Isaiah Hartenstein’s Iron Man streak is over.

The Knicks’ center was ruled out of Tuesday’s game against the Nets with an inflamed and sore Achilles, an injury that has bothered Hartenstein since at least last season.

The 25-year-old had played in 164 straight games, including Saturday when he aggravated the injury against the Raptors.

Jericho Sims, used sparingly this season, started in his place at Barclays Center.

“He’s dealt with it a while,” coach Tom Thibodeau said about Hartenstein’s injury, which the Knicks are labeling “day-to-day.”

Asked if it’s a concern, Thibodeau responded, “Everything is a concern.”

Sims, meanwhile, hasn’t logged meaningful time since suffering a badly sprained ankle on Dec. 18.

He had started five straight games until that point but lost his rotation spot because of Hartenstein’s surge and the acquisition of Precious Achiuwa, who became — and remains — the backup center.

The lineup struggled this season with Sims as the starter, but Thibodeau pointed to the team’s overall record with him in that spot before Tuesday — 3-2 — and that was also before the lineup became more balanced because of the OG Anunoby acquisition trade.

“I’m kind of used to it by now,” Sims said Monday about waiting his turn. “Every day I’m going through my same routine as if I was to play and I think that’s in the past so I will just stick with that.”

Hartenstein managed Achilles pain for much of last season but never missed a game.

With his Achilles health in mind, Hartenstein told The Post that he turned down an opportunity to play in the summer for Germany at the FIBA World Cup.

“It wasn’t like I’m hurt, it’s that I wanted to make sure I’m fully healthy going into next season,” Hartenstein said at the beginning of this campaign.