Hi,
Interesting step.
I see in your picture the rear tire is installed backwards.
They pull better facing the right way, with the tread facing ahead.
If you want to change it, and the left rear tire is backwards too, and it is the same wide width as the right one is, you only need to remove both rear wheels by removing the 5 bolts at the hubs, and changing sides with them, turning them half a turn around, then the tread will face ahead.
If the left one is installed differently, then it will need to be figured out how to change them.
The tires have to be installed on the rims facing the right ways so all the spacings work right, and the tire treads can be facing ahead.
When removing wheels and tires, put wooden wedges in at the front axle pivot, to prevent the Cub from tipping over. Cubs are heavier on the left side, and can tip over if you remove parts of the rear of them.
Below is a picture of wedges, they don't need to be made at so much of an angle. Hammer them in tight.