UN R172 Supplement 2 (00 series) · UNECE Regulation No. 172 (ECE R172) — Uniform provisions concerning the approval of retreaded tyres with regard to their snow performance and/or classification as traction tyre.
UN R172 — Supplement 2 to the 00 series of amendments
Supplement 1 → 2
- What changed
- Paragraph 6.4. now gives additional requirements for a special use tyre of class C1 to be classified as a ‘professional off-road tyre’. The tyre must have a tread depth ≥ 11 mm, a void-to-fill ratio ≥ 35 per cent and a speed category up to 160 km/h.
- Paragraph 12.1. covers type approvals based on snow performance tests in Annex 7 to UN Regulation No. 117 with SRTT19.5 or SRTT22.5 as reference tyre. As from 1 September 2030, Contracting Parties “shall not be obliged to grant” them.
- Paragraph 12.3. adds that Contracting Parties must continue to accept existing type approvals of class C3 tyres first issued before 1 September 2030. These approvals are based on the snow performance test described in Annex 7 to UN Regulation No. 117, using either SRTT19.5 or SRTT22.5. The rule applies notwithstanding paragraphs 12.1. and 12.2.
- Why
- The requirements for the classification of class C1 tyres were erroneously cancelled by the amendments to paragraph 6.4. made by Supplement 1. The amendment reintroduces them.
- Section 8 referred to Appendix 1 of the 1958 Agreement. However, the conformity of production procedures are contained in Schedule 1 of that Agreement.
- Based on Revision 3 of the 1958 Agreement, the extension number is already included in the approval number.
Q1What changed11 changes
Class C1 tyres as professional off-road tyres (para. 6.4.)
Paragraph 6.4. has a new item (a) for class C1 tyres. It gives the additional requirements for a special use tyre of class C1 to be classified as a ‘professional off-road tyre’. The tyre must have a tread depth ≥ 11 mm, a void-to-fill ratio ≥ 35 per cent and a speed category up to 160 km/h. The former items (a) and (b) for class C2 and class C3 tyres are renumbered as (b) and (c).
Snow performance tests with SRTT19.5 and SRTT22.5 (paras. 12.1. and 12.3.)
Paragraph 12.1. covers type approvals based on snow performance tests in Annex 7 to UN Regulation No. 117 with SRTT19.5 or SRTT22.5 as reference tyre. As from 1 September 2030, Contracting Parties “shall not be obliged to grant” these type approvals. Before, the text said that they “shall not grant” them. Paragraph 12.3. adds that Contracting Parties must continue to accept existing type approvals of class C3 tyres based on these tests. They must also continue to grant extensions to these approvals. Both apply to approvals first issued before 1 September 2030, notwithstanding paragraphs 12.1. and 12.2.
Definition of “Supplier of the tread used for retreading process” (para. 2.2.)
The definition in paragraph 2.2. now ends “for ensuring the conformity of production of the supplied tread”. Before, it ended “for ensuring the conformity of production”.
Conformity of production: Schedule 1 of the Agreement (para. 8.)
The conformity of production procedures must comply with those set out in the Agreement, Schedule 1 (E/ECE/324-E/ECE/TRANS/505/Rev.3). Before, the text referred to Appendix 1 instead of Schedule 1.
Approval number in the communication (Annex 1)
In the communication in Annex 1, the line “Approval No.:” no longer has a separate “Extension No.:” field.
Q2Why it changed
- Proposed by
- Experts from the European Tyre and Rim Technical Organization (ETRTO)
- Working party
- GRBP, 83rd session (February 2026)
Reasons
The requirements for the classification of tyres of class C1 were erroneously cancelled by the amendments to paragraph 6.4. made by Supplement 1. The amendment reintroduces those requirements.
Sources (2)
“The requirements for the classification of tyres of class C1 were erroneously cancelled by the amendments to paragraph 6.4. made by Supplement 1.”
“The proposed amendment reintroduces those requirements”
The first paragraph of section 8 refers to Appendix 1 of the 1958 Agreement. However, the conformity of production procedures are contained in Schedule 1 of that Agreement.
Sources (2)
“The first paragraph of section 8 refers to Appendix 1 of the 1958 Agreement.”
“However, the Conformity of production procedures are contained in Schedule 1 of that Agreement.”
Based on Revision 3 of the 1958 Agreement, the extension number is already included in the approval number.
Source
“Based on the Revision 3 of the 1958 Agreement, the extension number is already included in the approval number.”
Proposer's reason (informal document GRBP-83-18)
The definition of “supplier of the tread used for the retreading process” is amended to clarify the supplier's responsibility. The aim is to make clear that the supplier is responsible to assure the conformity of production of the supplied tread. This is with respect to the performance and/or classification of the type of retreaded tyre approved under this Regulation.
Submitted by Experts of ETRTO. Working party adoption: ECE/TRANS/WP.29/GRBP/83, para. 32.
Source
“has been amended to clarify that he is responsible to assure the conformity of production of the supplied tread with respect to the performance and/or classification of the type of retreaded tyre approved under this Regulation”
Proposer's reason (informal document GRBP-83-18)
The proposal for paragraph 12.1. considers that it is up to the Contracting Parties to decide whether to grant the type approvals. The amendment to paragraph 12.3. considers the acceptance of existing type approvals in addition to the grant of their extensions. For this reason, the reference to paragraph 12.2. is added.
Submitted by Experts of ETRTO. Working party adoption: ECE/TRANS/WP.29/GRBP/83, para. 32.
Sources (3)
“It is proposed to amend the paragraph 12.1. by considering that is up to the Contracting Parties deciding whether grant or not the type approvals.”
“Amendment to paragraph 12.3. has been tuned by considering the acceptance of existing type approvals in addition to grant their extension.”
“Consequently the reference to paragraphs 12.2. has been added.”
Document trail
- 2025-11ProposalECE/TRANS/WP.29/GRBP/2026/11Proposal by the experts from ETRTO
- —RevisedGRBP-83-17Shortened proposal to replace GRBP/2026/11
- —RevisedGRBP-83-18Expanded proposal to replace GRBP/2026/11
- —Working party adoptsECE/TRANS/WP.29/GRBP/83GRBP session report, para. 32
- 2026-04Sent to WP.29ECE/TRANS/WP.29/2026/99Text that GRBP sent to WP.29 and AC.1
- 2026-06-24WP.29 adoptsECE/TRANS/WP.29/1192Adopted at the 199th session (session report, para. 103)
- PendingIn forceDate not yet known
Q3Who is affected
Vehicle manufacturer
- No direct action for this role.
Component supplier
- Check class C1 special use tyres against new item (a) before you classify them as ‘professional off-road tyre’.
Technical service / Approval authority
- For ‘professional off-road tyre’ classification of class C1 tyres, check tread depth, void-to-fill ratio and speed category against item (a).
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ⓘ This report gives advice only. It is not legal or type-approval advice.