These Service Caster Series #30 Thermoplastic Rubber Flat Tread on Polyolefin Core casters offer various wheel sizes and mounting heights: 4” wheel: 5-5/8” mounting height; 5” wheel: 6-1/2” mounting height; 6” wheel: 7-1/4” mounting height; 8” wheel: 9-1/2” mounting height. Weight Capacity: 4": 300 lbs Capacity/Caster, 5": 350 lbs Capacity/Caster, 6": 500 lbs. Capacity/Caster, and 8": 600 lbs Capacity/Caster Top plate measures at 4" x 4-1/2" with a bolt hole pattern of 2-5/8" x 3-5/8" to 3" x 3" and can either be bolted or welded on. HARDWARE NOT INCLUDED Find other wheel materials, sizes and all Service Caster products at our Amazon Storefront. Click on the “by Service Caster” link above the main title on any Service Caster page listing. High quality replacement caster for McMaster Carr caster 30305T58. Listing is for one (1) Service Caster Series #30 swivel caster with a 6" diameter, 2" wide thermoplastic rubber tread on polyolefin core wheel. Supports 500 pounds (lbs) per caster. When searching for a reliable and durable solution to your McMaster Carr replacement caster needs, consider Service Caster’s Series 30 top plate thermoplastic rubber flat tread on polyolefin core casters. The soft flat tread is made of thermoplastic rubber that is non-marking and non-marring, and on the polyolefin core provides a long lasting, high capacity wheel that is capable of easy rolling under heavy loads. Finely crafted with double ball bearing heat treated raceways, these versatile casters are ideal for a wide range of applications, such as dollies, platform trucks, warehouse carts and freight terminals. Or ensure a smooth and secure ride for food service carts, hotel housekeeping carts, and industrial and commercial equipment. Even drywall carts, welding carts, and wall panel carts will be ready to roll on the Series 30, keeping you moving forward. Service Caster is unsurpassed in quality, reliability, and excellent customer service. Count on us to move you forward.