The drive wheel with belt sprocket for the Surge fits the rear left axle and provides the skateboard's push. There is a non-removable 3M-270 belt sprocket molded on the inboard side of the 85 mm x 47 mm wheel to take the drive belt (sold separately).
Your Surge skateboard only uses a single drive wheel, and the right side rear wheel is the same freewheel as the two front wheels assemblies.