B767 PLT IS CONCERNED WITH ATC SPD ASSIGNMENTS DURING VISUAL SIDE-BY-SIDE OPS AT SFO.

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TFC AT 12 O'CLOCK POS; ON BASE LEG FOR RWY 28R WAS POINTED OUT TO US BY APCH. WE CONFIRMED LIGHTS AT 12 O'CLOCK POS AND WERE CLRED FOR THE VISUAL TO RWY 28L. OUR INSTRUCTIONS WERE TO MAINTAIN 180 KTS TO THE BRIDGE AND NOT TO OVERTAKE THE TFC FOR RWY 28R. WE ACKNOWLEDGED. AT THE BRIDGE; WE IMMEDIATELY STARTED SLOWING. IN THE B767; YOU CAN'T TAKE FINAL FLAPS UNTIL 170 KTS AND I USED FULL SPD BRAKES TO SLOW AS QUICKLY AS POSSIBLE. DURING THIS TIME; WE WERE ADVISED BY APCH THAT WE WERE 50 KTS FASTER THAN THE TFC FOR THE RIGHT! WE REPLIED WE WERE SLOWING. WE TOOK FLAPS 30 DEGS AND I USED FULL SPD BRAKES TO SLOW TO OUR REF SPD (WITHOUT ADDITIVES) OF 138 KTS AND THEN ARMED THE SPD BRAKES FOR LNDG. AT THIS MINIMUM SPD; WE WERE STILL GAINING ON THE TFC FOR RWY 28R; AN AIRBUS. WE SWITCHED TO TWR AND WERE CLRED TO LAND ON RWY 28L. I ASKED THE FO TO ADVISE TWR WE WERE AT MINIMUM SPD AND GAINING ON THE TFC WHICH SEEMED VERY SLOW. THE FO; WHO FOR A LARGE PART OF HIS CAREER HAS FLOWN INTO SFO SAID -- DON'T WORRY; THE TWR WILL TELL YOU IF HE NEEDS YOU TO GO AROUND. I DIDN'T DEMAND HE CALL AS I WAS ABOUT TO LAND AND ALSO THINKING THROUGH THE GAR. WE LANDED PRETTY MUCH SIMULTANEOUSLY AS FAR AS I COULD DISCERN. THE LNDG ITSELF WAS UNEVENTFUL. I BELIEVE THE SIT AROSE WHEN THE TFC FLOW SEEMED TO REQUIRE A HVY ACFT TO MAINTAIN 180 KTS UNTIL A LITTLE OVER 5 MI OUT; WHILE A MUCH SMALLER AIRBUS AT MUCH LOWER AIRSPD WAS GOING TO RWY 28R. FROM NOW ON; WHEN THIS SIT ARISES; I WILL QUERY APCH ON THE GND SPD OF THE LEADING ACFT TO CHK ON THE 180 KT REQUIREMENT AT THE BRIDGE. HOPEFULLY CTLR WILL ALSO BE AWARE OF THE DIFFERENCES IN MINIMUM SPDS AMONG 'HEAVIES' AND OTHER JETLINERS.