BECAUSE OF WT AND BALANCE DATA ERRORS; A C208'S TAIL DRAGGED ON THE TXWY WITH THE NOSE WHEEL IN THE AIR. THE ACFT WAS REWEIGHED AFTER RETURNING TO THE GATE.

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I CHKED THE PAX IN FOR THE FLT WHILE MY COPLT CLEANED UP THE AIRPLANE FROM THE PREVIOUS FLT. MY COPLT PICKED UP THE ATIS AND GOT THE CLRNC WHILE I LOADED THE BAGS INTO CARGO BINS A AND B THEN LOADED THE PAX. AFTER THE PAX WERE SEATED; I CLOSED THE DOOR AND REMOVED THE TAIL STAND. I DID A FINAL WALKAROUND OF THE ACFT TO ENSURE THE ACFT WAS SECURE FOR FLT. I CLBED INTO THE R SEAT OF THE ACFT; AS IT WAS MY COPLT'S LEG TO FLY. I BRIEFED THE PAX AND DID THE WT AND BAL WHICH SHOWED A CTR OF GRAVITY NEAR THE AFT END OF THE ENVELOPE BUT WELL WITHIN LIMITS. WE THEN RAN THE CHKLIST AND STARTED THE ENG. WE RECEIVED OUR TAXI CLRNC AND TAXIED OUT FOR RWY XX. EVERYTHING CHKED OUT WITHOUT EVEN THE SLIGHTEST HINT AT A PROB. AS MY COPLT TAXIED EVERYTHING FELT COMPLETELY NORMAL. WE TAXIED ACROSS RWY XY AND MY COPLT APPLIED A SLIGHT BACK PRESSURE TO THE YOKE TO LESSEN THE FEEL OF THE BUMP WHEN XING THAT RWY. RIGHT AFTER XING THE RWY THE ACFT'S NOSE ROSE SLOWLY AND THE TAIL SCRAPED THE TXWY. I SAID MY AIRPLANE AND TOOK CTL OF THE ACFT. I APPLIED PWR AND TAPPED THE BRAKES AND THE NOSE CAME BACK DOWN. I THEN ASKED GND CTL TO RETURN TO THE GATE AND WE WERE GIVEN TAXI INSTRUCTIONS BACK TO THE RAMP. DURING THE TAXI BACK I HELD THE YOKE FORWARD AND NOTED THAT THE STEERING FELT NORMAL. WE SHUT THE PLANE DOWN AND ASKED THE LINE GUY TO INSTALL THE TAIL STAND. AFTER THE TAIL STAND WAS INSTALLED; WE DEPLANED THE PAX. UPON ADDITIONAL REVIEW OF THE ACFT WT AND BAL RECORDS; MY COPLT AND MYSELF FOUND THAT THE DATA WE HAD AVAILABLE AND BELIEVED TO BE THE MOST CURRENT WAS NOT UP TO DATE; THEREFORE RESULTING IN INCORRECT CALCULATIONS. ADDITIONALLY; WE FOUND THAT THE CURRENT WT AND BAL DOCUMENTS ON BOARD THE ACFT HAD ERRORS AND WERE INCORRECT. AFTER THE ERRORS WERE DISCOVERED THE COMPANY TOOK ACTION AND HAS REWEIGHED THE ACFT AND HAS CORRECTED ALL ERRORS. SUPPLEMENTAL INFO FROM ACN 793716: AS I TAXIED EVERYTHING FELT COMPLETELY NORMAL. THE AIRPLANE DID NOT FEEL TAIL HVY AT ALL. I TAXIED ACROSS RWY XY AND APPLIED A SLIGHT BACK PRESSURE TO THE YOKE TO LESSEN THE FEEL OF THE BUMP WHEN XING THAT RWY. THEN I RETURNED THE CTLS TO NEUTRAL. RIGHT AFTER THAT I GLANCED DOWN AT THE PANEL AND THEN BACK UP AND SOMETHING DIDN'T LOOK RIGHT. AT FIRST I THOUGHT THAT MAYBE MY SEAT HAD RECLINED SO I TRIED LOOKING ABOVE THE NOSE AT WHICH POINT I REALIZED THAT I COULD NOT SEE THE TXWY AND THE NOSE HAD COME OFF THE GND. I CONFIRMED THE PWR WAS IDLE AND THE CTLS NEUTRAL. WHILE I WAS DOING THIS I SAID TO THE CAPT 'WHAT IS THIS?' RIGHT AFTER I SAID THAT WE HEARD THE TAIL TIE DOWN HOOK SCRAPE THE GND.