TA-48-02 updates TA-47-02. C2 tyre abrasion rate index vehicle method uses a convoy of up to 4 vehicles with single tyres, GVW up to 3.5T, FWD, loaded 60%–74% of tyre nominal load with 50/50 front/rear distribution. Test distance is 10000 km at 80% nominal pressure. Reference tyres use 2 sets of test runs with C2 candidate SRTT and existing C1 SRTTs. 2025 testing in 235/65R16C and 205/65R16C sizes showed C2 tyres sensitivity to temperature similar to C1 tyres. 2026 plan repeats and extends 2025 testing to confirm reference tyres strategy, assess temperature sensitivity and pressure impact, and define validation plan.

The document presents a European heavy-duty vehicle and tyre market overview and C3 test method development status. The C3 tyre market is complex and diversified, with applications including long haul, regional, on/off road, winter, and urban use. A test concept has been developed focusing on road usage with 22.5" tyres, using convoys of up to four vehicles with defined acceleration standards, road distribution of 60% motorway and 40% regional roads, and tests per axle comparing candidate tyres to reference tyres. Current activities include assessment of reference tyres strategy, temperature sensitivity evaluation, and confirmation of test parameters for heavy trucks in N₃/O₃ configuration, with tests reaching 30,000 to 45,000 kilometres.

DEKRA Test Center examined whether vehicles fitted with SRTT impact tyre abrasion rates. Tests DEKRA #104 and DEKRA #41 compared SRTT Summer as candidate against SRTT Winter as reference, with abrasion indices of 1.18 and 1.19 respectively, showing no vehicle impact. Tests DEKRA 8 and DEKRA 9 showed abrasion rates of 45.1 mg/km/T and 45.0 mg/km/T respectively with no difference despite different vehicles. A 2024 convoy test with two Golf vehicles fitted with identical SRTT Summer showed a difference of 1 gram cumulated weight loss after 7,962 km (0.07 mg/km/T). DEKRA concludes the impact on abrasion level of the reference vehicle using SRTT is low or very low.

Existing C1 tyre-abrasion test methods cannot be directly applied to C3 tyres because vehicles equipped with C3 tyres are used differently. Japan is developing a vehicle test method using WHVC mode and plans to develop a drum test method based on test conditions and results. Test conditions will convert vehicle driving conditions representing the world into indoor drum test settings. C2 test method uses driving mode based on WLTP with fixed test load details, with verification tests using reference tyres. For C3, driving modes and test conditions are under preliminary investigation, with verification tests to be planned.

The agenda includes discussion of status of the work plan 2026 including the ITTAC proposal on tyre abrasion Convoy Method -Dual-Normalisation Framework (TA-45-08/Rev.1) and UTAC Tyre abrasion timeline Gantt (TA-46-03/Rev.1), development of the C1 tyre mileage potential metric and tread depth measurement prescription, and test method development status under C2 and C3.

ETRTO proposed three ways to estimate service life (TA-36-04): tread depth measurements, initial tread depth and abrasion index, and tread mass. JRC presented a service life index (TA-32-04) based on tread depth measurements and conducted a preliminary assessment of the second concept. Service life is estimated by linear extrapolation to 1.6 mm from tread measurements at test start and end. The Service life index is calculated as the ratio of candidate to reference tyre service life. Next steps include confirming the equation for service life via tyre characteristics and clarifying which tyre characteristics are needed.

The 47th session of the Task Force on Tyre Abrasion convened on 2 April 2026. The review committee prepared final consolidation of a new UN Regulation on Tyre Abrasion for WP.29. TFTA reviewed the workplan including data assessment, tyre batch use, and equivalence assessment governance. For C2, ETRTO presented findings on the vehicle test method at 10,000 km, while JASIC reported on indoor drum test development. Discussion on C3 Heavy-Duty Vehicle tyre applications was deferred. The next session is scheduled for 11 May 2026.

Proposal for a new UN Regulation on the approval of new pneumatic tyres of class C₁ conforming to UN R117 with regard to their tyre abrasion performance, excluding temporary-use spare tyres, tyres with rim diameter ≤13 or ≥25, competition tyres, tyres for vehicles of categories other than M₁–M₃, N₁–N₃, O₁–O₄, ice grip tyres, studded tyres, speed category less than 120 km/h, special use tyres, and road legal race tyres. Abrasion index limits are 1.00 for normal and snow tyres, with adjustments for specific groups. Approval requires marking with approval reference number and suffix (A1 or A2). Testing uses either vehicle test method on public open roads (~8000 km) or indoor drum test method (5044 km), with test facilities demonstrating equivalence per Annex 4. From 1 July 2028, stage 1 approvals required for new types; from 30 June 2030, all types. From 1 July 2033, stage 2 approvals required for new types; from 30 June 2035, all types. Until 1 July 2028, test results from tests performed

Proposal to amend document GRBP-83-32-Rev.1 to renumber Paragraph 6.1. as 6.1.1., renumber current Paragraph 6.1.1. as 6.1.2., introduce new paragraph 1.4. to Annex 3 Introduction, amend paragraph 2.8. with detailed abrasion index and level calculation equations, renumber items in Appendix 2, delete item 1.3. from Appendix 2, and amend item 1.3. in Appendix 6 to clarify transfer function applicability between circuit and drum test facilities.

Proposal to amend GRBP-83-32-Rev.1 to ensure robust tyre abrasion measurements regardless of test method used. Amendments modify paragraph 6.1 to require test facilities demonstrate equivalence per Annex 4 procedure; insert paragraphs 12.8 and 12.9 deeming inter-facility campaign participants equivalent for C₁ tyres and allowing pre-regulation test data through 1 July 2028; insert Annex 3 paragraph 1.4 requiring inter-facility equivalence assessment; amend Annex 3 paragraph 2.8 with abrasion calculation equations including transfer function coefficient; insert test report items 1.1–1.4 in Appendices 2 and 6; and insert new Annex 4 establishing equivalence demonstration procedure for vehicle and indoor drum test facilities.

JATMA submitted this position on the draft UN Regulation for tyre abrasion at GRBP-83-54. JATMA requests adoption of the indoor drum test method under conditions equivalent to the vehicle test method for type approval. JATMA proposes that the Generic transfer function coefficient should be 1.14, calculated excluding tyre code 127 which exhibits significant variation. JATMA also proposes that the abrasion index range for tyres used in the Annex 4 procedure should be set between 0.4 and 0.5, and that no restrictions should be imposed on baseline test facilities when applying the Specific Transfer Function.

This status report documents the Tyre Abrasion Task Force’s progress toward finalizing a draft UN Regulation on tyre abrasion for C1 tyres, as presented to GRBP 83 Part II. The task force pursued three workstreams: data analysis to reduce method uncertainty and inversion risk, editorial improvements to increase clarity of the draft regulation, and development of a method equivalence solution. GRBP 83 Part I achieved consensus on limit values and introductory dates but could not reach consensus on equivalence procedures between convoy and drum methods. Six informal documents (GRBP-83-32-Rev.1, GRBP-83-48-Rev.1, GRBP-83-49, GRBP-83-50-Rev.1, GRBP-83-53, and GRBP-83-55) addressing equivalence methodology, drum specifications, and code of practice frequency were submitted for potential adoption at the extraordinary GRBP 83 Part II session.

Proposal to amend document GRBP-83-32-Rev.1. Paragraph 1.2.9. amended to exclude special use Professional off-road tyres from scope. Paragraph 2.51. amended to read that the authority which has granted type approval may verify conformity control methods, with normal minimum frequency of verifications at least once every three years. Justification states special use tyres should be excluded as no limits will be established for them, and the three-year frequency aligns with Schedule 1 of the 1958 Agreement.

ETRTO comments on EC/JRC compromise proposal for Annex 4 tyre abrasion. ETRTO proposes an ALI range minimum of 0.5 as feasible and consistent with statistical distribution in MA results, rejecting the 0.7 range as unrealistic. For Generic Transfer Function gain, ETRTO recommends retaining a = 1.38 rather than the revised a = 1.45, to minimize rejection of good vehicle test results. ETRTO requests TFTA ToR amendment to confirm these conditions by February 2027 based on TA-45-9.

The document establishes procedures for demonstrating equivalence between vehicle circuit and indoor drum test facilities. It defines requirements for selecting exercise tyres and participating facilities, establishing baseline values from multiple facilities, and comparing facility results against baselines. For indoor drum facilities, transfer functions mathematically relate drum results to vehicle results, either as generic (fixed coefficient) or specific (facility-determined coefficient). Facilities must meet statistical criteria including result deviation limits and root mean square deviation thresholds to demonstrate equivalence.

ETRTO presents its position on remaining open points for C₁ tyre abrasion limit settings, reminding positions from GRBP-82-24. Key points include: inclusion of two assessment methods; limit settings proposing approximately 23% market removal by Euro7 application timeline and additional 13.5% removal five years later; exclusion of C₁ special use tyres representing 0.7% of EU market; retention of 0.1 allowance for Extra Load tyres and tyres with nominal aspect ratio 40 suitable for speeds 300 km/h representing 7.2% of market. ETRTO views this as a challenging compromise package respecting political expectations and industry effort.

Proposal to establish a list of test facilities deemed equivalent pursuant to paragraph 12.8 of the draft UN Regulation on tyre abrasion. The list recognizes six foundational facilities that participated in the initial inter-facility campaign to develop abrasion limits for C₁ tyres. The facilities are: DEKRA Test Center SA (France, circuit); IFV (Germany, circuit); Link Engineering Company GmbH (Germany, circuit); Bridgestone Corporation (Japan, indoor drum); Sumitomo Rubber Industries, LTD. (Japan, indoor drum); and The Yokohama Rubber Co., Ltd. (Japan, indoor drum). These facilities generated foundational data used to define abrasion limits and are deemed equivalent for equivalence procedures under Annex 4.

ETRTO presents a temporary conservative transfer function for tyre abrasion testing with a gain value of 1.5, designed to minimize drum inversion risk and reduce rejection risk while enabling coexistence of Indoor Drum Method and Outdoor Vehicle method at GRBP 83rd session. The transfer function, based on TA-40-2 data analysis, will be revised following a 2026 workplan before a more relevant solution in Supplement 1 to UNRxxx at GRBP 84th session.

Proposal to amend GRBP/2025/27 based on GRBP-83-32. Modifications to Annex 3 revise the abrasion index calculation methods for both vehicle test and indoor drum test methods. The abrasion margin (Amargin) is redefined in two stages accounting for evolution of measurement methods and tyre technology, with different values for normal, snow, and special use tyre categories. Amargin allowances for specific tyre groups, including severe snow conditions tyres, reinforced tyres, and tyres with nominal aspect ratio ≤40, are defined as cumulative additions to the base Amargin value.

Proposal to supersede document GRBP/2025/27 for a new UN Regulation on uniform provisions concerning the approval of tyres with regard to abrasion performance. The regulation establishes scope, definitions, application requirements, marking standards, approval procedures, and technical requirements for class C₁ tyres. It excludes temporary-use spare tyres, competition tyres, ice grip tyres, studded tyres, and certain other tyre categories. Type approval is granted if candidate tyres meet abrasion performance limits measured by one of two methods: vehicle testing on public open roads or indoor drum testing. Abrasion index limits are defined for normal, snow, and special use tyres, with adjustments for specific tyre groups. Requirements include conformity of production verification, penalties for non-conformity, and transitional provisions establishing Stage 1 and Stage 2 implementation timelines with specified dates for mandatory approval.

Proposal to ensure robust tyre abrasion measurements regardless of the test method used.

Procedure for Demonstrating Equivalence of Vehicle Test and Indoor Drum Test Facilities for Tyre Abrasion and Determining the Transfer Function for Indoor Drum Test Facilities

Guidance document on the Procedure for Demonstrating Equivalence of Vehicle Test and Indoor Drum Test Facilities for Tyre Abrasion and Determining the Transfer Function for Indoor Drum Test Facilities

Proposal for acceleration calculation based on GNSS data to amend document GRBP/2025/27.

Proposed amendments to the initial proposal

Proposal to amend ECE/TRANS/WP.29/GRBP/2025/27

Proposal for a new UN Regulation for the approval of new pneumatic tyres of class C1 that conform to UN R117 with regard to their abrasion performance.

Proposal from the GRBP task force on Tyre Abrasion to delete provisions from UN R117 that are covered by the proposal for a new UN Regulation on tyre abrasion.

Proposal for a new UN Regulation on the uniform provisions concerning the approval of tyres with regard to abrasion performance.