Tony Hawk -- New Hoverboard Video's NO HOAX ... Cross My Heart

Tony Hawk swears his new hoverboard video is 100% REAL. No joke. No hoax. No fakies.

There was serious speculation about the footage ... since the last time we saw Tony riding a "Back to the Future" inspired board ... the whole thing turned out to be one giant prank. It sucked.

But Hawk appeared on "TMZ Hollywood Sports" on Reelz this week and set the record straight -- telling us it's totally legit ... and spilled his guts about the 15 sessions he spent riding an actual, functional hoverboard at a special warehouse in Santa Clarita, CA.

Hawk says the board weighs about 90 pounds ... and runs around $10k-per-unit.

Tony just posted more footage of his ride on his new website TheRideChannel.com showing all sorts of tricks, spins and even some falls. Pretty cool stuff.

BONUS: Hawk also talks about the NEW TONY HAWK VIDEO GAME coming out next year ... so get your thumbs ready.