Van Halen Postpone Tour -- We're Just Burned Out

Even rockstars can get tired ... and TMZ has learned that's exactly why Van Halen decided to postpone 31 upcoming concert dates.

Sources close to the band tell us ... the guys felt like the current schedule was "too much, too fast" ... and they were "losing their focus."

One source tells us, "They're simply burned out" ... adding, "They want to make sure their concerts are not a routine ... they want every performance to be special."

We're told the guys want to take some time to "re-charge their engines" ... so they can rock all 31 cities the way Van Halen fans expect to be rocked.