"GRRR!", Is the latest The Rolling Stones' multi-disc best-of compilation celebrating the band's 50th anniversary and it features literally dozens of classic songs that span the British rockers' entire career, as well as two newly recorded tracks, "Doom and Gloom" and "One More Shot."

In a recent interview with Billboard, singer Mick Jagger and guitarist Keith Richards discussed the new tunes and the band's forthcoming tour plans, among other topics. Richards reveals that the decision to include new material on GRRR! came about "at the last moment," explaining the label told Jagger and him "it'd be nice to have an extra track or two."

Keith notes that he and Mick happened to each have a new tune about ready to go.  He adds, "It was probably the quickest Rolling Stones recording sessions that I can remember, ever.  We cut two tracks in three days, boom."

Jagger, meanwhile, says he quickly put together a demo of "Doom & Gloom," and the finished version didn't stray far from his original recording. "Everyone's saying good things about it, so I can't be happier," he offers.  He also gives props to "One More Shot," which he says was written mostly by Richards, with "some extra lyrics" contributed by himself.

As for the upcoming tour dates, Richards reports that, at drummer Charlie Watts' behest, The Stones will be performing with a stripped-down lineup.  He explains, "We'll have [longtime touring saxophonist] Bobby Keys in for a few horn things but we're not carrying sections."  He admits that playing in that type of configuration puts more pressure on the guitarists, but insists he's up to the challenge.

Keith declares, "OK, you want the blues band, you want the rock 'n' roll, stripped down?  You're going to get it.  It's going to be fun, man."

So far, The Stones have only confirmed five 2012 dates, two in London, two in Newark, New Jersey, and one in Brooklyn, New York.  However, both Jagger and Richards imply that there will be more to come next year.

Asked if the band will be keeping its options open for 2013, Jagger says, "I suppose you could say, yeah."

Richards adds, "This juggernaut, once it gets rolling, is almost unstoppable…Right now, I'm just happy to have the thing rolling and moving.  It'll be great, playing London and New York.  The rest of it, it'll happen.  Don't worry about it."