for the pneumatic tires.

[0057] Preferably, the liquid polymers resulting from the polymerization of dienes, such as, for example, those selected from the group consisting of polybutadienes (BR), polyisoprenes (IR), copolymers of butadiene and styrene (SBR), and the mixtures of the liquid diene polymers, are also suitable. The liquid polymer is still more preferably liquid BR. Such liquid polymers are well known and are commercially available, for example known as "B-1000" and "B-2000" (Liquid 1 ,2-Polybutadiene) provided by Nippon Soda Co., Ltd.

[0058] The tubes may be filled with the liquid polymer by any equipment for inserting the liquid, for instance an injection system, and then one end of each tube may be jointed with the other end of said tube so that the liquid is hermetically closed inside the tube by the material forming the tube. ^~

[0059] In FIG. 1, the width (Wl, W2) of each axial portion (3b, 3c) is 25 mm.

[0060] In FIG. 1, a distance (d₂) from the radially outermost part of the four filled tubes (11) to the bottom of the transverse cut-outs (10a, 10b) is 0.9 mm.

[0061] In FIG. 1, the tread (3) comprises three circumferential cut-outs (8a, 8b, 8c) extending, each circumferential (8a, 8b, 8c) cut-out having a bottom distant from the rolling surface by 5 mm and wherein between the two adjacent circumferential cut-outs (8a and 8b, 8b and 8c), the axial portions (3b, 3c) of the tread (3) provided with the transverse cut-outs (10a, 10b) are located and each of the four filled tubes (11) is evenly spaced in the axial direction.

[0062] In the FIG. 1, the width (CW) of each circumferential cut-out (8a, 8b, 8c) is 5 mm.

[0063] In FIG. 1, other two tubes, which have a cross section having an axial external width (4.6mm) and an axial internal width (3.0mm) and are totally filled with B-1000, are additionally arranged between the crown reinforcement (7) and two axial parts (3a, 3d) of the tread (3) without transverse cut-out. A distance from the radially outermost part of each of the two tubes to the rolling surface is equal to the sum of dl and d2. [0064] The appended FIG. 2 schematically (in particular not to a specific scale) represent, in plan, the tread of the summit of the pneumatic tire corresponding to the first embodiment shown with FIG. 1.

[0065] The tread shown schematically comprises the axial portions (3b, 3c) having widths (Wl, W2) delimited by the circumferential cut-outs (8a, 8b, 8c), a plurality of the transverses cut-outs (10a, 10b) circumferentially distributed on each of the axial portions (3b, 3c), and such transverse cut-outs (10a, 10b) being oriented with an angle relative to the circumferential direction equal to 90°. The arrow C indicates a rolling direction of the pneumatic tire (1).

[0066] In the FIG. 2, the width (TW) of each transverse cut-out ( 10a, 10b) is 5 mm.

[0067] The transverse cut-outs may be located axially between both axial ends of the crown reinforcement.

[0068] The transverse cut-outs may be oriented with the angle that deviates by more than 5° from the circumferential direction.

[0069] FIG. 3 illustrates a cutaway of the tread (3) shown with FIG.1 and FIG.2. In FIG. 3, P indicates a volume of the axial portion (3b) with transverse cut-outs (10a).

[0070] In FIG. 4, each filled tube (11) has different distance to the rolling surface (and the bottom of the transverse cut-outs (10a, 10b)) with others. That arrangement may make transverse rigidity of the summit of the pneumatic tire equivalent in parallel to maintain noise/ vibration absorbability of the filled tubes.

RUNNING TESTS

[0071] The goal of these tests is to compare an anti-coast-by noise performance of three pneumatic tires according (denoted T-2, T-3 and T-4) to the present invention with a reference tire (denoted T-l) devoid of tubes. [0072] All the pneumatic tires have a tread corresponding to the first embodiment shown in FIG. 2. T-2 and T-4 have a tire cross section shown in FIG. l, and T-3 has same tire section as T-2 and T-4 apart from number of the tubes. In T-3, six of the tubes are radially embedded inside axial portions of the tread provided with transverse cutouts. Table 1 shows values obtained from tire structures for each tire.

Table 1

(1) A material of the tubes: Cured natural rubber without any reinforcing filler (Fuso rubber industry Co., Ltd, Shore A: 35)

(2) B-1000: Liquid 1 ,2-Polybutadiene (Nippon Soda Co., Ltd), Brookfield Viscosity (45°C) measured by a BH-type rotary viscometer in accordance with ISO-2555: 1.0 Pa · s

[0073] - T-l : A control pneumatic tire without tube;

- T-2: A pneumatic tire according to the invention (d2=0.9mm, number of tubes under axial portions with transverse cut-outs: 4);

- T-3: A pneumatic tire according to the invention (d2=0.8mm, number of tubes under axial portions with transverse cut-outs: 6);

- T-4: A pneumatic tire according to the invention (d2=0.2mm, number of tubes under axial portions with transverse cut-outs: 4).

[0074] Process: One end of each filled tube was jointed with the other end of the tube in order to be hermetically closed. The above pneumatic tires were conventionally manufactured with a size of 205/55 R16 and in all respects identical apart from the tubes.

[0075] Evaluation test: In order to compare the anti-coast-by noise performance between each invention tire (T-2, T-3 and T-4) and the reference one (T-l), machine rolling tests were performed by placing in contact (each tire under 180 kPa of inflation pressure of the pneumatic tire mounted on 6.5Jxl6 rim and subjected to 4.25 kN of load of the pneumatic tire) on the outer surface of a cylinder provided with a rough surface. The assembly is placed in a soundproof chamber (semi-anechoic). Several microphones are placed around the contact area to record the coast-by noise level during rolling, over a range of frequencies ranging from 500 to 2500 Hz, for a given rolling speed (80 km/hour).

[0076] The result from Table 2 expresses the differences in the recorded sound level between each of the pneumatic tires (T-2, T-3 and T-4) in accordance with the present invention and the control pneumatic tire (T-l), at a frequency range from 500 to 2500 Hz.

[0077] These differences are expressed as sound energy (dB(A)) which corresponds to the integration of the sound pressure as a function of the frequency at the frequency range in question, a negative value indicating a reduction in the noise relative to the control pneumatic tire (T-l).

[0078] On reading Table 2, it is unexpectedly observed that, at the effective frequency range (500 to 2500Hz) typical of coast-by noise, the pneumatic tires (T-2, T- 3 and T-4) of the present invention emit much less noise than the control pneumatic tire (T-l), a reduction of from 0.8 to 2.9 dB(A) for example being considered significant for a person skilled in the art.

Table 2

(3) Difference between each of the invention tires and the reference tire

[0079] The invention is not limited to the examples described and represented and various modifications, for instance each tube has a cross section having a form chosen from the group consisting of circle, oval, triangle and quadrilateral, can be made there without leaving its framework as fixed by the following claims.

Claims

1. A pneumatic tire comprising a summit prolonged by two sidewalls, the sidewalls being ended by two beads, the summit comprising a tread having a rolling surface intended to come into contact with a ground surface during running of the pneumatic tire, the pneumatic tire having a carcass reinforcement passing into the summit and the sidewalls and being anchored in the beads, the summit being reinforced by a crown reinforcement placed circumferentially between the carcass reinforcement and the tread, the tread comprising a plurality of transverse cut-outs circumferentially distributed on at least one axial portion of said tread, each transverse cut-out having a bottom distant from the rolling surface by a distance (di) when the tread is new,

the summit further comprising at least a tube extending circumferentially at least along one complete turn, the pneumatic tire, being characterized in that:

- each tube is totally filled with a liquid polymer;

- radially inside each axial portion of the tread provided with transverse cut-outs, there is at least a filled tube;

- each filled tube is located radially above the crown reinforcement and below the bottom of the transverse cut-outs;

- each filled tube is made of a material having a Shore A hardness at least equal to

30.

2. The pneumatic tire according to Claim 1, wherein each filled tube has a cross section having an axial external width (Li) measured in the axial direction of the pneumatic tire and wherein each axial portion has a transverse width (Wi) and wherein the L/W ratio of the sum (L) of each of axial external widths (Li) of all the filled tubes in each axial portion to the sum (W) of transverse widths (Wi) is at least equal to 30% and at most equal to 90%.

3. The pneumatic tire according to Claim 1 or Claim 2, wherein the Brookfield viscosity of the liquid polymer is at least equal to 0.1 to at most equal to 100 Pa.s at least equal to 40°C to at most equal to 60 °C.

4. The pneumatic tire according to any one of Claims 1 to 3, wherein the distance d_\ is at least equal to 1 mm and at most equal to 5 mm.

5. The pneumatic tire according to any one of Claims 1 to 4, wherein each filled tube has a cross section having an axial external width (Li) and an axial internal width (Mi) measured in the axial direction of the pneumatic tire and wherein difference between Li and Mi is at least 0.5 mm and at most 2.5mm.

6. The pneumatic tire according to any one of Claims 1 to 5, wherein each filled tube has an internal volume (Ti) and wherein each axial portion of the tread provided with the transverse cut-outs has a volume (Pi) and wherein the T/P ratio of the sum (T) of Ti in the sum (P) of Pi is at least equal to 10% and at most equal to 90%.

7. The pneumatic tire according to any one of Claims 1 to 6, wherein the tread comprises at least a circumferential cut-outs extending, and wherein, between the circumferential cut-out and either of the sidewalls, the axial portion(s) of the tread provided with the transverse cut-outs is located and the filled tube(s) is evenly spaced in the axial direction.

8. The pneumatic tire according to any one of Claims 1 to 7, wherein the tread comprises at least two circumferential cut-outs extending, and wherein, between the two adjacent circumferential cut-outs, the axial portion(s) of the tread provided with the transverse cut-outs is located and the filled tube(s) is evenly spaced in the axial direction.

9. The pneumatic tire according to any one of Claims 1 to 8, wherein at least one tube totally filled with the liquid polymer is additionally arranged between the crown reinforcement and other axial portion(s) of the tread without transverse cut-out.

10. The pneumatic tire according to any one of Claims 1 to 9, wherein the liquid polymer is chosen from the group consisting of liquid polybutadienes, liquid polyisoprenes, liquid copolymers of butadiene and styrene and mixtures thereof.