Comparison of wheel wear on Curiosity's left middle and left front wheels, sols 513 and 546

Comparison of wheel wear on Curiosity's left middle and left front wheels, sols 513 and 546
Comparison of wheel wear on Curiosity's left middle and left front wheels, sols 513 and 546 Each column contains photos of one wheel. Column 1: left middle wheel, sol 513. Column 2: left middle wheel, sol 546. Column 3: left front wheel, sol 513. Column 4: left front wheel, sol 546. Images have been paired to show comparable parts of each wheel on the different sols. NASA / JPL / MSSS / Emily Lakdawalla