5" x 2" Mold-On Rubber Aluminum Wheel Rigid Caster - 500 lbs. Capacity5" x 2" Mold On Rubber Aluminum Wheel Rigid Caster The mold on rubber aluminum wheel is a lightweight alternative to the traditional cast iron core, providing the same load capacity with a cushioned tread and an attractive look. Tread: Rubber, Vulcanized To Core Core: Aluminum Bearing: Roller Bearing Rig: Zinc Plated Rigid Caster, 4" x 4 1 2" Mounting Plate Capacity: 500 Lbs. Color: Black and Silver Durometer: Shore A 80 (+ 5) Temperature Range: 40 F