The members of Hanson have MmmBopped their way into manhood.

The former darlings of the tween set have grown up, and their fans have grown along with them.

"The coolest thing about music and being able to be an artist and put out albums is seeing your fans go through life with you," Zac, the youngest brother of the trio, said in a recent phone interview from Boston.

"We've always had amazingly devoted fans and we are going on a journey together," the 18-year-old said. "You see the fans in different places in their lives. They get to release their energy and go through that phase of life with you."

It's hard to believe it's been seven years since the mop top boys from Tulsa, Okla., took the pop charts by storm with their debut album, "Middle of Nowhere," which sold 8 million copies and featured the hits "Mmm Bop" and "Where's the Love?"

But they're all grown up now -- Taylor, 21, has a wife and baby traveling with them on their current tour -- and Issac,is now 23.

Their music has changed, too.

Yes, Hanson still retains the harmonies, hooks and pop sensibilities. But with their latest CD, "Underneath," the brothers are really rocking.

It took them three years and $1.5 million to make the album, on their own label, 3CG Records.

"The label, 3CG, stands for Three Car Garage," Zac explained. "We came from being a garage band and the three is representative of us."

Previously signed to Polygram, the trio decided to part with its label over "creative differences," which brought a whole new series of pressures to the table, Zac said.

"There are things you have to deal with being the CEO of your record label," he said. "You worry about different things than before. We are happy to take on the pressures, which is why we did it. We knew it was hard work. Having three guys who are passionate about what they do and carry the load helps us to be artists and businessmen. But, of course, business is only to further the art."

Admittedly, all that togetherness -- musically and corporately -- can sometimes be a challenge, he said.

"Everybody fights, but this isn't an Oasis," he said referring to the British band infamous for its fights between brothers. "There are natural arguments, clashes in personalities and genetic makeup. But honestly, we get along pretty well. We have a mutual respect for each other and we're reasonable. We're men, not boys, and we know how to get over it."

This is actually the second phase of the tour in support of "Underneath."

Phase one was an acoustic tour that took the Hansons to clubs around the country and ended at New York City's Carnegie Hall.

"It is the most amazing venue in the world," Zac marveled. "For most artists, it's on that 'list of things I'll never do.'"

This time, however, the tour is "fully electric," he said. "I guess it's a rock show."

And still true to form, they're selling out across the country.

Their recent show in Chicago sold out in 10 minutes flat, Details magazine said.

The Hanson tour rolls into Kalamazoo's State Theatre on Wednesday.

They'll keep going through the summer, take a break, then rev it back up again, with dates in South America, Zac said.

It may sound tiring for some, but Zac says they're just doing what they love. And as long as they can keep doing it together, Hanson will go on.

"We've spent our whole life together," he said. "We've been singing together for 12 years and we've been brothers for longer than that."