2. Luis Sanchez, National Sales Manager for the company that makes Pro Comp wheels, shows us the beginnings of every forged Pro Comp wheel. These T6061 aircraft-quality aluminum "logs" range in length from 20 to 24 feet and vary from 6 to 10 inches in diameter. The larger-diameter logs are used to make larger-diameter wheels. For instance, a 10-inch-diameter log is used to make a 20-inch wheel. Each log comes from the manufacturer with a spec sheet that details the alloy elements that were used in the "recipe" to make that alloy log.