Major tire makers win California approval to continue 6PPD alternative research

Washington DC – A preliminary study by 32 major tire makers into alternatives for tire anti-degradant substance 6PPD has been approved by the state of California, clearing the way for ‘stage 2’ of the research.

Coordinated by the US Tire Manufacturers Association (USTMA), the consortium received a notice of compliance form the California Department of Toxic Substances Control (DTSC) on 26 Aug for the “revised” stage 1 ‘alternatives analysis report.’

The notice will allow the consortium to formally launch development of a stage 2 report to further investigate the most promising potential replacements for the use of 6PPD in tires, USTMA said.

The consortium first submitted its preliminary report in March, which investigated over 60 initial candidates for a suitable alternative to 6PPD in tires.

The teams worked closely with regulators to update and submit a revised stage 1 report in July, following a notice of deficiency issued by California DTSC. (ERJ report)

The revised stage 1 report identified seven potential 6PPD alternatives warranting further investigation in the stage 2 alternatives analysis.

USTMA said it is optimistic that, by the end of the process, the partners will have identified “one or more” possible 6PPD alternatives with potential to replace or materially reduce the level of 6PPD in tires.

The consortium’s stage 2 report is due to DTSC on 19 Aug 2026, with an annual progress report due on 19 Aug 2025.