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UN R108 Supplement 2 (01 series) · UNECE Regulation No. 108 (ECE R108) — Uniform provisions concerning the approval for the production of retreaded pneumatic tyres for motor vehicles and their trailers.

UN R108 — Supplement 2 to the 01 series of amendments

Supplement 1 → 2

Adopted at the WP.29 199th sessionEntry into force not yet known
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What changed
  • The definition in paragraph 2.48. is deleted, and paragraph 2.51. now defines “Material supplier” in place of “Material manufacturer / material supplier”.
  • Paragraphs 4.1.5.3.2.1., 4.1.5.3.2.2. and 4.1.5.3.2.3. are deleted, and paragraph 4.1.5.3.2. has one example table for the list of tyres for use in severe snow conditions.
  • For special use tyres, the coefficient “b” in paragraph 7.1.5.1.4. is 1.06 for radial tyres and 1.09 for diagonal (bias-ply) and bias belted tyres.
Why
  • The definition in paragraph 2.48. is too restrictive, because not all retreaded tyres from approved retreading units are type-approved pursuant to UN Regulation No. 172.
  • The definition in paragraph 2.51. describes the material supplier and not the material manufacturer.
  • The cases in paragraphs 4.1.5.3.2.1., 4.1.5.3.2.2. and 4.1.5.3.2.3. are already handled in UN Regulation No. 172.

Q1What changed60 changes

Definitions of the tread supplier and the material supplier (paras. 2.48. and 2.51.)

Paragraph 2.48. is deleted. It defined the “Supplier of the tread used for retreading process”. Paragraph 2.51. now defines “Material supplier” in place of “Material manufacturer / material supplier”. The rest of the definition is the same: the person or body who provides to the retreader the retreading or repair materials. The former paragraph 2.57. is now paragraph 2.48., and the former paragraphs 2.58. to 2.61. are now paragraphs 2.57. to 2.60.

"Supplier of the tread used for retreading process" means the person or body who is responsible to the Type Approval Authority for all aspects of the type-approval under UN Regulation No. 172.
"Material manufacturer / material supplier" means the person or body who provides to the retreader the retreading or repair materials.
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“Material supplier” in place of the manufacturer (paras. 6.5.3., 6.5.8., 6.6.1., 6.6.3., 6.6.4. and 6.6.5.)

Paragraphs 6.5.3., 6.5.8., 6.6.1., 6.6.3., 6.6.4. and 6.6.5. now refer to the “material supplier”. Before, they referred to the manufacturer of the material, alone or as an alternative to the supplier.

Where precured material is to be used the contours of the prepared area shall meet the requirements of the material manufacturersupplier.
Exposed steel parts shall be treated as soon as possible with appropriate material as defined by the manufacturer material supplier of that appropriate material.
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Retreader and tyre manufacturer wording (paras. 3.2.7. and 3.6., Annex 7, para. 2.4.)

Paragraph 3.2.7. now lists the inscription M+S or M.S. or M&S, and the inscription MS is deleted. This applies if the tyre is classified in the category of use “snow tyre”. It also applies to a “special use tyre” declared as complying also with the definition given in paragraph 2.3.2. The retreader, in place of the tyre manufacturer, now makes this declaration at paragraph 4.1.5.3.1. Paragraph 3.6. now says “original tyre manufacturer's specifications” in place of “original manufacturer’s specifications”. In Annex 7, paragraph 2.4., a test-room temperature higher than 20°C to 30°C needs the retreader's agreement, in place of the tyre manufacturer or retreader.

The inscription M+S or MS or M.S. or M&S if the tyre is classified in the category of use "snow tyre" or if the tyre is classified in the category of use "special use tyre" when declared by the tyre manufacturer retreader at paragraph 4.1.5.3.1. as complying also with the definition given in paragraph 2.3.2.
As far as any of the original manufacturer’s tyre manufacturer's specifications are still legible after the tyres have been retreaded, they shall be regarded as specifications of the retreader for the retreaded tyre. If these original specifications do not apply after retreading they shall be completely removed.
1 more change in this group — open in Compare

List of tyres for use in severe snow conditions (para. 4.1.5.3.2.)

Paragraph 4.1.5.3.2. now has one example table for the list of tyres classified as tyre for use in severe snow conditions. The example table shows UN Regulation No. 172 approval numbers (TA) by tyre size designation and by retreader tread pattern (TPR). Paragraphs 4.1.5.3.2.1., 4.1.5.3.2.2. and 4.1.5.3.2.3. are deleted, with their example tables and notes. Before, these paragraphs set out the list for the retreaded tyres covered by paragraphs 6.6.3.1., 6.6.3.2. and 6.6.3.3., one case each.

The list of tyres classified as tyres for use in severe snow conditions.The list of tyres classified as tyre for use in severe snow conditions. The list shall clearly identify the tyres in order to make the relevant link with the list(s) quoted in paragraph 6.4.4.1. b).
The following table is an example:
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Changes to paras. 6.6.3.1., 6.6.3.2. and 6.6.3.3., including tread values

Paragraph 6.6.3.1. now covers retreaded tyres type approved pursuant to UN Regulation No. 172. Before, it covered only such tyres produced by using pre-cured tread and/or mould cure process with the same tread pattern not covered by paragraph 6.6.3.2. The retreader must now make sure that the material supplier(s) of tread(s) used for retreading process give the listed documents. The former paragraphs 6.6.3.2. and 6.6.3.3. are deleted, and the former paragraph 6.6.3.4. is now paragraph 6.6.3.3. New paragraph 6.6.3.2. applies to retreaded tyres categorized as “special use tyres”. The retreader must make sure the supplier(s) of the tread(s) give the values of tread depth and void to fill ratio pertinent to each tread.

For retreaded tyres produced by using pre-cured tread and/or by using mould cure process with the same tread pattern not covered by paragraph 6.6.3.2. and type approved pursuant to UN Regulation No. 172, the retreader shall ensure that the material supplier(s) of the tread(s) used for retreading process provides to the Type Approval Authority and the Technical Service issuing the approval according to this regulation and optionally to the retreader:
A copy of the UN Regulation No. 172 certificate(s), as issued by the relevant Type Approval Authority.;
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Outer diameter of special use tyres and snow tyres (paras. 7.1.5.1.4. and 7.1.5.2.)

The table of the coefficient “b” in paragraph 7.1.5.1.4. has a new row for special use tyres. The values are 1.06 for radial tyres and 1.09 for diagonal (bias-ply) and bias belted tyres. In paragraph 7.1.5.2., the outer diameter of tyres of the category of use “snow tyre” must not exceed Dmax,snow = 1.01 • Dmax. This value is rounded to the nearest mm, and Dmax is the maximum outer diameter established for normal use tyres in conformity with the above. Before, for snow tyres the maximum outer diameter (Dmax) calculated in paragraph 7.1.5.1. could be exceeded by not more than 1 per cent.

for special use tyres 1.06 1.09
For snow tyres the maximum outer diameter (Dmax) calculated in paragraph 7.1.5.1. may be exceeded by not more than 1 per cent.For tyres of the category of use “snow tyre” the outer diameter shall not exceed the following value
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Other text changes (paras. 2.14.1., 6.7.4. and 9., Annex 1)

Paragraph 2.14.1. no longer repeats the sentence on the central zone of the tread. Paragraph 6.7.4. now says “in paragraph 7. or to those given in Annex 5 to this Regulation”. Paragraph 9. now refers to Schedule 1 of the Agreement, in place of Appendix 2, for the conformity of production procedures. In the Annex 1 communication, item 1. now asks for the “Retreader's name and address” in place of the “Retreaders's name or trade mark”. The “Extension No.” entry is deleted from the “Approval No.” line.

"Principal grooves" means the wide tread grooves positioned in the central zone of the tyre tread. The central zone is the area on the tread which comprises of 75 per cent of the width of the tread measured symmetrically from the centre line. The central zone is the area on the tread which comprises of 75 per cent of the width of the tread measured symmetrically from the centre line.
After retreading, the dimensions of the retreaded tyre, when measured in accordance with annex 6 to this Regulation, must conform either to dimensions calculated according to the procedures in paragraph 7 . or to annex those given in Annex 5 to this Regulation.
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Q2Why it changed

Proposed by
Experts from the European Tyre and Rim Technical Organization
Working party
GRBP, 83rd session (February 2026)

Reasons

  • The definition of the “supplier of the tread used for retreading process” in paragraph 2.48. is too restrictive. Not all retreaded tyres produced by retreading units approved pursuant to this Regulation are type-approved pursuant to UN Regulation No. 172. The definition of “material supplier” in paragraph 2.51. covers also the supplier of tread used for producing those type-approved tyres. This definition describes the material supplier and not the material manufacturer. For this reason, the proposal also cancels the references to the material manufacturer as an alternative to the material supplier.

    Sources (3)
    “is too restrictive because not all the retreaded tyres produced by retreading units approved pursuant to this Regulation are type-approved pursuant to UN Regulation No. 172”
    “covers also the supplier of tread used for producing retreaded tyres type-approved pursuant to UN Regulation No 172.”
    “because the definition given in this paragraph describes this market operator and not the material manufacturer.”

  • The proposal simplifies the list of tyres classified as tyre for use in severe snow conditions. The cases in paragraphs 4.1.5.3.2.1., 4.1.5.3.2.2. and 4.1.5.3.2.3. are already handled in UN Regulation No. 172. A simple list with the UN Regulation No. 172 type approval number, the size and the retreader's trade description/commercial name covers all the needed information.

    Sources (2)
    “In fact, the various cases currently specified in paragraphs 4.1.5.3.2.1., 4.1.5.3.2.2. and 4.1.5.3.2.3. are already handled in UN Regulation No. 172.”
    “a simple list reporting just the type approval number of UN Regulation No. 172 associated to the size and the trade description/commercial name given by the retreader to the retreaded tyre cover all the needed information.”

  • A new paragraph clarifies that suppliers of tread material for retreading special use tyres must give the retreader its void to fill ratio. In paragraph 7.1.5.1.4., the coefficient b is added for special use tyres.

    Sources (2)
    “It is proposed to introduce a paragraph clarifying that the supplier of tread material dedicated to the retreading of tyres categorized as special use tyres shall provide to the retreader the void to fill ratio pertinent to such tread material.”
    “In paragraph 7.1.5.1.4. the coefficient b is added for special use tyres.”

  • Paragraph 7.1.5.2. is aligned to paragraph 6.1.5.4. of UN Regulation No. 30.

    Source
    “Paragraph 7.1.5.2. is aligned to paragraph 6.1.5.4. of UN Regulation No. 30”

  • Proposer's reason (informal document GRBP-83-14-Rev.1)

    Section 9 referred to Appendix 2 of the 1958 Agreement, but the conformity of production procedures are in Schedule 1 of that Agreement. Based on Revision 3 of the Agreement, the extension number is already included in the approval number.

    Submitted by Experts of ETRTO. Working party adoption: ECE/TRANS/WP.29/GRBP/83, para. 18.

    Sources (2)
    “The first paragraph of section 9 refers to Appendix 2 of the 1958 Agreement. However, the Conformity of production procedures are contained in Schedule 1 of that Agreement.”
    “Based on Revision 3 of the Agreement, the extension number is already included in the approval number.”

Document trail

  1. 2025-11ProposalECE/TRANS/WP.29/GRBP/2026/9Proposal by the experts from the European Tyre and Rim Technical Organization
  2. —RevisedGRBP-83-13-Rev.1Proposal to replace GRBP/2026/9, transmitted by the experts of ETRTO
  3. —RevisedGRBP-83-14-Rev.1Full text of the paragraphs in GRBP-83-13, transmitted by the experts of ETRTO
  4. —Working party adoptsECE/TRANS/WP.29/GRBP/83Session report, para. 18
  5. 2026-04Sent to WP.29ECE/TRANS/WP.29/2026/93Text that GRBP sent to WP.29 and AC.1
  6. 2026-06-24WP.29 adoptsECE/TRANS/WP.29/1192Adopted at the 199th session (session report, para. 103)
  7. PendingIn forceDate not yet known

Q3Who is affected

Vehicle manufacturer

  • No direct action for this role.

Component supplier

  • In your application for approval, update the list of tyres classified as tyre for use in severe snow conditions.
  • For tyres type approved pursuant to UN Regulation No. 172, make sure tread material suppliers give the paragraph 6.6.3.1. documents.
  • For special use tyres, use coefficient “b” 1.06 for radial tyres and 1.09 for diagonal (bias-ply) and bias belted tyres.
  • Check snow tyre outer diameter: at most 1.01 • Dmax of normal use tyres, rounded to the nearest mm.

Technical service / Approval authority

  • Check special use tyre outer diameters with coefficient “b”: 1.06 for radial, 1.09 for diagonal (bias-ply) and bias belted tyres.
  • Check snow tyre outer diameters against 1.01 • Dmax of normal use tyres, rounded to the nearest mm.

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

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