8" x 3" Energy Saver Ductile Steel Wheel - 4000 Lbs. Capacity8" x 3" Energy Saver Ductile Steel Wheel The Ductile Steel wheel provides extreme weight capacity for its size. The ductile steel is graphite rich, which is stronger and more durable than even our standard semi steel wheels. With a tensile strength of 45,000 PSI, you'll be hard pressed to find a job that needs a stronger wheel. The energy saver ductile steel wheel has a slightly crowned tread making it easier to swivel and position the casters during