skateboard wheels
I would not have known that all skateboard wheels are not the same if not for my oldest son, who is into skateboarding big time.  There are many different sizes and brands of skateboard wheels.  One website alone had over 100 different brands of skateboard wheels.  And each skater is different in their preferences for skateboard wheels.  Some skateboard wheels are made specifically for doing tricks, and some for speed and cruising.  Different skateboards require different skateboard wheels sizes.  I was surprised to find out that there are difference in hardness of some skateboard wheels, some are a bit softer which allows for a smoother ride on rough surfaces and some are harder for speed purposes.  The bearings and hardware are also different for varying skateboard wheels. There is also a lot of personal preference involved in the decision for skateboard wheels. The price of skateboard wheels depends on the size, the brand and the hardness of them.  You really need to do research if you plan to buy skateboard wheels, decks and trucks for someone with a skateboard.