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UN R54 Supplement 26 (00 series) · UNECE Regulation No. 54 (ECE R54) — Uniform provisions concerning the approval of pneumatic tyres for commercial vehicles and their trailers.

UN R54 — Supplement 26 to the 00 series of amendments

Supplement 25 → 26

Adopted at the WP.29 190th sessionEntry into force 2024-01-05
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What changed
  • New paragraph 4.1.6.1. says that the speed category symbol E can be used only for the additional service description. In paragraph 2.31.2., symbol E corresponds to 70 km/h.
  • Annex 7, paragraph 2.1. now uses a test drum “of at least 1.70 m ± 1 per cent in diameter”. For a test drum diameter larger than 1,700 mm ± 1 per cent, the percentage of test load must be increased.
  • The table in paragraph 2.20.4.1. adds the nominal rim diameter codes 32, 34, 36, 38, 40 and 42, and 26.5, 28.5 and 30.5.
Why
  • There is a market request to mark the tyres of commercial vehicles often used at 70 km/h with an additional service description with symbol E.
  • For practical reasons, most tyres with very large overall diameters are regularly tested on drums with a diameter of 3 m or even larger.
  • Special use tyres with rim diameters larger than those in the table have been announced in the European market for N3G special purpose vehicles.

Q1What changed28 changes

Snow tyre definition and special use tyre blocks (paras. 2.5.2. and 6.3.1.)

In the definition of “snow tyre” (para. 2.5.2.), “structure” is now “construction”. The better performance is now “in mud and/or snow conditions” in place of “in snow conditions”. The ability of the tyre is now to “initiate and control vehicle motion” in place of “initiate or maintain vehicle motion”. In paragraph 6.3.1., the word “blocks” now has an asterisk. A new note reads: “* blocks may be shaped as lugs and cleats”.

"Snow tyre" means a tyre whose tread pattern, tread compound or structure construction is primarily designed to achieve in mud and/or snow conditions a performance better than that of a normal tyre with regard to its ability to initiate or maintain and control vehicle motion;
In order to be classified as a "special use tyre" a tyre shall have a block tread pattern in which the blocks * are larger and more widely spaced than for normal tyres and have the following characteristics:
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Nominal rim diameter codes (para. 2.20.4.1.)

The table in paragraph 2.20.4.1. adds the nominal rim diameter codes 32, 34, 36, 38, 40 and 42. Their values of the “d” symbol are 813, 864, 914, 965, 1016 and 1067 mm. The table also adds the codes 26.5, 28.5 and 30.5, with values of 673, 724 and 775 mm.

32 813 34 864 36 914 38 965 40 1016 42 1067 26.5 673 28.5 724 30.5 775

Speed category symbol E and the additional service description (paras. 2.31.2., 2.36. and 4.1.6.1.)

The table of speed categories in paragraph 2.31.2. now includes speed category symbol E, with a corresponding speed of 70 km/h. New paragraph 4.1.6.1. says that the speed category symbol E can be used only for the additional service description. New paragraph 2.36. defines the “additional service description”. It is marked within a circle and identifies a special type of service (load-capacity index or indices and speed category symbol). The tyre type is also allowed to operate at this service in addition to the applicable load variation with speed (see Annex 8).

Speed-category symbolSpeed category symbol E 70
The speed category symbol E can be used only for the additional service description.
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Endurance test for an additional service description (paras. 6.2.5. and 6.2.5.1.)

Paragraph 6.2.5. now applies to the approval of a type of tyre which has an additional service description. Before, the text said “a load/speed combination in addition to the one that is subject to the variation of load with speed”. Under new paragraph 6.2.5.1., tyres marked with an additional service description can be exempted from performing an additional load/speed test, under three conditions. First, the difference in load is not greater than 2 per cent with respect to a load/speed combination applicable to the nominal speed category symbol. Second, the speed category of the additional service description differs from the speed category of the nominal service description. Third, no second test inflation pressure is marked for the additional service description.

Where application is made for the approval of a type of tyre which has a load/speed combination in addition to the one that is subject to the variation of load with speed given in the table in Annex 8an additional service description, the endurance test prescribed in paragraph 6.2.1. above shall also be carried out on a second tyre of the same type at the additional load/speed combination and the applicable inflation pressure. At the option of the tyre manufacturer, one test at the highest load index, the highest speed symbol and the lowest test inflation pressure indicated may be submitted.
Tyres marked with an additional service description for which the load-capacity represents a difference in load not greater than 2 per cent with respect to a load/speed combination applicable to the nominal speed category symbol (see Annex 8) can be exempted from performing an additional load/speed test, provided that the speed category of the additional service description differs from the speed category of the nominal service description and that there is no second test inflation pressure marked for the additional service description.

Endurance-test programme (Annex 7, Appendix 1)

The endurance-test programme now has a row for speed category symbol E, both for load-capacity index 122 or more and for 121 or less. In these rows, the test-drum speed is 32 km/h for radial-ply and for diagonal (bias-ply) tyres. For load-capacity index 122 or more, a new row for symbol N gives a radial-ply test-drum speed of 80 km/h. The table now says “load-capacity index” in place of “load index”, and “km/h” in place of “km.h-1”.

Load Load-capacity index Load placed on the wheel as a percentage of the load corresponding to the load load-capacity index Radial-ply km.h-1km/h Diagonal (bias-ply) km.h-1km/h 7 h.7 h 16 h.16 h 24 h.24 h E 32 32 -— -— N 80 — E 32 32 4 h. 6 h. 4 h 6 h 24 h -— -—
(2) Tyres with load index 122 or more, speed category symbols N or P and the additional marking "LT", or "C", referred to in paragraph 3.1.14. of this Regulationregulation, shall be tested with the same programme as specified in the above table for tyres with load index 121 or less.

Test drum diameter (Annex 7, paragraph 2.1., and Appendix 1, note (3))

In Annex 7, paragraph 2.1., the test drum is now “of at least 1.70 m ± 1 per cent in diameter”, in place of “1.70 m ± 1 per cent in diameter”. New note (3): for a test drum diameter larger than 1,700 mm ± 1 per cent, the “percentage of test load” must be increased. In the formula F1 = K∙F2, F1 is the percentage of load to be applied for the test drum. F2 is the percentage of load from the table for the reference test drum of 1,700 mm. For example, K = 1 for a test drum diameter of 1,700 mm. For a 3,000 mm drum and a 1,500 mm tyre diameter, K = 1.12.

Mount the tyre-and-wheel assembly on the test axle and press it against the outer face of a smooth power-driven test drum of at least 1.70 m ± 1 per cent in diameter having a surface at least as wide as the tyre tread.
(3) In case of a test drum diameter larger than 1,700 mm ± 1 per cent, the above "percentage of test load" shall be increased as follows:
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Overall width measurement, scope and R.E.3 footnote (Annex 6, paragraph 4., and paragraph 1)

In Annex 6, paragraph 4., the overall width is now measured at six equally-spaced points, without the words “by caliper”. The Scope in paragraph 1 now says that the Regulation does not apply to tyre types identified by “nominal speed category symbols” corresponding to speeds below 80 km/h. Before, it said “speed category symbols”. The footnote that refers to the Consolidated Resolution on the Construction of Vehicles (R.E.3.) no longer gives “para. 2.” and the web address.

The overall width is measured by caliper at six equally-spaced points, account being taken of the thickness of the protective ribs or bands. The highest measurement so obtained is taken as the overall width.
This Regulation covers new pneumatic tyres designed primarily for vehicles of categories M2, M3, N, O3 and O4., ,. However, it does not apply to tyre types identified by nominal speed category symbols corresponding to speeds below eighty (80) km/h.
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Q2Why it changed

Proposed by
Experts from the European Tyre and Rim Technical Organization (ETRTO)
Working party
GRBP, 77th session (February 2023)

Reasons

  • “Special use” tyres with nominal rim diameters larger than those in the table have been announced in the European market. They have been announced as original equipment of N3G special purpose vehicles. The proposal adds new codes to paragraph 2.20.4.1. to allow the type approval of these tyres.

    Sources (3)
    ““Special use” tyres with nominal rim diameters larger than those listed in the present table”
    “have been announced in the European market as original equipment of N3G "special purpose vehicles" (i.e. special high speed self-propelled vehicles for agricultural and forestry use, like wood choppers).”
    “In order to allow the type approval of tyres equipping such "special purpose vehicles" it is proposed to add to paragraph 2.20.4.1. the nominal rim diameter codes”

  • Existing multi-purpose tyres, classified as “special use tyres”, have a tread pattern with lugs or cleats in addition to those with blocks. The change to paragraph 6.3.1. clarifies that lugs and cleats are possible shapes of the blocks. The snow tyre definition now clarifies that snow tyres are suitable not only in snow conditions but also on mud. “Controlling vehicle motion” is a more general concept than “maintain vehicle motion”.

    Sources (4)
    “Existing multi-purpose tyres (MPT) (classified as “special use tyres” as per paragraphs 2.5.3. and 3.1.13.), already type approved since years, have a tread pattern with lugs or cleats in addition to those with blocks”
    “It is proposed to amend paragraph 6.3.1. by clarifying that lugs and cleats are possible shapes of the mentioned blocks.”
    “The definition of "snow tyre" is amended to clarify that "snow tyres" are not only suitable for the use in snow conditions but also on mud”
    “by replacing the term "maintain vehicle motion" (i.e. keeping the vehicle speed and direction of movement constant) by a more general concept of "controlling vehicle motion"”

  • Some commercial vehicles are often used in the market at a reduced speed of 70 km/h. There is a market request to mark their tyres with an additional service description with speed category symbol E. The proposal allows symbol E but restricts it to the additional service description. For the additional service descriptions in paragraph 6.2.5.1., the proposal is not to perform the additional load/speed test. The reason given is that the load-capacity approximates the reduction or the increase in percentage of the nominal load/speed combination with a negligible difference.

    Sources (5)
    “Some commercial vehicles are often used in the market at a reduced speed of 70 km/h with a load-capacity of the tyres increased as per load/speed combination defined in the table of Annex 8.”
    “There is a market request to give clear information to the end‐user by marking the tyres fitted on these vehicles with an additional service description which consider the speed category symbol E”
    “it is therefore proposed to allow the use of speed category symbol E but to restrict it to the “additional service description”.”
    “In the case of additional service descriptions mentioned in paragraph 6.2.5.1., it is proposed not to perform the additional load/speed test”
    “because the load-capacity approximates with a negligeable difference the reduction or the increase in percentage of the nominal load/speed combination applicable to the nominal speed category symbol”

  • 32 km/h is already a floor value for the test-drum speed for diagonal tyres. ETRTO proposes, for safety reasons, the same test-drum speed for E as for F speed category symbol tyres: 32 km/h. Type approval applications for symbol N were made for radial tyres with load capacity index 122 or more and without “LT” or “C”. Annex 7, Appendix 1 did not describe the load/speed endurance test procedure for these tyres. The proposal adds testing conditions to Annex 7, Appendix 1 to harmonize the test procedure for these tyres.

    Sources (5)
    “Considering that 32 km/h is already a floor value for the test-drum speed for diagonal tyres ETRTO proposes not to apply to E speed category symbol tyres the linear decrease of the test-drum speed”
    “by keeping, for safety reasons, the same test-drum speed as for F speed category symbol tyres, i.e., 32 km/h.”
    “Type approval applications for radial tyres with load capacity index greater or equal to 122 and without the additional marking "LT", or "C" have been done in the past for the speed category symbol N”
    “for which the load/speed endurance test procedure is not described in Annex 7, Appendix 1.”
    “In order to harmonize the test procedure to be used for the type approval of such tyres, it is proposed to amend the Annex 7, Appendix 1 by introducing testing conditions”

  • Testing tyres with very large overall diameters, sometimes over 2 m, on a test drum of 1.70 m ± 1 % would be unpracticable. For practical reasons, most of those tyres are regularly tested on drums with a diameter of 3 m or even larger. The new conditions for other drum diameters are copied from UN Regulation No. 106, Annex 9, paragraph 3.4.1. Removing the words “by caliper” explicitly allows other technical measurement solutions for the tyre overall width.

    Sources (4)
    “Testing tyres with very large overall diameters, sometimes over 2 m, on a test drum with a diameter of 1.70 m ± 1 % would be unpracticable.”
    “For practical reasons most of those tyres are regularly tested on drums with a diameter of 3 m or even larger.”
    “The proposed requirements are copied from regulation UN Regulation No. 106, Annex 9, paragraph 3.4.1.”
    “It is proposed to explicitly allow other technical measurement solutions of the tyre overall width by removing the words “by caliper” which fix a technical limitation.”

Document trail

  1. 2022-11ProposalECE/TRANS/WP.29/GRBP/2023/11Proposal by ETRTO
  2. —RevisedGRBP-77-24Proposal text transmitted by ETRTO for the 77th GRBP session
  3. —Working party adoptsECE/TRANS/WP.29/GRBP/75Session report, para. 14
  4. 2023-03Sent to WP.29ECE/TRANS/WP.29/2023/73Text that GRBP sent to WP.29 and AC.1
  5. 2023-06WP.29 adoptsECE/TRANS/WP.29/1173Adopted at the 190th session (session report, para. 165)
  6. 2024-01-05In forceC.N.13.2024.TREATIES-XI.B.16.54UN depositary notification

Q3Who is affected

Vehicle manufacturer

  • No direct action for this role.

Component supplier

  • Use the speed category symbol E only for the additional service description (para. 4.1.6.1.).
  • Check the paragraph 6.2.5.1. conditions for exempting tyres marked with an additional service description from the additional load/speed test.

Technical service / Approval authority

  • For test drum diameters larger than 1,700 mm ± 1 per cent, increase the percentage of test load as F1 = K∙F2.
  • Test normal tyres with symbol E at 32 km/h drum speed (note (1) covers special-use tyres).
  • Test normal radial tyres (load-capacity index 122 or more, symbol N) at 80 km/h drum speed, unless note (2) applies.

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ⓘ This report gives advice only. It is not legal or type-approval advice.

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