It depends on which hot wheels car that you have.
rubber
To make a car that has wheels made out of compact discs, everything else must be in porportion.
the wheel is made of rubber
Traxxas summt
Casting Casting
Carbon...
In China
Standard car and truck wheels are made of steel, "alloy" wheels are made of a lightweight aluminum alloy.
Aluminum
A car rolls by using it's wheels.
Car wheels are made of pressed steel or molded aluminum-magnesium alloy. Most other land vehicles use steel wheels of some sort.