Autosport is reporting GT300 4 tire change mandatory rule explanation.
https://www.as-web.jp/supergt/605986?all
Since multiple teams took the fuel only pit stop strategy in the first round, tire troubles occurred multitime due to extremely low tire internal pressure.
Seeing these situation, Chairman Bandoh seems to have proposed to the team and tire manufacturers the obligation to replace four tires.
The proposal reason is to eliminate tire trouble and give priority to safety.
This proposal was decided after getting the approval of the participants after going through the proper processes such as entrants and manufacturers.
The bulletin this time is only for the second round, and after the third round, it will be decided after a meeting again.