Yellowcard lead guitarist Ryan Mendez is headed out on the road this fall, and he’s taking along a new friend that feels pretty familiar. “I just got a black Les Paul Classic Custom with beige binding, and it’s actually being set up right now,” he explains. “I retired my ’72 Custom last year. It’s such a beautiful guitar, and I don’t want to get it banged up.”

With Yellowcard’s last album selling more than 3 million records worldwide, the expectations are high for the punk-pop outfit’s new release, Paper Walls (Capitol). From Jacksonville, Florida, Yellowcard will tour behind their sixth studio album throughout the fall, and the latest addition to the Mendez arsenal will take its place alongside a Silverburst Les Paul Custom and an SG Supreme. It marks the continuation of a relationship that began long ago.

“When I was 16, I got my first real guitar, which was a black Gibson Les Paul Custom, and it was like a dream come true,” Mendez remembers. “I come from a background of liking a lot of the harder rock stuff. Growing up, a lot of the artists I listened to used Gibson: Slash, Zakk Wylde, Led Zeppelin. To me, it’s like the classic hard-rock guitar.”

Vocalist/guitarist Ryan Key, meanwhile, will be equipped with an all-black Les Paul Studio when Yellowcard’s fall dates commence in Boston on Sept. 9. (The Jacksonville, Florida, band, which spent late June and most of July on the 2007 Vans Warped tour, will first play a series of club gigs with Sum 41, followed by a 21-show run with Blue October.) Key, Yellowcard’s lyricist and frontman, says he feels fortunate to share guitar duties with the other Ryan, the band’s newest member.

“Basically, [Mendez] is really, really good, and I’m just okay,” Key says with a laugh. “He went headfirst into every record he ever loved, and he can play them from top to bottom. He’s just such a technically talented guitarist. It’s awesome to have that… It’s great because I can really work on the songs, focusing on the melody, and I know that whatever he’s going to create, it’s is really going to complement what I’m doing.”

Paper Walls, which features the band’s hard-charging brand of rock, punk, and classical, is the fifth album for Yellowcard (Key, Mendez, bassist Pete Mosely, violinist Sean Mackin, and drummer Longineu “LP” Parsons) and follows 2006’s Lights and Sounds and 2003’s multi-platinum Ocean Avenue.

These days, Key and Mendez are getting a stripped-down taste of the road ahead. They’ve been traveling from radio station to radio station, playing acoustic versions of several of the new album’s songs, including “Light Up the Sky,” the lead single and a tune Key crafted with a 2005 Gibson J-45.

“When I started playing guitar I was about 13, and the first thing I did was write my own songs,” Key says. “I never really sat down and dissected the records and learned how to play them because I was always so interested in writing my own material. So I kind of developed my own way of playing, and now I’m focused on becoming a really solid rhythm player.”

Mendez, a California native, played in a band called Staring Back before joining up with Yellowcard. And he says there’s no trouble finding space in his new band’s twin-guitar lineup, which is less about solos than riff-based creativity. “We work really well together,” Mendez says of Key, “and we click really well when it comes to writing. A lot of the music for this record was comprised of us just sitting down with guitars and coming up with riffs.”

It’s unfair to call Paper Walls a comeback album—Lights and Sounds, after all, achieved gold status—but that’s not to say it doesn’t feel like one. The previous album was surrounded by difficulties, including surgery on Key’s vocal chords. “There’s a sense that we have to get into the trenches and promote this record hard,” he says.

On all fronts, so far, so good: Paper Walls, which was released in July, debuted at No. 13 on the Billboard 200, and in November the band will support Linkin Park for four shows in Japan, including two in Tokyo before audiences of 20,000 fans.

Says Mendez: “There were a lot of complications on the last record, a lot of things going on. This time, everyone feels ready.”