C172 STUDENT PLT LANDS ON THE WRONG RWY CAUSING AN ACR TO GO AROUND AT TUS.

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I WAS PIC FOR A C172M ON RETURN TO TUS ARPT FROM FIRST SOLO XCOUNTRY FLT. I DEPARTED FROM TUS 2 HRS PRIOR BUT WIND DIRECTION HAD CHANGED SINCE MY DEP FOR XCOUNTRY FLT. I TOOK OFF ON RWY 11R; BUT RWY 29 WAS THE ACTIVE UPON MY RETURN WHERE THE SITUATION OCCURRED. I FLEW A R-HAND TFC PATTERN FOR RWY 29 AT 3400 FT. TWR CLRED ME TO LAND ON RWY 29L BUT I MISINTERPED AND THOUGHT I WAS CLRED FOR RWY 29R. ON FINAL OVER RWY 29R TWR VERIFIED THAT I WAS ON RWY 29R AND INITIATED AN ACR FOR A GAR. THE ACR WAS ABOVE AND BEHIND ME FOR RWY 29R AT THE TIME OF THE INCIDENT. THE ACR FLEW A GAR ABOVE ME ON RWY 29R AT ABOUT 500 FT ABOVE ME. IN MY OPINION SOME POSSIBLE CONTRIBUTING FACTORS WERE MY UNFAMILIARITY WITH RWY 29R AND RWY 29L TFC PATTERN. I WAS A STUDENT PLT RETURNING FROM MY FIRST SOLO XCOUNTRY FLT FLYING THE RWY 29R AND 29L PATTERN FOR THE FIRST TIME. IN ADDITION; MY PERCEPTION THAT I WAS CLR TO LAND ON RWY 29R WAS WRONG. TWR CLRED ME TO LAND ON RWY 29L AND NOT RWY 29R. HOWEVER; FROM WHAT I CAN RECALL; TWR HAD CLRED ME FOR RWY 29R AT AN EARLIER POINT BUT CHANGED TO RWY 29L. I HEARD ALL THE INSTRUCTIONS FROM TWR LOUD AND CLR BUT SOMEHOW THOUGHT I WAS CLR TO LAND ON RWY 29R.