Tremain has a deal in place to join Rahal Letterman Lanigan Racing in the US, prompting his departure from Erebus after nine years.

His new role was set to start in January, however the Stateside move has been moved back a year, with Tremain instead relocating to his native New Zealand to spent time with his father as he battles serious illness.

As it stands, the plan is to start full-time with RLL in 2026, while for 2025 Tremain will be based in New Zealand and make sporadic appearances at Supercars events for Erebus.

As for the full-time Erebus structure, CEO Barry Ryan will step back into the team principal role, with Brad Packham promoted to team manager and Kieron Woodger moving into Packham’s former role of chief mechanic.

Ryan confirmed Tremain’s departure on the KTM Summer Grill.

“He’s been working on a visa all year and getting a job,” Ryan explained.

“His journey is going to IndyCar next year to work. At the moment his dad’s fallen ill in New Zealand, so best of wishes to Brad and his father and family.

“I just want to say thanks to Brad for nine awesome years. Starting as a mechanic, fresh from New Zealand, never worked on a Supercar, to being a team principal this year and leading a championship and winning two Bathursts with us. So thanks, Brad.”

The opportunity for Tremain to join RLL came after a trip to the States in the middle part of the year.

“I went over after Tasmania this year to a weekend with the team,” he told Speedcafe.

“I did the weekend with them and they were quite happy. So I have a contract with them to start in January, but that’s not happening.

“I talked to them about it and they are more than happy and understand what’s going on, and they said when I’m ready to tell them, and there will be a role ready for me.

“I’ve more or less committed to staying in New Zealand next year, to be with my family. I’d like to go across for the Indy 500 next year, but the goal right now is to be over there for the start of the 2026 season.”

As for his involvement with Erebus next year, Tremain said: “Baz wants me to do Taupo, and there’s a few others I’ll do like Townsville and I want to do Bathurst. So I’ll do a little bit here and there.”

Tremain joined Erebus in 2016 as a mechanic and rose through the ranks to be named team principal on the eve of the 2024 season.

“It has been incredible,” he said. “I didn’t really know what to expect when I moved over at the start of 2016, I planned to just go with the flow and see what it was like.

“I’m very thankful to [co-owners] Betty [Klimenko] and Barry for giving me the opportunities over the last nine years to prove my worth. I think it was a risk putting me in the roles that I went in, but for the most part it worked out well.”