Here I am in New York, waiting to meet the city’s most fashionable street art duo, when a nice young man carrying a toddler turns up. It’s hard not to be disappointed. I wanted grit. I wanted danger. Instead I meet two personable 32-year-olds with college degrees.

Patrick Miller and Patrick McNeil met as teenagers in Arizona, but they teamed up in 1999 and have become known as Faile – pronounced “fail”, an anagram of an earlier name, ALife. They began by emblazoning their 1950s-styled pulp imagery on city streets, and have graduated to making a living putting it on everything from canvases to clothing.

Next week, however, they are getting back to their roots, joining street art crews such as Blu from Bologna, Nunca and Os Gemeos from São Paulo, and Sixeart from Barcelona (but not Banksy from London, who was not invited), in a survey of street art that will go up on the outside walls of Tate Modern. It’s not the first time the pair’s work has been exhibited in the UK – in 2006 their work played a central part in Spank the Monkey, a major exhibition of street art at the Baltic Centre for Contemporary Art in Newcastle.

Miller and McNeil painted their contribution – a splashy collision of typeface and figuration – in fragments in their New York studio, and then came to London to paste up the parts into a design almost 60ft high and 40ft wide (18m by 12m). It’s as if several layers of posters have been shredded by happy accident, and it mines a theme the pair plan to explore this autumn in a show at Lazarides Gallery in London: a prophetic dream of a tribe of Native Americans returning to reclaim their Manhattan home.

I sought out Faile because New York graffiti is the stuff of legend. At least, it was: a messenger boy calling himself TAKI 183 is credited with launching the craze in the early 1970s, and later, when the city was fighting crime and recession, the scene exploded in the city’s subway. Keith Haring and Jean-Michel Basquiat brought it into the galleries in the 1980s. Then a succession of New York mayors cracked down.

Miller recalls the era as graffiti’s boom time. “The city has become so gentrified in the past 15 years that it’s pushed a lot of that out.”

The pair admit that they were clueless about the etiquette of graffiti when they began. “We never had any links to the culture,” says McNeil. “Certainly not until we moved to New York and started putting our stuff on top of it. And then people said, ‘Hey man, don’t do that, that’s someone’s work, and if they find you they’re going to mess you up.’ ” Faile see their roots in street art rather than graffiti. “Street art is the expansion of graffiti,” McNeil says. “Graffiti is an inside language. It’s relevant to the crew that do it. Street art connects with the masses.”

Comparing Faile’s work with normal graffiti, it’s clear that they are very different. That makes Faile typical of a new generation of artists who are finding livelihoods at a point where the street, the gallery and the worlds of advertising and fashion meet. McNeil and Miller have degrees in graphic design, and their work is informed by the history of art. There are flashes of radical politics but you’ll also find slick marketing on their website, which presents their work in the style of the Yellow Pages.

But does Faile’s work really belong in a gallery, or even, as at Tate Modern, on its exterior walls? “That’s tough,” Miller says. “We were making these kinds of things on the street, and then all of a sudden the fine art world decided to embrace it. It’s not as if we’ve closed the door on the street.”

Street Art at Tate Modern, London SW1 (www.tate.org.uk 020-7887 8008), May 23-Aug 25; Faile feature in The Outsiders, Lazarides Charing Cross, London WC2 (www.lazinc.com 020-7287 1779), from May 23. For more information, see www.faile.net

Editor's choice

• The 100 Best Films of the Decade
• 70 facts you didn't know about Marvel
• The 50 Biggest Movies Of 2010