Caster Wheel Load Capacity by Material: Rubber, Polyurethane, Nylon, Steel and Cast Iron Compared

Screen out materials that cannot cover your per-wheel load

Start by comparing your calculated per-wheel load against the reported capacity band for each material family. A band is a screening filter, not a specification: capacity moves with wheel diameter, tread width and material thickness, so a material that clears your number in one size may not in another 13–15 .

At a 5-inch wheel, one source reports polyurethane 500–1,500 lb, nylon 800–2,500 lb, rubber 200–500 lb, cast iron 1,000–3,000 lb and forged steel 2,000–10,000+ lb 14 . Another reports polyurethane 800–2,000+ lb and rubber topping out around 500 lb 3 .

In metric terms, a third reports rubber up to 200 kg, polyurethane 200–900 kg, nylon 400–1,200 kg and cast iron/steel 1,000 kg and above 18 . If your per-wheel load sits above the rubber band, rubber is out on capacity before you compare anything else.

If it sits above the polyurethane band, you are looking at nylon or a metal wheel. The ordering rubber < polyurethane < nylon < cast iron < steel holds across the sources that give multiple materials 3 , 14 , 18 .

But the numbers behind it do not line up, so treat the band as a first cut and confirm the actual rating later 14 .

Check the material is offered at your diameter and tread width

A material that clears your load on paper still has to exist at the wheel size your cart needs. Larger wheels and wider treads spread the load over a larger area, which reduces pressure on the floor and the caster and rolls more easily over obstacles 13 , 15 .

That is why the same material carries different numbers at different diameters. At 2 inches, one source rates wheels from roughly 75–300 lb per wheel depending on material and tread width, with a four-wheel setup totalling 300–1,200 lb 1 .

At 5 inches the reported bands are much higher 14 . In one 5" x 2" Series 40 line, the same rig carries polyurethane at 800 lb, phenolic at 1,000 lb, steel at 900 lb and rubber on cast iron at 400 lb 10 .

A manufacturer's overall catalogue spans 25 kg to 2,000+ kg per caster across 1-inch to 12-inch-plus diameters 8 . And one stainless line covers 200 lb to over 1,200 lb per caster at 3 to 8 inches 5 .

So before you commit to a material, confirm the supplier offers it at your diameter and tread width, and ask for the rating at that exact size rather than the family band.

Weigh the capacity ceiling against floor damage and noise

Once two or three materials survive the load screen, the deciding trade-off is usually capacity against floor protection. Harder materials carry higher loads because their compressive strength is higher, but the same hardness concentrates pressure on the floor, so the material choice sets both the capacity ceiling and the floor damage risk 14 , 16 .

Polyurethane sits in the middle: it is reported above rubber and below nylon and the metals on capacity 3 , 14 , 18 , and it is positioned as non-marking and floor-protective 16 .

Rubber is the quietest and gentlest option — one supplier reports it 5 to 8 dB quieter than polyurethane on tile and gentler on delicate floors 3 — but it carries the least load.

Nylon is reported above rubber and polyurethane on capacity with low rolling resistance, but performs poorly on delicate floors and at extreme temperatures 11 , 14 , 18 . Steel and cast iron carry the highest reported ceilings 3 , 14 , 18 and are suited to harsh environments, but they offer no floor protection 10 , 16 .

If the floor is finished and the load is light, rubber or polyurethane is the direction. If the load is heavy and the floor can take it, the metals are the direction.

The sources do not settle which material is best overall — only which trade-off you are buying.

Reject the material if the operating environment disqualifies it

Capacity and floor protection are not the only filters. Environment can rule out a material that wins on load, so run these checks before you request a quote.

• ✓Oven or process heat above 200°F: one source indicates phenolic rather than polyurethane or rubber.
• ✓High-moisture environment: one source reports polyurethane tread separating from the wheel, making it unsuitable.
• ✓Daily washdown with hot water, caustic cleaners or sanitizing chemicals: one supplier describes stainless steel casters as a maintenance and compliance necessity.
• ✓Extreme temperatures or corrosive chemicals: one source reports nylon does not hold up, making it a poor fit for food processing.
• ✓Delicate or finished flooring: steel and cast iron offer no floor protection and can mark soft floors.

Apply a selection margin so the rating is not at the edge of the band

The sources give selection rules rather than a standard-mandated rating basis, so the margin you apply is your own protection against an optimistic figure. One source advises selecting wheels rated at least 25% above the calculated per-wheel load 1 .

Another uses a 3-corner rule: total loaded cart weight divided by 3, plus a 20% safety factor 18 . A third simply says divide the total load by the number of casters and choose a wheel with slightly higher capacity 22 .

These rules do not agree, and none of them is presented as a manufacturer or standard requirement. Pick one, state it on the RFQ, and ask the supplier to confirm the rating basis behind their number.

Static or dynamic — so your margin is applied to a figure you can compare 14 .

Check rolling effort if the cart is pushed by hand

On a hand-pushed cart, a material that clears the load can still be the wrong pick if it rolls hard.

Soft treads roll harder: in one 5" x 2" Series 40 line, rubber on cast iron is reported with higher rolling effort at 400 lb capacity, while steel is reported with low rolling effort at 900 lb 10 .

In the same series, phenolic is reported with very low rolling effort at 1,000 lb and polyurethane with low-to-moderate rolling effort at 800 lb 10 . Nylon is reported with low rolling resistance 14 , 18 , which matters if the cart is moved frequently.

The sources do not publish measured rolling-resistance or starting-effort values at rated load. So the comparison here is qualitative — if push effort is critical, ask the supplier for the rolling-effort data on the specific wheel.

Sanity-check the budget direction before requesting quotes

Cost is driven by material, load capacity, wheel size and type, and bearing type, and casters designed for heavier loads require more robust materials and construction, which raises cost 20 , 21 . That means a higher-capacity material is generally the more expensive route.

But the sources do not publish a per-material price comparison at equal load, so you cannot rank the five materials on price from this evidence 20 , 21 . When you request quotes, force the comparison onto a common basis: same load per wheel, same duty cycle, same wheel and bearing, same mounting configuration.

Ask each supplier to state which cost drivers are included in their price and which are excluded 21 .

Where the sources disagree on capacity bands

The bands do not line up across sources, and the disagreement is the reason to confirm the rating on the supplier's data sheet rather than trusting any single band.

The differences track wheel size and rating basis, neither of which is stated consistently, so treat each figure as that source's observation at its own conditions 3 , 10 , 14 , 17 , 18 .

What the sources do not establish

• No source provides a rated capacity table at a specified wheel diameter and tread width for all five materials on a common rating basis (static vs. dynamic).
• No quantitative capacity-vs-diameter or capacity-vs-tread-width scaling relationship for any material.
• No Shore A/D hardness values for any material.
• No measured rolling resistance or starting effort values at rated load.
• No numeric temperature ranges or chemical-resistance ratings per material.
• No per-material cost or price ranking at comparable load capacities.
• No manufacturer- or standard-specified safety factor (e.g., 3:1 or 4:1) per material.
• No data on cast iron specifically as distinct from steel in most capacity tables (often grouped as 'metal' or 'cast iron/steel').