Caster Spec Guide

Caster specifications come down to a short list: load capacity, wheel diameter, wheel material, bearing type, mount type, and swivel radius. Read those six correctly and you can match almost any caster to its job. Capacity and floor surface drive most of the decision; everything else refines it.

The specifications that matter

Load capacity Rated weight per caster. Size it above the real per-caster load (see the formula below).
Wheel diameter Larger wheels roll easier, clear debris, and carry more. Most industrial casters run 3 to 8 in.
Wheel material Drives floor protection, capacity, rolling resistance, and chemical/heat tolerance.
Tread width Wider tread spreads load and protects soft floors; narrow tread turns easier.
Bearing type Precision ball, roller, or plain. Sets rolling effort, speed, and maintenance.
Mount type Top plate (bolts to a flat plate) or stem (threads/presses into a socket).
Swivel vs. rigid Swivel rotates 360° for steering; rigid runs straight for tracking and capacity.
Swivel radius (offset) Horizontal distance from the kingpin center to the wheel contact. Larger offset swivels easier and carries more, but needs clearance.
Overall height Floor to top of plate/stem seat. Match it to keep equipment level.
Brake / lock Wheel brake, total-lock, or swivel lock for positioning and safety.
Temperature range Match the wheel and bearing to ovens, freezers, or wash-down environments.

Load capacity comes first

Capacity is the spec to get right before anything else. Calculate the load each caster must carry, then choose a rating above it:

Capacity per caster = (equipment weight + maximum load) ÷ (number of casters − 1)

Dividing by one fewer caster covers uneven floors, where one wheel can lift off. Distinguish static capacity (sitting still) from dynamic capacity (rolling under load); manufacturers rate for dynamic use at a defined speed. For towing, powered carts, or shock loads, add margin and consider spring-loaded or larger-diameter wheels.

Wheel material quick reference

  • Polyurethane on iron — the all-around industrial choice. High capacity, floor-friendly, non-marking, resists abrasion, oils, and many chemicals. Best for concrete and finished floors.
  • Phenolic — high capacity, hard, low rolling resistance, tolerates heat and oil. Can mark soft floors and rides hard over debris.
  • Cast iron / forged steel — maximum capacity and heat resistance for rough or hot floors. Noisy and not floor-friendly.
  • Nylon — high capacity, chemical- and moisture-resistant, good for wash-down. Hard and noisy.
  • Thermoplastic rubber (TPR) — quiet, non-marking, easy rolling for light-to-medium indoor loads.
  • Solid / soft rubber — cushioned and quiet; protects floors and fragile loads. Lower capacity, higher rolling resistance.
  • Pneumatic (air-filled) — cushioning for rough or outdoor terrain. Lower capacity and needs inflation upkeep.
  • Stainless & specialty — corrosion resistance for wash-down, plus high-temp and ESD options.

Bearings and mounts

Bearings: precision ball bearings roll smoothly at higher speeds and moderate-to-high loads; roller bearings carry the heaviest manual loads with more effort; plain or sealed bearings cut maintenance for wash-down and dirty environments.

Mounts: choose plate casters for carts, racks, and most equipment, or stem casters for chairs, tubular frames, and tight sockets. Then decide swivel for steering or rigid for tracking; a typical cart pairs two of each. Replacing the wheel only? See wheels only.

All Deals Plate Stem Swivel Rigid Wheels Only

Frequently asked questions

How do I calculate the load capacity I need?
Add the equipment weight to the maximum load it will carry, then divide by the number of casters minus one. Dividing by one fewer caster accounts for uneven floors. Choose a caster rated above that number, and add margin for towing or shock loads.
What wheel material is best for concrete floors?
Polyurethane-on-iron is the best all-around choice for concrete and finished floors: high capacity, low rolling resistance, non-marking, and resistant to abrasion and chemicals. Use phenolic or cast iron when you need maximum capacity or heat tolerance and floor marking is acceptable.
What is swivel radius and why does it matter?
Swivel radius (also called offset) is the horizontal distance from the center of the swivel kingpin to the center of the wheel's floor contact. A larger offset swivels more easily and supports higher capacity, but it requires more clearance around the mount. Match it so the caster can rotate freely without hitting the frame.
Should I choose plate or stem casters?
Use top-plate casters when you have a flat surface to bolt to, which suits most carts, racks, and equipment. Use stem casters when the equipment has a single center socket or tube, common on chairs and hospital equipment. The mount must match your existing bolt pattern or socket exactly.

Spec it with help

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