The 54 mm wheels from Shark Wheel Jaws are by far the wheels we install most often on entry-level skateboards, especially for children. Because they minimize the risk of falling, because thanks to the strange, innovative profile of the Shark wheels, you can get over stones and hard edges much better.
With a larger diameter (60mm, 72mm etc.) you can get over everything better, but they are more expensive and heavier, and you usually have to build "riser pads" (spacer plates) between the axles and the deck (wooden board) to prevent "wheel bites" (when the roller touches the board in a curve due to an inclined position, which leads to emergency braking, especially with soft rollers)
All Shark Wheel purchases come in a set of 4 wheels
You can find out more about all the advantages of the new, future-oriented shape via the crowdfunding project.