Caster Wheel Materials: PU vs Rubber vs Nylon vs TPR — How to Choose

Walk into any caster catalog and you will see the same spec rows: wheel diameter, load rating, bearing type. But the single most important choice on the whole page is the one nobody advertises on the front cover — the wheel material. A 5 inch polyurethane caster on a smooth epoxy floor pushes like it is on ice. Put that same wheel on a cracked outdoor asphalt lot and it wears out in three months. The bracket, the bearing and the brake can all be perfect, and the wrong tread compound still makes the cart miserable.

This guide walks through the four materials you will actually encounter on industrial casters and castors — polyurethane, rubber, nylon and thermoplastic rubber (TPR) — plus the cast iron core options that sit underneath. By the end you should be able to look at a floor, a load and a duty cycle and say, without guessing, which wheel material belongs on the cart.

What Is a Caster Wheel Material, Anyway?

A caster wheel is not a single piece of plastic. Most industrial wheels are a composite: a load-bearing core (nylon, cast iron, aluminum or pressed steel) bonded or press-fitted to an outer tread that contacts the floor. The tread is what you feel when you push the cart — quiet or noisy, hard or soft, floor-marking or non-marking. The core is what keeps the wheel from deforming under load. When people say “polyurethane caster” they usually mean a wheel with a PU tread on an iron or plastic core.

The Four Main Tread Materials — Side by Side

There is also solid cast iron / forged steel wheels (hardest, highest load, loudest, used on overhead cranes and really heavy machinery) and aluminum-core PU for special weight-sensitive jobs. Those are niche — most buyers choose from the four above.

Material Deep Dive

1. Polyurethane (PU) — The Industrial Default

PU is the workhorse of modern warehouses. It is poured as a liquid around a cast iron or nylon core and cures into a tough, elastomeric tread. At about 95 Shore A it is firm enough to roll easily but compliant enough to roll over small debris without thumping. It does not mark epoxy or sealed concrete, resists oil and grease, and carries heavy loads without squishing. Our EH08 heavy-duty line uses 402 red flat-tread PU on a cast iron core, rated up to 250 kg per wheel at 125 mm diameter.

Watch out: PU does not like constant sunlight or temperatures over about 90 °C. For hot ovens or outdoor salt air, ask about high-temperature PU or a different compound.

2. Rubber — The Gentle But Softer Option

Rubber (natural or styrene-butadiene) is softer than PU, so it rolls quietly and absorbs vibration. It is the right pick when the cart carries sensitive instruments or runs on rough outdoor asphalt. The tradeoff: softer rubber deforms more under load, so load ratings are lower, and cheap rubber can leave black marks on light-colored floors. Specify non-marking rubber if floor appearance matters.

3. Nylon — Hardest, Loudest, Chemical-Proof

Nylon wheels (usually PA6 or PA66) are hard, smooth and nearly inert to chemicals. They roll with very low push effort on smooth floors and handle hot, oily or wet conditions that would chew through PU. The downside: they are loud on cracked concrete, they do not absorb shock, and on very smooth epoxy they can slip rather than roll when starting a heavy load. Choose nylon when the floor is rough, oily, or hot — not when your neighbors complain about noise.

4. TPR — The Quiet Light-Duty Choice

Thermoplastic rubber is a softer, lighter compound used on furniture casters, medical carts and office equipment. It is non-marking and quiet, but its load rating tops out around 150 kg per wheel. If your cart is under 300 kg total and lives indoors on tile or vinyl, TPR is fine. Anything heavier and you want PU.

The Core Matters As Much As the Tread

The same PU tread on a plastic core and on a cast iron core behaves differently under load. A plastic-core PU wheel is cheaper but will deform and flatten-spot if left parked under heavy load for weeks. An iron-core PU wheel keeps its shape, rolls true, and lasts longer. The difference shows up after six months, not on day one.

Five Common Mistakes Buyers Make

1. Buying the hardest wheel for the heaviest load. Harder does not mean better for the floor. A hard nylon wheel on epoxy is noisy and will scuff. Match tread to floor, not just to load.
2. Ignoring the core. Two “PU wheels” with the same diameter can last twice as long if one has an iron core. Ask what is inside.
3. Using indoor wheels outdoors. PU on asphalt wears fast. Rubber or nylon on rough outdoor concrete lasts longer.
4. Specifying non-marking without testing. Cheap rubber marks light floors. Ask for samples and push them on your actual floor before ordering a container.
5. Forgetting temperature. Standard PU tops out around 90 °C. If the cart sits near ovens or autoclaves, ask for high-temperature compound.

How to Choose — A Quick Decision Flow

Answer four questions and the material picks itself:

1. What is the floor? Sealed concrete / epoxy / vinyl → PU or TPR. Rough outdoor asphalt → rubber. Oily, wet or hot → nylon.
2. How heavy is the load? Under 300 kg per cart → TPR or light PU. 300–1,000 kg → iron-core PU. Over 1,000 kg → cast iron core PU or forged steel wheel.
3. Is noise a concern? Office, lab, hospital → rubber or TPR. Warehouse aisle, fine → PU. Outside or rough shop floor → nylon is acceptable.
4. Will the cart sit parked under load for days? Yes → iron core, not plastic core.

Worked Example

A 700 kg welding cart runs on sealed concrete in a fab shop, pushed 4–5 km a day, sometimes parked loaded overnight. Per wheel on four casters: 700 ÷ 4 = 175 kg. Add 30% safety margin → 227 kg per wheel. Pick a 5 inch (125 mm) iron-core PU caster rated 250 kg — exactly the EH08-11-125S-402 we spec on our product page. Nylon would roll but be loud; rubber would carry but deform; TPR would be too light. PU on iron core is the answer.

How Globe Caster Helps

Globe Caster — Foshan Global Caster Co., Ltd, Guangdong, China — has been making casters and castors since 1988. Our 156,000 m² facility runs in-house stamping, injection molding and PU pouring, so we control the tread compound, the core, and the bracket finish on one production line. We stock 600+ standard SKUs across light, medium and heavy duty ranges, and can mix wheel materials in one container — nylon wheels for the oily corner, PU wheels for the main aisle, TPR for the office carts. Typical lead time 30 days, 12-month warranty, ISO 9001 and ISO 14001 certified.

Not sure which material fits your floor? Send us a photo of the floor, the load per cart, and the duty cycle. We will recommend the compound and send samples so you can push them on your own concrete before committing to a bulk order.