ALLENTOWN, Pa. - After more than 30 years as rock music's biggest bad boys, after selling more than 30 million albums, Motley Crue can see the finish line, bassist Nikki Sixx says.

"We believe that a band should bow out when they're, hopefully, at their top and when they can leave an amazing legacy of music and history," Sixx says in a call last week from Canada, where the band was two-thirds of the way through a tour.

"We don't know when it's going to be, (but) we want the last few years to be on top, and we want to go out gracefully and with a bang."

Sixx's point is that now is a good time to see Motley Crue.

"We are huge rock fans, and there are bands out there that we just are like, 'Aww, dude, why didn't you pack it in before it turned into that?'" Sixx says. "And I know I'm not alone on this. A lot of my friends, we sit around and talk about this band and that band and what that album meant to us, and it always boils down to the last few years."

Sixx says the band members, including singer Vince Neil, drummer Tommy Lee and guitarist Mick Mars, are all in their mid-50s to 62, and are all healthy.

Motley Crue certainly meets Sixx's criteria for a band that's still viable.

After a career that started with nine straight gold or platinum albums and produced rock hits "Smokin' in the Boys Room," "Girls, Girls, Girls," "Dr. Feelgood" and "Without You," the original lineup is still intact. Neil took a five-year break in the late 1990s, but he's been back for more than 15 years.

The Crue's last album, 2008's "Saints of Los Angeles," was its highest-charting in 20 years. It hit No. 4, and had a Top 5 Mainstream Rock hit with the title cut.

Sixx says the band is working on a new album, and released a single, "Sex," in July. But he declines to put a date on the album's release.

"We're working on it," he says. "It's funny, you know, doing this for over 30 years, it's always like, 'When's the album done?' And we're like, 'Well, no disrespect, but it's done when it's done.'" He says the band plans to "take most of the summer off for writing, being creative and just enjoying our lives.

"It's hard when you tour to finish music, and so I think a big part of us being off the road is going to be the ability to, you know, be in one place and to be able to write and be able to put music together. We haven't been home in the summer for years. We always tour in the summer, so we're sort of looking forward to that."

Motley Crue has taken more time on new music in recent years. "Saints of Los Angeles" is its only disc of new material in more than a dozen years, and it was released on its own label, Motley Records.

"It happens when you've been around a long time," Sixx says. "You know, you don't work for a record company, you work for yourself. When the music comes, it comes.

"You have to remember, when you're 20 years old, you don't have a family, much less, probably, a girlfriend. If you do, she's probably disposable because you're just burning through people and to be on the road, that's all you do. You live and breathe that music, that band, that lifestyle.

"And as you are around longer and longer, people had kids, they get married, they don't want to work as hard because they have other things that they do. Look at Pearl Jam. ... They've been working on a new record for a few years and they don't know when it's going to be done, but they're working on music and they're working on it at their own pace.

"It is a reality, whether it's the Rolling Stones or whoever, that it takes longer because it's not all that you do. You have other things in life, and it's personal things. So the goal is, you continue to be a musician and be creative, but you're not working for somebody else, you're working for the creativity.

"So, you know, it's all about songwriting, the quality of the songs, and then the band just goes in and does our thing. Since the very first time I remember recording with Motley Crue, it's always just been magic when we record. But it always came down to the songs. And the songs were always written and then we went in and recorded."

Among the other things Motley Crue has in the works is a movie adaptation of its debauchery-and-drug-filled 2002 band autobiography, "The Dirt - Confessions of the World's Most Notorious Rock Band." The film is rumored to be ready for release this year.

"There's only so much I can say because we're sort of legally bound to keep our mouths shut," Sixx says. "Let's just say it's moving along quite nicely."

Individual members also have their own projects. Sixx, for example, has a side band, Sixx:A.M., that has released two albums - 2011's Top 10 "This is Gonna Hurt," with its No. 1 Mainstream Rock hit "Lies of the Beautiful People" and Top 10 title track, and a soundtrack to accompany his 2007 autobiography "The Heroin Diaries" that produced the gold hit "Life is Beautiful."

Sixx:A.M. already has written the music for a new album and plans to release a single by the end of summer, Sixx says. "We actually have an abundance of music and now we're kind of lassoing it in and finishing it off," he says.

Sixx confirms a Broadway play based on "The Heroin Diaries" also is in the works - its dialogue and lyrics in the "fine-tuning" stage and "we are working with set designers, directors, producers and it's moving along quickly. In fact, it's a lot faster than I thought, and an exciting, exciting, creative thing."

Sixx also is host of two hit rock radio shows, "The Sixx Sense" and "The Side Show Countdown."

Before the end of the year, Motley Crue also has scheduled a 19-day residency at the Hard Rock Hotel in Las Vegas.

With all of that, Sixx says the end certainly won't come this year, and he won't even confirm that the upcoming album will be the last. But when the band does record its finale, it will schedule a farewell tour, then that will be it, Sixx says. He promises there will be no reunion tour later.

"This is something we've been talking about for five years, amongst ourselves," Sixx says. "And we didn't know if it was 25 years, 30 years, 40 years - we don't know. I think we might have spoke too soon, because a lot of people, that seems to be the thing that everyone wants to talk about. I promise you that when we know, we'll let everybody else know, too."

So then, until the band does, what's the secret that's kept the band together all these years?

"The band has a chemistry," Sixx says. "It is what it is. You know, you either love us or hate us. We do something, and we do what we do the very best we can do it.

"A friend of mine is in a band that broke up. He said to me, 'How do you guys do it?' And I said, 'Because we didn't break up, bonehead,'" Sixx says with a hearty laugh.

"The only way to do it is to stay together. You ask somebody who's been married for 40 years, you know. 'What's the secret?' And they say, 'We never got a divorce. We worked through our problems.'"