Urethane is a chemical group composed of five specific atoms set in a certain order. Polyurethane is a material that incorporates many urethane groups to help create materials that are stronger than their base components. Urethane has some unique properties that make it perfect for wheels. It has good abrasion resistance, good grip and traction with the ground, and a high resiliency or rebound. This means that urethane wheels, even without a pneumatic tube, are still fast. Homemade urethane wheels involve the use of specialised chemicals and machinery.
Combine the urethane chemical groups into a metering machine that heats and mixes them into polyurethane.
Mix dye or your choice of pigment into the liquid polyurethane if you want your wheels to have colour or tint.
Distribute polyurethane into aluminium moulds similar in shape and size to what you would like the finished product to be.
Transfer the slug or unfinished wheel from the mould after the polyurethane has solidified onto a flat surface.
Cut the slug into shape by hand on a lathe machine. The lathe turns the slug as it shapes it, cutting away the extra polyurethane.
Set lathe machine to cut the sides and riding surface of the wheels to match each other exactly.
Urethane wheels vary in colour, shape, diameter and durometer. Soft wheels that have a low durometer are good for cruising on hard surfaces. Hard wheels have a higher durometer and are able to absorb little shock.
Adding colour may actually weaken the wheels. Urethane is normally a whitish clear colour. Dyes or pigments take up room in the structure of the wheel, which means less resilient urethane. Some believe dye alter the chemical structure. If you are looking for high performance wheels, clear wheels are recommended.