Most buyers shortlist casters by wheel diameter and load first, and treat the wheel material as a detail. In practice the material decides how the wheel behaves every day after installation: how much noise it makes, whether it marks the floor, how it copes with debris and moisture, and how long it survives abrasive surfaces. Two casters with identical dimensions and ratings can behave completely differently because of the material.
This guide compares the four wheel materials in the KORONO range — polyurethane (PU), rubber, polypropylene (PP) and TPR — explains where each one fits, and lists what still has to be confirmed for a specific model before ordering.
What the wheel material actually decides
Wheel diameter, mounting dimensions and a confirmed load basis determine whether a caster fits and carries. The material determines how it feels and wears in service. Four properties are affected most:
- Noise. Hard wheels rolling on hard floors generate more noise than elastic ones.
- Floor marking. Some compounds leave marks; others roll clean.
- Wear on abrasive floors. Compounds differ in how they resist cutting, chipping and flat-spotting.
- Environment. Moisture, washdown and chemicals affect some compounds far more than others.
Polyurethane (PU)
Where it fits
Polyurethane is an elastic tread bonded over a core — the core is commonly iron, as in the KORONO heavy duty iron-core PU series. PU is commonly considered for equipment that runs long hours on smooth concrete because it can combine relatively low rolling resistance, abrasion resistance and floor-friendly behaviour. The exact compound and floor-marking result still need confirmation for the selected model. It cushions better than a hard plastic wheel, which protects both the load and the floor from vibration.
Watch-outs
On floors covered with metal swarf, grit or shards, debris can embed in the tread and cut it from the inside — a hard or debris-tolerant wheel suits those floors better. PU also has limits in prolonged wet, chemical or high-temperature exposure that must be confirmed for the specific compound rather than assumed. Bond quality between tread and core matters: a PU wheel is only as good as its bonding, which is a manufacturing question, not a catalogue question.
Rubber
Where it fits
Rubber wheels — represented by the KORONO heavy duty black rubber and gold-core rubber series — are commonly considered when low noise, cushioning and tolerance of small floor irregularities matter. The tread deforms around small debris and uneven floors instead of rolling over them, which makes rubber suitable for workshops where floors are never perfectly clean, and for equipment where noise and shock protection matter more than rolling efficiency.
Watch-outs
Rubber trades rolling efficiency for cushioning: under load it takes noticeably more effort to move than PU or PP. Depending on the compound, rubber can mark floor finishes — this varies by formulation and must be confirmed per model. "Rubber" is also a family, not a specification: hardness, rebound and ageing behaviour differ between compounds, and a series name does not establish any of them.
Polypropylene (PP)
Where it fits
PP is a hard, non-marking thermoplastic. It does not absorb water and can be a practical candidate for wet areas or washdown-adjacent zones. Chemical exposure, outdoor use and the exact PP grade still need confirmation for the selected model. The KORONO high-load PP series is one PP option with a catalogue set rating that must be confirmed for the selected model. The moulded construction also appears in the anti-winding PP series, intended for applications where threads or fibres can collect around the wheel area.
Watch-outs
The same hardness that makes PP durable makes it loud: on hard floors it generates the most noise of the four materials and transmits vibration into the load. It generally provides less cushioning than elastic wheel materials over thresholds and uneven surfaces. For thread- or fibre-prone environments and some wet applications, that trade can be appropriate; for noise-sensitive spaces, an elastic wheel material may be more suitable. Confirm the compound and operating environment before selection.
TPR
Where it fits
TPR (thermoplastic rubber) is the middle ground: a softer thermoplastic compound that rolls quieter and more gently than PP while sharing some of thermoplastic's cleanliness and non-marking behaviour. In the KORONO heavy duty TPR series and its light-duty counterpart, it is positioned for equipment where noise and floor protection are priorities but the application does not demand a full rubber compound.
Watch-outs
"TPR" covers a range of formulations with different hardness and wear behaviour — the label alone does not establish a hardness, test result or environmental limit, and this is stated on the series page itself. Confirm the compound for the selected model, particularly if the wheel will see moisture, chemicals or sustained loads.
The four materials side by side
The comparison below is qualitative — it describes relative behaviour between the four material families, not specifications of any series:
| Property | PU | Rubber | PP | TPR |
|---|---|---|---|---|
| Rolling noise on hard floors | Usually low–moderate | Usually low | Usually higher | Usually low |
| Floor marking | Confirm compound | Compound-dependent | Typically non-marking | Confirm compound |
| Abrasion resistance | Often high | Varies by compound | Often high | Varies by compound |
| Ride comfort over uneven floors | Moderate | Usually higher | Usually lower | Usually higher than PP |
| Moisture / chemical tolerance | Confirm per compound | Confirm per compound | Often favourable; confirm grade | Confirm per compound |
| Debris-covered floors | Inspect for tread damage | Can deform around small debris | Hard tread; confirm floor condition | Can deform around small debris |
| Rolling effort under load | Often lower than rubber | Often higher | Often lower | Moderate; confirm compound |
The questions that decide the material
Material selection becomes straightforward once five questions are answered:
- What is the floor? Smooth sealed concrete often leads buyers to compare PU; rough or debris-covered surfaces may favour an elastic tread; wet or washdown areas can make PP relevant, subject to grade and exposure confirmation.
- What is on the floor? Threads and fibres can collect around wheel assemblies, so compare an anti-winding design or a hard-wheel option rather than choosing by tread material alone.
- Does noise matter? If the equipment runs near people, compare rubber, TPR and PU before choosing a harder PP wheel; confirm noise requirements and floor conditions.
- Is there moisture or chemistry? Prolonged exposure eliminates some compounds immediately; this must be stated, not assumed.
- What does the wheel carry, and how does it move? Load basis and movement affect material choice together with everything else — the reasons a per-wheel figure cannot simply be divided from a set rating are covered in the load capacity guide, and the configuration question (rigid, swivel, brake) in the configuration guide.
What a material name does not tell you
One caution that applies to every supplier's catalogue, including this one: a material label attached to a series name does not by itself establish compound hardness, test results, temperature limits, chemical resistance or floor-marking behaviour. Those properties belong to a specific compound in a specific model, and they should be confirmed in the quotation — not inferred from the colour of the wheel or the name of the series. This is the same principle applied throughout the KORONO series pages: dimensions are published so you can screen fit; the specification of the selected model is confirmed before the order.
Next steps
Browse the full caster catalogue by material, or go deeper on the ranges mentioned above. For the complete selection sequence — load basis, configuration, size, mounting, environment — read the seven-step caster selection guide.
When the floor, environment and load basis of your equipment are known, send the specification for a quotation. State the floor condition, any moisture or chemical exposure, and the noise requirement alongside the weight — those four facts narrow the material choice faster than anything else.