B737-700 CREW TAXIED ONTO A TXWY THAT WAS RESTR TO ACFT 50000 LBS OR LESS.

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WX: GOOD VFR AND NO FACTOR. FOLLOWING A VISUAL APCH TO RWY 8 AT LBB; THE CAPT EXITED THE RWY AT TXWY K AND THEN TURNED R ONTO TXWY H. TWR CTL NEVER SENT US TO GND CTL; SO I ASKED THEM IF THEY WANTED US ON GND FREQ. THIS CONVERSATION OCCURRED AT THE SAME TIME WE TURNED ONTO H. TWR INSTRUCTED US TO SWITCH TO GND; WHO SUBSEQUENTLY INFORMED US THAT WE WERE ON A TXWY NOT STRESSED FOR OUR ACFT AND TO EXIT AT THE FIRST AVAILABLE OPPORTUNITY. WE EXITED AT TXWY C AND TOOK TXWYS J AND R TO THE RAMP. LESSON LEARNED: REVIEW THE 10-9 PAGE MORE THOROUGHLY PRIOR TO ARR. I FAILED TO RECOGNIZE THE SMALL POSTAGE STAMP SET OF INSTRUCTIONS CONCERNING UNUSABLE TXWYS. HAD I THOROUGHLY REVIEWED THIS; I COULD HAVE ALERTED THE CAPT TO THE POTENTIAL CONFLICT PRIOR TO THE EVENT. I WILL BE MORE THOROUGH IN THE FUTURE. SUGGESTION: CONSIDER CHANGING THE POSTAGE STAMP INSTRUCTIONS TO SOMETHING MORE USER-FRIENDLY. PERHAPS CHART COMPANY COULD LABEL EACH AFFECTED TXWY TO ASSOCIATE IT WITH THE APPLICABLE INSTRUCTION (SIMILAR TO APCH PLATES). SUGGESTION: TWR CTL MAY CONSIDER TAKING A MORE PRO-ACTIVE APCH TO PREVENTING THIS MISTAKE IN THE FUTURE. TAXI INSTRUCTIONS AND FREQ CHANGES TO GND WOULD HAVE BEEN HELPFUL IN THIS CASE. THE SUCCESS OF SAFE AIR OPS IS A TEAM EFFORT.