ATCT CONTINUED USING DOWNWIND RWY FOR OPERATION EVEN THOUGH TAILWIND EXCEEDED MAXIMUM TAIL WIND COMPONENT FOR ACR ACFT.

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ATIS AT LAX RPTED 12 DEGS C; WIND 100/08 FOR RWY 25R. WE WERE JUST LEGAL FOR TKOF AT 350000#; FLAP 8/16 AND BLEEDS CLOSED ON THE WDB WITH OUR CHARTS; ALONG WITH TKOF CLRNC TWR. RPTED WIND AT 100 DEGS; 12 KTS OUR PRECOMPUTED DATA FOR TKOF WAS NO GOOD AND THIS EXCEEDED OUR 10 KT TAILWIND LIMIT FOR THE WDB. WE REQUESTED RWY 7 AND WERE TOLD TO EXPECT 20-30 MIN DELAY. AT THE END OF RWY 7 WE WAITED 25 MIN WHILE THERE WE OBSERVED WINDS ON WINDSOCK OF 090-100 DEGS/15 KTS. TWR NEVER RPTED WIND OVER 11 KTS EXCEPT FOR OUR TKOF CLRNC ON RWY 25. OTHER FLTS LNDG AND DEPARTING QUESTIONED THE RWY SELECTION BUT DID NOT REQUEST RWY 7 AS WE DID. THE IMPASSE WAS RESOLVED WITH WIND SHIFT TO 200-220 AT 7 KTS. WE TAXIED BACK TO RWY 25R AND DEPARTED W/O INCIDENT. WE WOULD HAVE SAT FOR RWY 7 UNTIL FLAMEOUT DUE TO LAX ATC USING A DOWNWIND DEP PROC EXCEEDING ACFT LIMITS. WE FEEL THE TWR LIED ABOUT THE WIND BASED ON OUR OBSERVATIONS AND THEY WOULD NOT ALTER THEIR PROCS WHEN CHALLENGED. IT IS A SHAME OTHER PLTS WOULD NOT CHALLENGE LAX TWR AND FORCE A RWY CHANGE.