Freestyle scooter wheels come in many diameters and widths. As a rule of thumb, beginners should stick to 100mm or 110mm wheels, while intermediate to pro riders can venture up into the 120mm and 125mm range. Standard width for scooter wheels is 24mm, although 30mm wheels are quickly gaining in popularity. Wheels also come in 26mm and 28mm widths. Wheels can be spoked, have a solid metal core, or a hollow core. Hollow cores are very popular these days due to their light weight. But weight is relative, as metal core and spoked scooter wheels weigh mere ounces more than hollow cores so pick the wheels that you think look the best on your trick scooter.
Another consideration to make when purchasing scooter wheels is brake compatibility on your scooter deck, as well as wheel compatibility of your forks. For example, if you are purchasing 120mm scooter wheels, your forks and deck brake must also be able to accomodate 120mm wheels.