Kourt and Travis got on the road Thursday to head to Indio, California for the huge Musical Festival weekend ... and she made sure to flick it up and show support for her hubby ahead of his set.

While on the road, she posted a few photos from inside the trailer using the Coachella geotag, showing off her 'fit and giving fans a sneak peek behind-the-scenes.

Of course, she couldn't help but promote Poosh's party, which is an 'adult sleepaway camp' held during the festival weekend.

Kourt's looking like the ultimate rockstar groupie -- shades paired with a graphic tee and black leather jacket.

Most importantly, she posted a shot of Trav's practice drum kit, referencing the hot topic for all Blink fans -- how's he gonna play with his injured hand?!?

As we reported, Travis had surgery to repair his busted left ring finger a little over a month ago ... and that forced the band to postpone dates on their first tour together in 9 years.

Everyone was shocked when the pop-punk rockers were a last-minute addition to Coachella's Friday night lineup. As you can see, frontman Mark Hoppus is amped for their set inside the Sahara tent.

The band formed back in 1992 ... and over 3 decades later, fans are still lining up to see 'em rock out.