When two bands co-headline a national tour, a rivalry for the audience’s attention sometimes develops. Not so, according to Switchfoot guitarist Jerome Fontamillas, during the “Finding Summer” tour with Lifehouse.

“The competition isn’t who’s the best band on stage. It’s who’s the nicest band backstage,” Fontamillas jokes. “Lifehouse are literally the nicest guys on tour. We thought we were. Every night they’ve got us beat.”

It’s that affable nature, backed by a rabid following, that has kept Switchfoot going strong for more than 20 years, following their breakout record “The Beautiful Letdown” in 2003 and continuing with last year’s release of their 10th studio album, “When The Light Shines Through.”

Fontamillas sat down with amNewYork to talk about the tour and more.

You’re currently co-headlining a national tour with Lifehouse. What feels different about touring with another band?

We’ve only done one or two shows with Lifehouse throughout our whole lifetime, so it’s been a really cool experience to finally tour together. Brings a whole different group of people. So you get to play in front of people that haven’t really heard of you. But it’s like a nostalgic tour. A lot of the songs people know are songs we played years ago.

“The Beautiful Letdown” producer John Fields coproduced your latest record. What’s it like to work with him 20 years later?

He has a really good ear for music. He comes up with parts you would never guess. When we first started working with him, we were just newbies. All the stuff that he did, we were just awe-struck. So it’s a cool progression to see the growth we’ve had.

What’s your most memorable concert highlight?

One of the biggest ones, to me, was when we were playing under the St. Louis arch on July Fourth in front of 100,000 people. It was the most we’ve ever played and there were fireworks after that coincided with one of our songs. I feel like it was a dream, but it actually happened. “The Beautiful Letdown” was just getting started. It was before the social media blitz. It’s in your memory. It might have been a letdown if someone recorded it. It might not [have been] as big as you think it was.