These Service Caster Series #30 Polyurethane on Aluminum casters offer various wheel sizes and mounting heights: 4” wheel: 5-5/8” mounting height; 5” wheel: 6-1/2” mounting height; 6” wheel: 7-1/2” mounting height; 8” wheel: 9-1/2” mounting height. Weight Capacity: 4": 700 lbs Capacity/Caster, 5": 900 lbs Capacity/Caster, 6": 1200 lbs. Capacity/Caster, and 8": 1250 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. Brake options include a top lock brake (TLB) and a total lock brake (TTL). The top lock brake (TLB) places a positive locking force against the wheel tread locking the wheel only. The total lock brake (TTL) also places a positive locking force against the wheel tread, but the total lock brake (TTL) simultaneously locks the wheel and the swivel for a complete stationary position. 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. Listing is for a set of four (4) Service Caster Series #30 casters, two (2) swivel and two (2) rigid casters, with 5" diameter by 2" wide maroon polyurethane tread on silver aluminum core wheels capable of supporting a total weight of 3,600 lbs. (900 lbs. per caster).When searching for a reliable and durable solution to your caster needs, rely on Service Caster Series 30 polyurethane aluminum wheel casters. The Series #30 features heavy duty polyurethane wheels that are chemically bonded to an aluminum core, providing a smooth roll over uneven surfaces without marking or marring floors. Finely crafted with a bright zinc plated finish and heat-treated ball bearing raceway, these versatile casters are ideal for a wide range of applications. Use on 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.