Commercial vehicle tyre, use thereof and three-axle semi-trailer

Abstract

The invention relates to a commercial vehicle tyre comprising a tread (1) with shoulder flanks (4) and a plurality of circumferential grooves (3) extending in the circumferential direction, which grooves divide the tread (1) into circumferential ribs (2) and of which at least one is formed in the provided profile depth (T), with this at least one groove being the deepest circumferential groove of all the circumferential grooves (3), wherein the tread (1) has a tread gross volume (VB) which is located between the tread periphery extending in the circumferential direction and a surface (F1) that extends in the tread (1) in parallel with the tread periphery, touches the deepest circumferential groove (3) radially from the inside, extends in the circumferential direction, and extends laterally as far as the shoulder flanks (4), and wherein all the profile negatives formed within the tread gross volume (VB), such as the circumferential grooves (3) and other grooves and recesses, overall have a groove empty volume (VR) which is 1% to 9% of the tread gross volume (VB). The commercial vehicle tyre has a profile depth (T) of 4.00-9.00 mm in the tread.

Description

[0001] 202404114

[0002] Description

[0003] Commercial vehicle tires, their use and three-axle semi-trailer

[0004] The invention relates to a commercial vehicle tire with a tread having shoulder flanks and with several circumferential grooves which divide the tread into circumferential ribs and of which at least one is designed to the intended profile depth and which is the deepest circumferential groove of all the circumferential grooves, wherein the tread has a gross tread volume which is located between the circumferentially running tread periphery and a circumferentially running surface extending laterally to the shoulder flanks, parallel to the tread periphery in the tread, and wherein all profile negatives formed within the gross tread volume, such as the circumferential grooves and other grooves and cuts, have a total groove empty volume which amounts to 1% to 9% of the gross tread volume.

[0005] The invention further relates to a use of the commercial vehicle tires and a three-axle semi-trailer, which is offered as a new vehicle or goes on sale.

[0006] A commercial vehicle tire of the type mentioned above is known from EP 2 292 448 A1. The tread has circumferential grooves with a tread depth of 10.00 mm to 25.00 mm. The groove empty volume of only 1% to 9% of the gross tread volume results in such an increase in tread stiffness in the radial direction that the deformation amplitude of the tread is reduced to an extent that overcompensates for the expected effect – increased rolling resistance due to more rubber. The rolling resistance of the tire is thus reduced, and the achievable reduction in rolling resistance can be significant, depending on the proportion of the groove volume. 202404114

[0007] These commercial vehicle tires are specifically designed for use as truck, bus and trailer tires, preferably for use on the trailer or trailing axle of such vehicles, and have the usual construction of radial pneumatic tires for these applications.

[0008] Reducing the rolling resistance of commercial vehicle tires remains a dominant topic. Tire rolling resistance is typically determined using rolling resistance drum tests according to ISO 28580 (edition 2018 / 07). The test results are used, for example, to calculate and / or reduce a vehicle's tire-related fuel consumption and / or emissions, as tire rolling resistance makes a significant contribution to these figures.

[0009] Fuel consumption calculations for commercial vehicles or semi-trailers are also carried out, for example, according to the VECTO Tool (Vehicle Energy Consumption Calculation Tool), which was developed on behalf of the European Commission.

[0010] It is common practice for semi-trailers, which are launched or offered for sale by trailer manufacturers as new vehicles, to be fitted with identical tires, i.e., the same type of commercial vehicle tire, on all three free-rolling axles. Commercial vehicle tires for semi-trailers are known to have a groove void volume in the tread that is between 7% and 16% of the gross tread volume. However, for commercial vehicle tires for trailers intended for use on unpaved roads, the groove void volume can be higher than 16%.

[0011] It is known that semi-trailers, especially their tires mounted on the free-rolling axles, contribute significantly to the vehicle's energy consumption and emissions, particularly heavily loaded tires. 202404114

[0012] The use of low rolling resistance commercial vehicle tires on semi-trailers has so far been limited due to the expectation of lower wear performance, and thus a reduced tire lifespan. The effect of low rolling resistance commercial vehicle tires on semi-trailers is difficult for customers to quantify, which is why such tires are not preferred, even though they offer significantly improved rolling resistance and only a slightly reduced lifespan compared to standard tires. While the lifespan of low rolling resistance commercial vehicle tires on semi-trailers can be reliably determined from experience, the effects on fuel consumption and emissions are either impossible or very imprecise to quantify.

[0013] Observations and subsequent analyses have shown that commercial vehicle tires on individual free-rolling axles are subjected to very different stresses, which is reflected in the service life of the tires when comparing them on the individual axles. Observations and analyses by the applicant have shown that if the service life of the tires on the front axle is assessed at 100%, the service life of the tires on the second, middle axle is approximately 180%, and the service life of the tires on the third, rear axle is approximately 95%. These figures are exemplary and refer to a 40-ton truck with a box-type semi-trailer. These different service lives are due to the different lateral forces acting on the tires on the individual axles, particularly when cornering.In particular, the lateral forces acting on the commercial vehicle tires on the middle axle are significantly lower compared to those acting on the commercial vehicle tires on the front and rear axles.

[0014] Different load conditions of the semi-trailer typically have no significant impact on the relative service life of the tires on the individual axles, as the radial load, i.e., the mass of the semi-trailer, is distributed relatively evenly across the axles. Due to the longer service life of the tires on the middle axle, these tires tend to experience uneven wear or age-related cracking on the outer tread surface. To prevent or counteract such phenomena, it is common practice to remount tires located on the middle axle to the front or rear axle during their service life.In practice, this involves the effort of remounting the tires, the associated downtime of the semi-trailer, and the necessary regular checks of the commercial vehicle tires on the middle axle in order to carry out a timely remounting of the commercial vehicle tires.

[0015] The invention is based on the objective of further improving or optimizing a commercial vehicle tire of the type mentioned above with regard to rolling resistance.

[0016] The invention is further based on the objective of reducing the tire-related fuel consumption or tire-related emissions of a vehicle by using the commercial vehicle tires according to the invention.

[0017] Another object of the invention is to equip a three-axle semi-trailer, which is offered as a new vehicle and / or goes on sale, with commercial vehicle tires according to the invention in such a way that the tire-related fuel consumption or the tire-related emissions of the semi-trailer are reduced.

[0018] The first problem described above, relating to the commercial vehicle tire, is solved according to the invention by the fact that the commercial vehicle tire has a tread depth of 4.00 mm to 9.00 mm.

[0019] Commercial vehicle tires according to the invention are therefore, with regard to their

[0020] Rolling resistance is further reduced compared to that of prior art 202404114 and can even exhibit a rolling resistance of < 3.5 kg / t according to ISO 28580:2018. Observations have shown that the rolling resistance advantage of commercial vehicle tires according to the invention is 70 g / t to 130 g / t per mm of reduced tread depth compared to prior art commercial vehicle tires. The rolling resistance of commercial vehicle tires according to the invention is therefore further reduced in addition to the optimization of rolling resistance through the small groove void volume.

[0021] Commercial vehicle tires according to the invention are furthermore preferably type-approved as FRT (Free Rolling Tyre) in accordance with UN / ECE Regulation No. 54 and marked as such. Regulation No. 54 of the United Nations Economic Commission for Europe (UN / ECE, published on July 11, 2008, in the Official Journal of the European Union) ensures that approved tires meet certain requirements regarding their dimensions and markings, and that they have passed a load-speed endurance test in accordance with this regulation. Commercial vehicle tires according to the invention advantageously meet these quality criteria.

[0022] Preferably, a commercial vehicle tire according to the invention is a heavy-duty tire with a load index > 156. With a heavy-duty tire of such a load index, the rolling resistance is higher than with a less durable tire with a lower load index. The reduced rolling resistance achievable with commercial vehicle tires according to the invention is therefore particularly noticeable with tires having a load index > 156.

[0023] Since the rolling resistance advantage of commercial vehicle tires according to the invention is 70 g / t to 130 g / t per mm of reduced tread depth, as mentioned above, it is particularly advantageous if the tread depth in the running surface is at most 8.00 mm, more preferably at most 7.00 mm, more preferably at most 6.00 mm, and more preferably at most 5.00 mm. 202404114

[0024] The groove empty volume also influences the rolling resistance, whereby according to preferred embodiments the groove empty volume is at most 8%, in particular at most 7% and particularly preferably at most 6%, in particular at most 5%.

[0025] There are a number of particularly advantageous combinations of tread depth with the groove empty volume VR in the tread.

[0026] In one of these advantageous and preferred combinations, the profile depth is at most 9.00 mm and the groove empty volume is at most 7% or at most 8%.

[0027] In a further preferred embodiment, the tread depth is at most 9.00 mm and the groove empty volume VR is at most 5% or at most 6%. In a further preferred variant, the tread depth is at most 8.00 mm and the groove empty volume VR is at most 6% or 7%; according to a still further variant, the tread depth is at most 8.00 mm and the groove empty volume VR is at most 5%.

[0028] The second problem described above, relating to the use of the invention, is solved by using commercial vehicle tires according to the invention on a semi-trailer having three free-rolling axles, offered or offered for sale as a new vehicle, wherein the commercial vehicle tires are mounted exclusively on the middle axle of the three free-rolling axles, or on a tractor unit having a free-rolling trailing axle, such as a semi-trailer tractor, or a bus having a free-rolling trailing axle, in each case exclusively on the free-rolling trailing axle.

[0029] The third problem described above is solved by a three-axle semi-trailer, which is offered and / or sold as a new vehicle, and which has three free-rolling axles, a front axle, a middle axle, and a rear axle. 202404114

[0030] axle and a rear axle, wherein commercial vehicle tires are mounted on each of these three axles, wherein commercial vehicle tires according to the invention are mounted on the middle axle, and wherein commercial vehicle tires are mounted on the front and rear axles, which have a tread depth in the running surface that is at least 1.00 mm greater than the tread depth of the commercial vehicle tires mounted on the middle axle.

[0031] According to the invention, commercial vehicle tires according to the invention are mounted on the middle free-rolling axle of three-axle semi-trailers, before they are sold new, or on free-rolling trailing axles of tractors or buses, also before they are sold new. It is particularly advantageous that semi-trailers according to the invention have commercial vehicle tires according to the invention mounted on the middle free-rolling axle when ready for sale. Other FRTs, such as tires from a different manufacturer or with a different trade name, can be mounted on the two other free-rolling axles, with these tires having a greater tread depth when new than the tire according to the invention mounted on the middle axle.This allows the service life of the commercial vehicle tires mounted on the free-rolling axle of semi-trailers to be matched to that of the commercial vehicle tires on the other axles, thus eliminating the aforementioned remounting and the phenomena expected during remounting, such as uneven wear or age-related cracking on the outer tread surface, as seen with conventional tires. Since the commercial vehicle tires according to the invention are further improved and optimized with regard to rolling resistance, rolling resistance advantages also result for the semi-trailer, tractor unit, or bus itself.Depending on the combination of commercial vehicle tires according to the invention with other commercial vehicle tires, in particular those according to the prior art, a noticeable rolling resistance advantage results not only in semi-trailers, but also in tractors or buses, if the latter are fitted with commercial vehicle tires according to the invention on their freely rolling trailing axles.

[0032] In a preferred embodiment of the three-axle semi-trailer offered or sold as a new vehicle, commercial vehicle tires are mounted on the front and rear axles. These tires have a tread depth that is at least 1.50 mm, preferably at least 2.00 mm, and particularly up to 6.00 mm, greater than the tread depth of the commercial vehicle tires on the middle axle. For example, the front and rear trailer axles may be fitted with commercial vehicle tires from the same tire manufacturer under a different trade name, or with tires from a manufacturer other than the manufacturer of the tires on the middle axle.To ensure the advantages of the commercial vehicle tires according to the invention on the middle trailer axle, it is important to coordinate the relative mileage per mm of tread depth of the individual tires on the three trailer axles so that the rolling resistance advantage for the three-axle semi-trailer reaches a noticeable value.

[0033] Further features, advantages, and details of the invention will now be described in more detail with reference to the drawing, which schematically illustrates exemplary embodiments. The drawing shows

[0034] Fig. 1 shows a circumferential section of a tread of a vehicle tire for commercial vehicles with a variant of a tread profile.

[0035] Fig. 2 shows a side view of a three-axle semi-trailer coupled to a tractor unit (a truck).

[0036] Fig. 3 shows a side view of a three-axle semi-trailer coupled to a tractor unit (a truck) with a single trailing axle. 202404114

[0037] Commercial vehicle tires according to the invention have, in particular, a load index > 156 and are so-called free-rolling tires (FRT). The designation FRT is a marking according to UN / ECE Regulation No. 54, which indicates that the commercial vehicle tire is specifically intended for trailer axles and unsteered or non-driven axles of commercial vehicles. In addition to their use on trailers, commercial vehicle tires according to the invention are also suitable for use on unsteered and non-driven trailing axles of semi-trailers or buses. Trailing axles serve to reduce weight and are located downstream of the respective drive axle of the vehicle.

[0038] Fig. 1 shows an exemplary and schematic embodiment of a tread 1 of a commercial vehicle tire with six circumferential ribs 2, separated from one another by five circumferential grooves 3, which are identical in the embodiment shown. The circumferential grooves 3 have straight and parallel edge edges 4 at the periphery of the tread, the distance between which corresponds to the width of the circumferential groove 3 in a new tire and is, for example, 5.00 mm to 15.00 mm. In other embodiments not shown, the tread has, for example, three circumferential grooves 3 in combination with two narrower circumferential grooves, which have a width of, for example, 1.00 mm to 5.00 mm at the periphery of the tread. The tread 1 has shoulder flanks 4 on the shoulder side.

[0039] The circumferential grooves 3 and other circumferential grooves can run circumferentially in any zigzag or wave pattern and have groove flanks that are provided with a structure, for example, from surface elements forming projections and depressions. At least one of the circumferential ribs 2 can be divided into blocks or structured in a block-like manner by transverse grooves, incisions, and the like, as not shown. 202404114

[0040] The circumferential grooves 3 can have one of the cross-sections known from the prior art, in particular a conventional U-shaped or V-shaped cross-section, or cross-sectional shapes with radial sections of different widths and / or geometric shapes.

[0041] At least one circumferential groove 3, and in particular several of the circumferential grooves 3 formed in the tread, have the maximum depth specified for the respective tire type, the tread depth T. The tread depth T is the radially measured distance between the deepest points of the circumferential groove(s) 3 and the tread periphery of a new tire. For commercial vehicle tires according to the invention, the tread depth T is at least 4.00 mm and at most 9.00 mm, preferably at most 8.00 mm, particularly preferably at most 7.00 mm, and most preferably at most 6.00 mm, and in particular at most 5.00 mm. No other tread features, such as other circumferential grooves, no other groove, and none of the possibly provided cuts have a greater depth than the tread depth T.

[0042] In Fig. 1, a line Li is drawn on the front cut surface of the cross-section along the deepest points of the circumferential grooves 3, which are executed at tread depth T. This line runs parallel to the tread periphery and extends tangentially towards the outer edges of the shoulder flanks 4, continuing its parallel course to the tread periphery. Line Li represents a surface Fi circumferentially within the tire, parallel to the tread periphery. Between surface Fi and the circumferential surface at the tread periphery, the tread 1 has a gross tread volume VB. The gross tread volume VB is composed of the rubber volume VG of the tread and the total groove volume VR between the aforementioned surfaces. The groove volume VR is therefore the sum of all volumes of the circumferential grooves, transverse grooves, cuts, and the like within the gross volume VB.The rubber volume (VG) and groove volume (VR) refer to a commercial vehicle tire that is not mounted on a rim and has no tire pressure. 202404114.

[0043] In commercial vehicle tires according to the invention, the proportion of the groove volume VR to the gross volume VB is at least 1% and at most 9%, preferably at most 8%, in particular at most 7% and especially preferably at most 6%, in particular at most 5%.

[0044] The groove volume VR can be determined, for example, by a three-dimensional X-ray examination, a computed tomography scan, of the tread 1. Within the gross tread volume VB, the density differences between the rubber compound of the tread 1 and the air in the grooves (the groove volume VR) are determined by computed tomography, thus determining the rubber volume VG and the groove volume VR. The ratio of the groove volume VR ZUI I to the tread gross volume VB ultimately yields the percentage of the groove volume VR. The measurement is performed on commercial vehicle tires that are not mounted on a rim and have no tire pressure.

[0045] Fig. 2 shows a schematic side view of a tractor unit 5 with a semi-trailer 6 having three freely rolling, tire-equipped axles 7, 8 and 9: a front axle 7, a middle axle 8 and a rear axle 9. The tractor unit 5 has a tire-equipped steering axle 10 and a tire-equipped drive axle 11. Commercial vehicle tires, for example with a load index > 156, are mounted on axles 7, 8 and 9.

[0046] On the middle axle 8, commercial vehicle tires are mounted, the tread depth T of which, as explained and defined in detail above, is at least 4.00 mm and at most 9.00 mm, and in whose tread the proportion of the groove volume VR to the gross volume VB is at least 1% and at most 9%, also as explained and defined in detail above. On the front and rear axles 7, 9, in particular other commercial vehicle tires of type FRT, for example, those of other manufacturers or those with a different trade name than the tires according to the invention, are mounted. These commercial vehicle tires have a tread depth that is at least 1.00 mm, in particular at least 1.50 mm, preferably at least 2.00 mm and up to 6.00 mm, greater than the tread depth T of the commercial vehicle tires on the middle axle 8.

[0047] The commercial vehicle tires on axles 7, 8, and 9 are ideally matched to each other so that they exhibit comparable lifespans and largely consistent tread wear patterns over their service life or maximum operating time. Tread wear patterns primarily refer to phenomena such as uneven wear and age-related cracking.

[0048] The commercial vehicle tires on the middle axle 8 exhibit lower rolling resistance compared to the commercial vehicle tires on the front and rear trailer axles 7, 9. For each percent reduction in groove volume VR, the rolling resistance advantage is typically 40 g / t to 100 g / t, and for each millimeter of reduced tread depth T, it is typically around 70 g / t to 130 g / t.

[0049] Fig. 3 shows a side view of a tractor unit with a steering axle 12, a drive axle 13, and a trailing, freely rolling trailing axle 14. A semi-trailer with three freely rolling trailer axles 7, 8, and 9, fitted with commercial vehicle tires as described above, is mounted on the tractor unit. Commercial vehicle tires according to the invention are mounted on the freely rolling trailing axle 14, while conventional drive axle tires with a tread depth of at least 8.00 mm and a groove volume of at least 9% of the gross tread volume, as defined above, are mounted on the drive axle 13.

[0050] Tables 1, 2, and 3 below each show two examples of tire configurations for the three trailer axles of a semi-trailer. The upper example in each table (referred to as "NFZ (SDT)") is an example with three identical commercial vehicle tires according to the prior art on all three trailer axles of the semi-trailer. The lower example in each table (referred to as "NFZ (Invention middle trailer axle)") is an example according to 202404114

[0051] The invention describes a commercial vehicle tire on the middle trailer axle and, according to the prior art, a commercial vehicle tire on the front and rear trailer axles of the semi-trailer. The specifications and data for the commercial vehicle tires designed according to the invention are highlighted in bold for easier differentiation from the specifications and data for the commercial vehicle tires according to the prior art.

[0052] Additional explanations regarding the tables:

[0053] Typical groove void volume of commercial vehicle tires according to the state of the art for axles of a semi-trailer: 7% to 16%, in individual cases even more.

[0054] Typical tread depth of commercial vehicle tires according to the state of the art for the axles of a semi-trailer: usually 9.00 mm to 14.00 mm.

[0055] The rolling resistance advantage of commercial vehicle tires according to the invention per mm of reduced tread depth compared to prior art commercial vehicle tires is 70 g / t to 130 g / t (based on empirical values). The calculations in the tables were based on 70 g / t to demonstrate a minimum advantage that can be expected based on empirical data.

[0056] The rolling resistance advantage of commercial vehicle tires according to the invention per % reduction in groove volume compared to prior art commercial vehicle tires is typically 40 g / t to 100 g / t (based on experience). The calculations in the tables were based on 40 g / t to demonstrate a minimum expected advantage in the rolling resistance calculation.

[0057] Example 1 assumes that the tires are already optimized for low rolling resistance in accordance with the state of the art, as evidenced by the shallow tread depth of 10.00 mm and the low groove void volume of 7%. 202404114

[0058] Example 2 assumes average rolling resistance-optimized commercial vehicle tires according to the state of the art, as evidenced by the tread depth of 11.50 mm and the groove empty volume of 12%. Example 3 assumes non-rolling resistance-optimized commercial vehicle tires according to the state of the art, as evidenced by the tread depth of 14.00 mm and the groove empty volume of 16%.

[0059] In Example 1 (Table 1), the rolling resistance advantage of the commercial vehicle tires according to the invention is due to the lower tread depth and the lower

[0060] Groove empty volume compared to the prior art commercial vehicle tires per axle 325g / t, for the 3-axle semi-trailer 108g / t, in example 2 for the commercial vehicle tires according to the invention 560g / t and 187g / t for the 3-axle semi-trailer, in example 3 for the commercial vehicle tires according to the invention 790g / t and 263g / t for the 3-axle semi-trailer.

[0061] Table 1 (Example 1) 202404114 Table 3 (Example 3) 202404114

[0062] (1): per tire, which corresponds to the benefit per axle

[0063] 202404114

[0064] Reference symbol list

[0065] 1 tread

[0066] 2 circumferential ribs

[0067] 3 circumferential groove

[0068] 4 Shoulder flank

[0069] 5 semi-trailer truck

[0070] 6 semi-trailers

[0071] 7 front trailer axle

[0072] 8 middle trailer axle

[0073] 9 rear trailer axle

[0074] 10, 12 Steering axle

[0075] 11, 13 Drive axle

[0076] 14 Trailing axle bi width (of the circumferential groove 3)

[0077] Li > . Line

[0078] Fi area

Claims

202404114 Patent claims 1. Commercial vehicle tire with a tread (1) having shoulder flanks (4) and with several circumferential grooves (3) which divide the tread (1) into circumferential ribs (2) and of which at least the intended tread depth (T) is formed and which is the deepest circumferential groove (3) of all circumferential grooves (3), wherein the tread (1) has a gross tread volume VB which is located between the circumferentially running tread periphery and a circumferentially running surface (Fi) extending parallel to the tread periphery in the tread (1) and radially inwardly contacting the deepest circumferential groove (3) of the circumferentially running surface (Fi) which extends laterally to the shoulder flanks (4), and wherein all profile negatives formed within the gross tread volume VB, such as the circumferential grooves (3) and other grooves and cuts, have a total groove empty volume VR,which amounts to 1% to 9% of the gross tread volume VB, characterized by the fact that the commercial vehicle tire has a tread depth (T) of 4.00 mm to 9.00 mm in the tread.

2. Commercial vehicle tire according to claim 1, characterized in that it is type-approved as FRT (Free Rolling Tyre) in accordance with UN / ECE Regulation No. 54 and is marked as FRT.

3. Commercial vehicle tire according to claim 1 or 2, characterized in that it has a load index > 156.

4. Commercial vehicle tire according to one of claims 1 to 3, characterized in that the tread depth (T) is at most 8.00 mm, in particular at most 7.00 mm and 202404114 particularly preferably at most 6.00 mm, in particular at most 5.00 mm.

5. Commercial vehicle tire according to one of claims 1 to 4, characterized in that the groove empty volume VR is at most 8%, in particular at most 7% and particularly preferably at most 6%, in particular at most 5%.

6. Commercial vehicle tire according to one of claims 1 to 4, characterized in that the tread depth (T) is at most 9.00 mm and the groove empty volume VR is at most 7% or at most 8%.

7. Commercial vehicle tire according to one of claims 1 to 4, characterized in that the tread depth (T) is at most 9.00 mm and the groove empty volume VR is at most 5% or at most 6%.

8. Commercial vehicle tire according to one of claims 1 to 4, characterized in that the tread depth (T) is at most 8.00 mm and the groove empty volume VR is at most 6% or 7%.

9. Commercial vehicle tire according to one of claims 1 to 4, characterized in that the tread depth (T) is at most 8.00 mm and the groove empty volume VR is at most 5%.

10. Use of commercial vehicle tires according to one or more of claims 1 to 9 on a semi-trailer (6) having three free-rolling axles (7, 8, 9), offered or offered for sale as a new vehicle, exclusively on the middle axle (8) of the three free-rolling axles (7, 8, 9), or on a tractor unit having a free-rolling trailing axle (14), such as a semi-trailer tractor (5), or a bus having a free-rolling trailing axle, in each case exclusively on the free-rolling trailing axle 202404114 11. Three-axle semi-trailer (6), offered or offered for sale as a new vehicle, with three free-rolling axles, a front axle (7), a middle axle (8) and a rear axle (9), wherein commercial vehicle tires are mounted on each of these three axles (7, 8, 9), wherein commercial vehicle tires according to one or more of claims 1 to 8 are mounted on the middle axle (8) and wherein commercial vehicle tires are mounted on the front and rear axles (7, 9) having a tread depth (T) in the running surface that is at least 1.00 mm greater than the tread depth (T) of the running surfaces (1) of the commercial vehicle tires mounted on the middle axle (8).

12. Three-axle semi-trailer (6) according to claim 11, characterized in that commercial vehicle tires are mounted on the front and rear axles (7, 9) which have a tread depth (T) in the running surface that is at least 1.50 mm, preferably at least 2.00 mm and up to 6.00 mm, greater than the tread depth (T) of the commercial vehicle tires on the middle axle (8).

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