Custom wheel on aluminum rim with steel hub and spokes. 12 x 1.75 pneumatic tires. If the rider is a little older and stronger and can handle the added weight of the pneumatic system (and youre willing to maintain proper tire inflation!) this wheel set offers a great ride characteristic and excellent traction. For beginning riders or really young/lightweight riders, we still recommend the standard EVA polymer wheel set due to its light weight. Each pneumatic wheel weighs about 1 POUND more than the EVA polymer wheel set.