It’s risky business, but Knicks general manager Glen Grunwald said Tuesday the major core of the roster will be back next season as the franchise banks on Amar’e Stoudemire’s knees and J.R. Smith’s head healing.

Grunwald confirmed the Knicks are unable to do a sign-and-trade for free agents Chris Paul or Dwight Howard because of new collective bargaining agreement rules forbidding luxury taxpayers from partaking in free agency. They only have the $3.1 million mini-midlevel exception, plus the 24th overall pick in June’s draft.

That $3.1 million exception could partially be used to keep their own free agents, Chris Copeland and Pablo Prigioni. The Knicks are permitted to deal Copeland or Prigioni in a sign-and-trade, however, but can only get back a trade exception, draft pick or cash. The Knicks can then use the trade exception, worth say, $3.2 million, to acquire another player under contract at that dollar amount.

So there’s not a whole lot of big stuff for Grunwald to do other than pray Stoudemire and Smith come back repaired. And the window is closing fast.

“We’re focused on now,’’ Grunwald said. “We’re trying to get to a championship as soon as possible. That’s where our strategy is right now.’’

Smith will opt out of his contract and become a free agent July 1 and the Knicks likely will re-sign him under the early-Bird rights rule for a contract starting at $5.4 million. Smith became the goat of the playoffs, losing his shot and reputation amid Rihanna’s allegations his on-court troubles were due to being “hung over.’’

“It’s best to maintain the continuity if there’s a reason you think you can get better,’’ Grunwald said in a state-of-the-Knicks press conference at the team’s Westchester County practice facility. “I think we can get better. I think we can play better than we did in the playoffs. That’s not to say we won’t explore all our alternatives. That’s my job.

“I’m disappointed in the season but I’m not discouraged about this team. I’m very excited about the future. Obviously we’ve got some work to do. We’re not where we want to be.’’