High-Capacity Mold-On Rubber Wheels support heavier loads than standard mold-on rubber wheels. Long service with true abrasion resistance. 90 Durometer hard rubber tread vulcanized to semi-steel center. Require less effort to start and keep rolling. Hard tread reduces heat build up.High-Capacity Mold-On Rubber Wheels are not available online, call a Certified Product Specialists to order.