CVG CTLR EXPRESSED CONCERN REGARDING RWY USAGE REF TAIL WIND COMPONENTS.

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I WAS WORKING IN THE CTL TWR FOR MY WHOLE SHIFT. WHEN I GOT IN; THE FORECAST WAS FOR WINDS VARIABLE AT 4 KTS UNTIL XA00 WHEN THE WINDS WOULD BE VARIABLE AT 2 KTS UNTIL XE00 THE FOLLOWING DAY. WINDS WERE CONSISTENTLY FROM 340-010 DEGS AT 4-12 KTS. I WAS WORKING THE CAB COORDINATOR POS AT ABOUT XU00 AND HAD ENOUGH. I CALLED NWS IN ILN AND ASKED FOR AN UPDATED FORECAST. HE READ ME THE TAF; AND I ADVISED HIM WE WERE SHOWING 350 DEGS AT 9 KTS; SUSTAINED FOR THE LAST 15 MINS. HE SAID HE WOULD LOOK AT IT AND POSSIBLY AMEND THE FORECAST. SHORTLY AFTER THAT; THE FORECAST WAS CHANGED TO SHOW 290 DEGS AT 7 KTS UNTIL XA00; THEN DYING BACK DOWN. BOTH WINDS FORECASTS FAVORS A 'S FLOW' (LAND RWY 18L; 18C; 18R). BUT; THROUGHOUT THE AFTERNOON AND EVENING; WE WERE 340-010 DEGS AT 9-12 KTS. AT XI30; ACFT X (AN E170) REFUSED TO LAND AND WENT AROUND ON RWY 18L DUE TO WINDS (WHICH WERE 350 DEGS AT 11 KTS WHEN HE WAS SHORT FINAL). WE RAN THE ACFT A FEW MI S AND TURNED HIM IN RWY 36C. THERE ARE 2 PROBS. FIRST; THE CONTINUING PROB ABOUT POOR FORECASTING FROM THE NWS. MY WHOLE WORK WK; THE WINDS FORECASTS WERE CLOSE; BUT NEVER ON. WE WERE CONSISTENTLY 20-30 DEGS OFF AND EXCEEDING THE FORECASTED WINDS BY 5 KTS ALL WK. I'VE DOCUMENTED THIS PROB TO ASRS BEFORE. SECONDLY; THE MENTALITY OF CVG MGRS TO STAY LNDG S WITH LARGE TAILWINDS. OCCASIONALLY IT SEEMS OUR MGRS THINK THE WORLD WILL END IF WE CHANGE TO LAND RWY 36L; 36C; AND 36R WHEN THE WIND IS STRONG NW OR N. OUR 'WIND CHART' SHOWS A 7 KT TRUE TAILWIND IS THE MAX ALLOWED WHEN LNDG S (LARGER QUARTERING TAILWINDS ALLOWED). THROUGH AT LEAST 2 INBOUND PUSHES WE LANDED WITH WINDS EXCEEDING THE ALLOWED TAILWIND COMPONENT (ABOUT 100-130 AIRPLANES). WE ADVISED THE TRACON SEVERAL TIMES ABOUT THE WINDS; AND THEY DIDN'T ENDORSE TURNING INTO THE WIND UNTIL ABOUT XX00. LAST NIGHT'S SITUATION WAS UNSAFE. FORECASTING MUST IMPROVE. WE NEED TO GET OUT OF THE MENTALITY THAT WE MUST LAND S. IF THE WIND DICTATES WE LAND TO THE N; WE SHOULD CHANGE CONFIGNS BEFORE SOMEONE DOES SLIDE OFF THE END OF THE RWY.