How many different sizes of truck wheels are there?

There are a wide variety of truck wheels. There are wheels for small pick-up trucks, military trucks, and "big rig" trucks. There are over 7 standard truck sizes for tires. Cooper Tire lists over 20 different sizes for truck tires. Another website lists over 100 truck tire sizes. Each tire fits on a certain type of wheel. There are hundreds of different wheel types and sizes.