10" x 3" Ultra Poly on Cast Wheel - 4000 lbs. Capacity10" x 3" Ultra Poly on Cast Wheel The Ultra Poly wheel is a higher capacity alternate to our standard Polyon Cast wheels. Boasting a 3 4" thick, non marking polyurethane tread and stronger cast iron core, this wheel provides a longer life under very heavy loads. Tread: 3 4" Thick Polyurethane Elastomer, Non Marking Core: Heavy Duty Cast Iron Core Bearing: Multiple Bearing Options Capacity: 4,000 Lbs. Color: Green and Black Durometer: Shore D 60 (+ 5)