MECHANIC CHANGING A #1 MAIN TIRE ON A B737ER; FAILS TO NOTICE THE TWO LETTER DESIGNATOR 'ER' ON THE REMOVED TIRE; WAS A SPECIAL TYPE REQUIRED FOR THIS PARTICULAR AIRPLANE. CORRECT TIRE WAS INSTALLED APPROXIMATELY TWENTY DAYS LATER.

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BULLETIN ABOUT ACFT (737ER) WAS POSTED ON THE WEBSITE. I READ IT THE SAME DAY IT CAME OUT. I HAD NEVER CHANGED A TIRE ON THIS PARTICULAR AIRPLANE. I GOT MY WORK ASSIGNMENT ON THE NIGHT OF SEP/XA/08. I WAS WORKING OVERTIME THAT NIGHT. THE ASSIGNMENT WAS TO PERFORM A SVC CHK ON THIS PLANE (737ER). FOUND THAT #1 TIRE NEEDED TO BE REPLACED. SEVERAL MONTHS HAD PAST BY AND DID NOT REALIZE ABOUT THE BULLETIN ON THE WEBSITE. I LOOKED THROUGH THE MAINT MANUAL AND FOR SOME REASON I DID NOT COME ACROSS IT. I FINISHED MY ASSIGNMENT WITHOUT KNOWING THAT THIS PARTICULAR TIRE FOR THIS PARTICULAR PLANE HAD THE 2 LETTERS ('ER') AT THE END. I HAVE SVCED THIS PLANE IN THE PAST FOR OTHER REASONS BUT THIS WAS MY FIRST TIME CHANGING A TIRE ON THIS PARTICULAR PLANE. IT WAS BROUGHT UP TO MY ATTN ON THE NIGHT OF OCT/XA/08; THAT THIS HAD BEEN RPTED ON THE DISCREPANCY DETAILED RPT. I LOOKED IT UP ON THE WEBSITE AND READ THE RPT; NOTICING THAT THIS WAS CORRECTED BY ANOTHER MAINT MECH. TIRE WAS REPLACED ON OCT/XA/08 AT ANOTHER STATION.