“Don’t ask why,” Paul Westerberg sang on the Replacements’ first record, and he apparently is thinking the same thing when it comes to his band’s first shows in 22 years.

At press time, Westerberg had yet to say a peep to the press about their three-gig reunion stint with the RiotFests, the first of which is Sunday in Toronto (followed by Chicago Sept. 15 and Denver Sept. 21). The Minneapolis group’s only other remaining original member, bassist Tommy Stinson, also didn’t say much when interviewed by Rolling Stone just after the June announcement.

“The universe seems to be trying to put us together to do our thing,” Stinson said. “It was just the timing and the aligning of the planets.”

A week ago the guys were kind enough to give their hometown newspaper the scoop on the new Replacements: drummer Josh Freese and guitarist David Minehan, both of whom toured with Westerberg in the early ’90s. Freese also played with Stinson in Guns N’ Roses and on two new Replacements tracks for a 2006 anthology.

That answered one big question. In lieu of the guys themselves talking, we thought we would try to answer some of the other unknowns.

Why now?

The “aligned planets” that Stinson referred to are: His own schedule away from GNR and solo gigs; Westerberg’s willingness, after nine years away from touring; the cool appeal of the RiotFests, and the sad circumstances that brought them together in the studio last fall. They recorded four songs that became the “Songs for Slim EP,” a benefit for their former guitarist Slim Dunlap, who replaced Tommy’s late brother Bob in the band in 1987 and suffered a severe stroke last year.

“They initially got together to help their friend, then ended up having so much fun and everything felt so good, they just decided to go for it,” said former Replacements manager Peter Jesperson, who spearheaded the ongoing “Songs for Slim” series as vice president of New West Records.

There might be a now-or-never aspect to the timing, too, said Memphis music journalist Bob Mehr, who is writing an authorized biography of the band (“Trouble Boys,” due next year on Da Capo Press).

“If the Replacements story tells you anything, it’s that life is short and unpredictable,” said Mehr, referring to Dunlap’s stroke, the passing of Bob Stinson in 1995 and the death in 2008 of Steve Foley, who played drums on the band’s final tour in 1991. “I think time and reality finally set in: Tommy’s 46 and Paul’s 53. If they’re gonna reunite, they want to go out there while they can still really deliver.”

Why this lineup?

The only other member left is original drummer Chris Mars, who quit the band around the release of the 1990 album “All Shook Down” (their last) and quit the music business a few years later to focus on painting. (His artwork adorns all of the “Songs for Slim” releases, including singles with Jakob Dylan, Lucinda Williams, Frank Black and many more).

Stinson told Rolling Stone, “We didn’t speak to Chris because we knew the answer before we even asked — he’d say ‘no.’ ” (Mars, who contributed a solo track to the “Slim” EP, did not respond to a request for comment.)

Some of the band’s close followers were surprised Westerberg and Stinson didn’t choose the Minneapolis musicians who helped them make the “Songs for Slim” recordings, drummer Peter Anderson and guitarist Kevin Bowe — but those guys apparently weren’t.

“Anyone who asks ‘why’ with Paul doesn’t get the guy at all,” said Bowe, who also toured with Westerberg in 2004 and is happy he’s performing again, period. “It would have been cool to do those shows, but I really look forward to working on some new stuff with him at some point. I don’t believe his best work is behind him.”

One of the band’s longest chroniclers, Minneapolis writer Jim Walsh, doesn’t buy criticism that two members are too few to call themselves the Replacements.

“To me, the brotherhood of the ’Mats is a far-reaching one that encompasses the original, living, and dead members, and everybody who’s ever felt like they were part of it,” said Walsh, who authored a new coffeetable book on the band coming in November (“Waxed-Up Hair and Painted Shoes”).

Why the RiotFests?

While the band has fielded reunion offers from big festivals for years, the RiotFests “embody the spirit of the band,” said Darren Hill, Westerberg’s manager. “It’s an independent festival run by a kid who’s a true music fan and isn’t only in it for the money.”

That kid, Mike Petryshyn (age 34), said he got tears in his eyes when signed the deal. He said the band was on his “doesn’t-hurt-to-ask” list since starting the festival a decade ago in Chicago. “It’s just been way too long for them not to finally do this,” he said.

Petryshyn guessed that the guys also appreciated that RiotFest is not a festival that “follows trends or worries about album cycles,” as evidenced by other timelessly cool acts on this year’s lineups such as Iggy & the Stooges, X, Blondie, Guided by Voices, Public Enemy, Mission of Burma and the Pixies.

Are they only in it for the money?

It’s hard to fault a band whose influence was bigger than its sales for wanting to cash in, but there are two reasons the boys appear less than money-hungry. For one, they would have earned bigger paychecks playing Coachella and other, corporate-backed festivals. Also, part of the RiotFest money will be donated to the “Songs for Slim” fund to help pay Dunlap’s medical bills.

Why not a hometown gig?

“Too obvious” would be the obvious answer. With hometown gigs come extra expectations and distractions, too, especially given Westerberg’s hesitancy to perform anywhere.

Ironically, they’re playing the RiotFest with the Pixies, who played their first-ever reunion gig in Minneapolis and wouldn’t play their native Boston until eight months later. Of course, there’s always the chance they’ll slip in a surprise show, but as of last week, all signs indicated otherwise.

Will they be any good?

Good question. Westerberg might need some adjustment time. Stinson, on the other hand, has been a part of the well-greased GNR machinery, and Freese is one of the most precise and versatile drummers around (he also played with Nine Inch Nails, Devo and, of late, Sublime With Rome).

Of course, the Replacements were never known for precision or “chops,” but rather a rowdy and untameable spirit that could have them winging their way through cover songs one night and nailing their own tunes the next.

Their old manager believes they will at least have that spirit at these shows.

“I think anytime is a great time for the Replacements to play again, but this time it’s for exactly the right reason,” he said, referencing the “Songs for Slim” benefit EP. “Things just really clicked.”

The engineer of their “Slim” EP, Ed Ackerson of Flowers Studio, is one of the few to have seen the guys in action. He pretty much guarantees a slam-dunk.

“The energy between Paul and Tommy has been fantastic lately,” he said, “and when the two of them get together there’s an amazing chemistry that is 100 percent real and 100 percent Replacement. There’s no question that they have the vibe in spades right now.”

Personal requests?

We’re pretty sure they’re going to play “I Will Dare” and “Bastards of Young” at these three reunion shows, but of course we expect some surprises. Personally, I think “Attitude” from their last album would fit perfectly. Here are some other not-so-obvious song requests:

Jesperson: “Busted Up,” a song from Dunlap’s solo album “The Old New Me,” which they covered for “Songs for Slim.”

Mehr: “Portland,” an unreleased track that came to light on the 1997 anthology “All for Nothing/Nothing for All.”

Sonia Grover, First Avenue booker: “Portland” or “Nowhere Is My Home,” a track from the 1985 Twin/Tone EP “Boink.”

Ackerson: “Ace of Spades,” the Motörhead hit that the boys often covered in concert.

Bill Sullivan, former Replacements road manager: “That’s When I Reach for My Revolver,” a song by Mission of Burma, who coincidentally are also playing RiotFest.