Castor wheels are the most-underspecified item in workshop fit-out. The wrong castor turns a $400 tool cabinet into something that wobbles when you push it, won't roll over a power cord, marks the polished concrete floor, and works loose at the bolt after three months of use. The right castor — matched to the load, the floor, and the application — disappears into the background and just works for a decade. This guide answers the questions AU workshops actually have on castor selection: stem vs bolt hole vs plate mounting, polyurethane vs rubber vs nylon vs cast iron wheel material, load capacity sizing rules, swivel flutter fixes (the #1 forum complaint), brake type selection (top lock vs total lock), and EasyRoll series decoded across the full G1/G2/G6/G7/H6/I2/I6/J3/J7 range stocked at AIMS.
Honest scope: AIMS stocks 30 EasyRoll castor products in our castors collection — full range from $1.75 (50mm hooded nylon stem castor with brake) through $71.02 (pneumatic swivel) and $48.09 (G7 stainless brake variants for marine/food-grade). AIMS does NOT stock Tente (European premium engineering), Blickle (German specialty), Colson (US), Albion, Hamilton or Faultless — these are specialty imports flagged source-on-request via our supplier network. EasyRoll is the AU dominant industrial castor brand and covers ~95% of workshop, equipment, mobile-rack and material-handling castor needs.
The Three Castor Decisions That Matter
Buying castors comes down to three sequential decisions, in this order:
- Mounting type — how the castor attaches to your equipment (plate, bolt hole, or stem). This is determined by the equipment frame, not by you.
- Wheel material — polyurethane, rubber, nylon, cast iron, or pneumatic. This is determined by the load, the floor surface, and the operating environment.
- Brake / swivel configuration — fixed, swivel, swivel-with-brake, or total-lock. This is determined by how the equipment will be used and parked.
Get those three right and the castor lasts a decade. Get any one wrong and you're replacing castors within a year. The rest of this guide walks each decision in turn.
Mounting Type — Plate vs Bolt Hole vs Stem
Three mounting styles dominate industrial castor selection. Each has specific strengths and a typical application class.
| Mounting Type | How It Mounts | Load Strength | Best For | Weakness |
|---|---|---|---|---|
| Top Plate | Rectangular plate with 4 corner bolt holes, attaches flat to underside of equipment frame | Highest — load distributed across 4 bolts + large mounting area | Heavy industrial carts, machinery stands, heavy tool cabinets, mobile racks with flat steel frame | Needs flat reinforced mounting surface; larger footprint; drilling 4 holes |
| Bolt Hole | Single central bolt hole through castor body, attaches via single through-bolt + nut | Medium — single-bolt load path | General workshop trolleys, parts bins, mobile workstations, lighter equipment | Single bolt = single failure point; bolt hole can wear oval under repeated load |
| Threaded Stem | Threaded stud extending from castor body, screws into matching tapped hole or sleeve insert | Light-medium — depends on stem size + frame thread quality | Office chairs, light mobile equipment, tubular leg frames with sleeve inserts | Stem can loosen under cyclic load; frame thread must match stem exactly |
Plate Mounting
Top-plate castors give the highest load capacity because the four corner bolts distribute the load across a large mounting area. For any cart or stand carrying 50 kg+ per castor, plate mounting is the default. The trade-off is the larger footprint and the need for a flat, reinforced mounting surface.
AIMS stocks plate-mount castors across the full EasyRoll range: G1 Grey Rubber Swivel Plate ($6.48), I2 Cast Iron Swivel Plate ($6.53), I6 Blue Rubber Swivel Plate ($22.77), G7 Stainless Plate Brake Rubber ($48.09), J3 Cast Iron Swivel Plate ($53.71), J7 150mm Cast Iron Swivel ($63.13).
Bolt Hole Mounting
Bolt hole castors mount via a single central through-bolt — quick to install, easy to replace, lower part count. They're the workshop standard for general trolleys, mobile parts racks, and light-to-medium equipment. The single-bolt load path is the weakness: under cyclic shock load the bolt hole can wear oval, allowing the castor to wobble or work loose.
AIMS bolt-hole range: G1 Grey Rubber Bolt Hole ($5.18), G2 Twin Wheel Bolt Hole ($10.20), G6 Urethane Bolt Hole ($20.05), I6 Elastic Rubber Bolt Hole ($26.50), G7 Stainless Urethane Bolt Hole Brake ($48.09).
Threaded Stem Mounting
Stem castors are the smallest mount type — a threaded stud screws into a matching tapped hole or sleeve insert in the equipment frame. Used for office chairs, light medical/lab equipment, tubular-leg frames with sleeve inserts, and equipment where you want to swap castors without dismantling. The stem thread must match the receiving thread exactly (M10, M12, 5/16", 3/8", 1/2" UNF are all common).
AIMS stem range: G1 Grey Rubber Stem Swivel ($7.92), G1 Stem with Brake ($9.62), H6 PU Twin Wheel Stem ($19.18), H6 PU Stem with Brake ($22.82), G2 75mm Stem with Brake ($33.04), and the 50mm Hooded Nylon Stem with Brake ($1.75) — entry-level office chair / light equipment castor.
Wheel Material — Polyurethane vs Rubber vs Nylon vs Cast Iron vs Pneumatic
Wheel material drives load capacity, floor protection, noise, shock absorption, and chemical/temperature resistance. The wrong material on the right mount still fails. Choose wheel material to match your load, floor surface, and operating environment.
| Material | Load Capacity | Floor Protection | Shock Absorption | Noise | Best For |
|---|---|---|---|---|---|
| Polyurethane | High (combines hard polymer load + elastic grip) | Excellent — non-marking | Good | Quiet | Workshop default — concrete floors, tile, vinyl, mixed surfaces |
| Rubber | Light-medium | Excellent — soft, non-marking | Excellent | Very quiet | Light loads, rough/uneven floors, noise-sensitive environments (hospitals, labs) |
| Nylon / Polypropylene | Highest (glass-filled nylon up to 1,000+ kg per wheel) | Poor — marks softer floors | None | Noisy | Heavy loads on smooth, hard, easy-clean surfaces (warehouse concrete, factory floor) |
| Cast Iron | Very high | Marks most floors | None | Very noisy | Heavy industrial, hot environments (foundries, forges), iron-on-iron acceptable |
| Pneumatic (air-filled) | Medium | Excellent | Best | Quiet | Outdoor, rough terrain, gravel, uneven ground — wheelbarrow style |
Polyurethane (PU) — The Workshop Default
Polyurethane wheels combine the benefits of rubber (grip, shock absorption) with the benefits of hard plastic (load capacity, wear resistance, chemical resistance). PU is the default workshop choice for general-purpose castors carrying 50-500 kg per wheel on concrete, tile or vinyl floors. The forum-validated consensus from Caster Concepts and Midwest Caster: PU outperforms rubber on load capacity and outperforms nylon on floor protection — the all-rounder.
AIMS PU range: H6 White PU Twin Wheel Stem ($19.18), G6 Urethane Bolt Hole ($22.27), G6 Urethane Brake Bolt Hole ($21.91), G7 Stainless PU Brake ($48.09).
Rubber — Quiet + Shock-Absorbing
Rubber wheels excel at shock absorption and quiet operation. The elasticity of rubber absorbs vibration from rough or uneven floors and dampens noise dramatically — important in hospitals, labs, schools, hotels, food service, and noise-sensitive workshops. The trade-off is lower load capacity than PU and the wheel can compress under static load (a parked trolley can develop flat spots if heavy).
AIMS rubber range: G1 Grey Rubber Stem ($7.92), G1 Grey Rubber Plate ($6.48), G2 Grey Rubber Twin Wheel Bolt Hole ($10.20), I6 Blue Rubber Plate ($22.77), I6 Elastic Rubber Bolt Hole ($26.50).
Nylon (Polypropylene) — Highest Load, Hardest Wheel
Glass-filled nylon and polypropylene wheels carry the highest load capacity of any common workshop castor wheel material — up to 1,000+ kg per wheel on premium sizes. The trade-off is that nylon doesn't absorb shock, marks softer floors (vinyl, polished concrete sealer, painted floors), and is noisy. Use on smooth hard surfaces only — warehouse concrete, factory tile, industrial epoxy floors. Avoid on hospital, lab, retail, hospitality flooring.
AIMS nylon entry: 50mm Hooded Nylon Stem with Brake ($1.75) — light office/lab castor.
Cast Iron — Heavy Industrial + High Temperature
Cast iron wheels are reserved for heavy industrial applications and high-temperature environments where polymer wheels would melt or degrade. Foundries, forges, kilns, ovens, and heavy material handling on concrete floors. Iron-on-iron is acceptable in industrial settings; iron-on-anything-else marks floors badly. Very noisy.
AIMS cast iron range: I2 Cast Iron Fixed Plate ($5.18), I2 Cast Iron Swivel Plate ($6.53), J3 Cast Iron Fixed Plate ($44.91), J3 Cast Iron Swivel Plate ($53.71), J7 150mm Cast Iron Swivel ($63.13).
Pneumatic — Outdoor + Rough Terrain
Air-filled pneumatic castors are the wheelbarrow-style option for outdoor use, rough terrain, gravel, grass, uneven ground. Best shock absorption of any wheel type. Trade-off: can puncture; needs inflation maintenance; lower load than solid wheels.
AIMS pneumatic: EasyRoll Swivel Pneumatic Castor ($71.02).
Floor Surface Compatibility — Which Wheel for Which Floor
| Floor Surface | Recommended Wheel | Avoid |
|---|---|---|
| Bare concrete (warehouse, workshop, factory) | Polyurethane, nylon (heavy), cast iron (industrial heavy) | Pneumatic (overkill); soft rubber (low capacity) |
| Sealed/polished concrete (showroom, retail) | Polyurethane, soft rubber | Nylon, cast iron (mark the sealer) |
| Vinyl / lino (hospital, lab, kitchen) | Polyurethane, rubber — both non-marking | Nylon, cast iron (tear surface) |
| Tile (commercial, food service) | Polyurethane (preferred), rubber | Nylon (cracks grout), cast iron |
| Hardwood / laminate | Soft polyurethane, rubber | Nylon, cast iron, hard PU (dent) |
| Carpet (office) | Hard polyurethane, nylon — roll efficiently | Soft rubber (drag); pneumatic |
| Outdoor (gravel, uneven) | Pneumatic | Hard wheels (no shock absorption) |
| Hot environment (foundry, oven area) | Cast iron, high-temp PU rated | Standard rubber (melts/softens above 80°C) |
| Wet / marine / chemical (G7 Stainless) | G7 Stainless body + PU or rubber wheel | Carbon steel body (corrodes) |
Brake Options — Top Lock vs Total Lock vs Directional
Castor brakes are not all the same. The right brake type depends on whether you need to stop the wheel rolling, stop the swivel rotating, or stop both.
| Brake Type | What It Locks | Mandatory For |
|---|---|---|
| Top Lock (wheel brake) | Wheel only — castor can still swivel | Trolleys parked temporarily; preventing rolling but allowing positioning |
| Total Lock (wheel + swivel) | Wheel AND swivel — castor fully stationary | Office chairs at rest; mobile workbenches in use; medical equipment; stationary tool cabinets |
| Directional Lock | Swivel only — castor forced to track straight | Long carts that must track straight (medical, supply trolleys) |
The most common braking mistake: putting top-lock-only brakes on a mobile workbench. The wheel doesn't roll, but the workbench can still swivel — and slowly drifts as you lean on it. For any stationary mobile equipment that's actively being worked on, use total lock brakes on at least 2 of the 4 castors.
AIMS braked range: G1 Stem Brake ($9.62), G1 Plate Brake ($7.53), G2 Twin Wheel Brake ($12.92), H6 PU Stem Brake ($22.82), G6 Urethane Brake ($21.91), G6 Rubber Brake ($26.46), I6 Blue Rubber Plate Brake ($32.76), and G7 stainless brake variants ($48.09 each).
Load Capacity Sizing — Design for 3 of 4 Castors
The single most-common castor sizing mistake is to divide total load by 4 (the number of castors). This is wrong. On any real floor — even one that looks flat — small irregularities mean only 3 of the 4 castors carry load at any moment. The fourth is in the air or just barely contacting.
The correct sizing rule: total load ÷ (number of castors − 1) = required capacity per castor. For a 400 kg load on 4 castors, that's 400 ÷ 3 = 133 kg per castor minimum capacity. Round up to the next available size with a safety factor of at least 1.5× for daily use, 2× for high-cycle or mobile equipment.
| Total Load (Equipment + Contents) | Per-Castor Capacity (4 castors) | With 1.5× Safety Factor | EasyRoll Series |
|---|---|---|---|
| 50 kg (light parts trolley) | 17 kg | 26 kg | G1 Series |
| 100 kg (workbench) | 33 kg | 50 kg | G1, G2 Series |
| 250 kg (tool cabinet + tools) | 83 kg | 125 kg | G6, H6, I6 Series |
| 500 kg (heavy parts trolley) | 167 kg | 250 kg | I6, I2, J3 Series |
| 1,000 kg (machinery stand) | 333 kg | 500 kg | J3, J7 Cast Iron Heavy |
| 2,000 kg+ (heavy industrial) | 667 kg+ | 1,000 kg+ | J7 + specialty heavy castors (source on request) |
Castor Wobble & Flutter — The #1 Forum Question
The Three Causes
- High speed — caster flutter increases dramatically above walking pace. A castor that's fine at 2-3 mph (walking) may shimmy uncontrollably at 8-10 mph (running with a cart).
- Loose swivel — bearings worn or axle bolt loose. The swivel head wobbles before the wheel even moves. Most common failure mode after long service.
- Misalignment — castor not square to equipment frame; bent stem; uneven floor + uneven mounting. Caster geometry depends on the swivel axis being perpendicular to the floor.
The Five Fixes
- Extend the swivel lead — the offset between the swivel axis and the wheel axle (where the wheel contact patch sits relative to the swivel pivot). Longer lead = better tracking. Premium castors are designed with optimal lead; cheap castors often have inadequate offset.
- Reduce operating speed — don't run with the cart. Walking pace eliminates most flutter.
- Inspect bolts + bearings — turn the equipment upside down monthly, check every axle bolt and swivel bolt for tightness. Lubricate swivel bearings annually.
- Increase wheel friction — softer wheel (rubber over nylon, PU over hard PU) has larger contact patch and dampens flutter oscillation. Less efficient roll but less wobble.
- Replace worn parts — bent stems, oval bolt holes, rusty bearings, cracked wheels all cause flutter. Don't try to fix worn castors; replace them.
Common Castor Mistakes
| Mistake | Consequence | Fix |
|---|---|---|
| Sizing for 4 castors carrying load | Premature failure; castors deform under load | Design for 3-of-4 castors + 1.5× safety factor |
| Wrong wheel for floor | Marked or torn floor; expensive remediation | PU/rubber on sensitive floors; nylon/iron on industrial concrete only |
| Top lock brake on mobile workbench | Workbench drifts when leaned on | Total lock brake on at least 2 of 4 castors |
| Stem castor in oversized hole | Stem loose, castor wobbles + walks out | Match stem to exact tapped thread size; use sleeve insert if needed |
| All-swivel on long cart | Cart drifts laterally, hard to track straight | 2 swivel + 2 fixed (steering geometry) or directional-lock castors |
| Mounting bolts not torqued to spec | Bolts work loose under cyclic load; castor walks off frame | Torque bolts to spec; check monthly; thread-locker on long-life mounts |
| Pneumatic castors indoor on hard floor | Overkill — soft tyre absorbs effort, makes rolling harder | Pneumatic outdoors only; PU or rubber indoor |
| No brake on equipment that needs to park | Equipment rolls away; pinch injuries; equipment damage | Total lock brake on every mobile workbench, parts cart, machinery stand |
| Mixing wheel sizes / materials on same cart | Uneven contact, wobble, poor rolling | Always use matched set of 4 identical castors |
| Castor on hot surface above 80°C | Rubber softens, melts, deforms permanently | High-temp PU or cast iron for hot environments |
EasyRoll Series Decoder — What Each Series Is For
EasyRoll codes their castors by series letter and number. Once you know the series, you know the wheel material, capacity range, and typical use case.
| Series | Wheel Material | Capacity Range | Typical Use |
|---|---|---|---|
| G1 | Grey rubber, light-medium | 30-70 kg per castor | Light trolleys, parts bins, mobile workstations |
| G2 | Grey rubber, twin wheel | 50-100 kg per castor | Office, light commercial, smoother rolling |
| G6 | Grey rubber + urethane bolt hole | 80-150 kg per castor | Workshop trolleys, tool cabinets, mobile parts racks |
| G7 | Stainless steel body + PU/rubber wheel | 100-200 kg per castor | Marine, food-grade, wet environments, chemical exposure |
| H6 | White polyurethane twin wheel | 60-120 kg per castor | Hospital, retail, food service — quiet, non-marking |
| I2 | Cast iron plate | 100-200 kg per castor | Heavy industrial, foundry, hot environments |
| I6 | Blue rubber + elastic rubber, plate | 120-300 kg per castor | Heavier workshop carts, machinery stands |
| J3 | Cast iron plate (heavier than I2) | 300-600 kg per castor | Heavy industrial machinery stands, kilns, ovens |
| J7 | 150mm cast iron heavy plate | 600-1,000 kg per castor | Very heavy industrial — large equipment, transport carts |
Swivel + Fixed Combinations
How you combine swivel and fixed castors on a cart determines how it steers:
- 4 swivel — maximum manoeuvrability. Cart turns in place, slides sideways. Best for confined spaces (workshops, kitchens, parts bins). Worst for straight-line tracking — drifts laterally.
- 2 swivel + 2 fixed — shopping cart configuration. Fixed castors give straight-line tracking; swivel castors give steering. Best for long carts and corridors.
- 4 fixed — no steering — castors only roll one direction. Used on rolling racks that travel between fixed points (rail-style).
- Diamond layout (5 or 6 castors) — large carts use 4 corner swivels plus 1-2 fixed castors mid-axle for tracking + manoeuvrability hybrid.
Installation and Maintenance
- Torque mounting bolts to specification — manufacturer publishes torque values. Use a torque wrench. Re-check after first month of service.
- Thread-locker on long-life mounts — Loctite 243 (medium strength) on bolt holes and stem threads where vibration could loosen the joint over time. See our Loctite 243 guide.
- Monthly inspection — turn equipment over (or jack up one side at a time), check each castor for wheel damage, bolt tightness, swivel free-rotation, brake function.
- Lubricate swivel bearings annually — most premium castors use sealed bearings (maintenance-free); budget castors benefit from a light grease application.
- Replace as a set — when one castor fails, the others are probably close behind. Replace all 4 with matched units.
- Don't run castors into power cords or hose lines — universal forum complaint. Plan cable management before specifying castors.
AIMS Castor Range — Supply Ladder
Light duty / office-lab tier ($1.75-$10): 50mm Hooded Nylon Stem with Brake ($1.75), G1 Grey Rubber Bolt Hole ($5.18), I2 Cast Iron Fixed Plate ($5.18), G1 50mm Fixed Plate Rubber ($5.41), G1 Grey Rubber Swivel Plate ($6.48), I2 Cast Iron Swivel Plate ($6.53), G1 Swivel Plate Brake ($7.53), G1 Grey Rubber Stem ($7.92), G1 Stem with Brake ($9.62).
Workshop standard tier ($10-$30): G2 Twin Wheel Bolt Hole ($10.20), G2 Twin Wheel Bolt Hole Brake ($12.92), H6 PU Twin Wheel Stem ($19.18), G6 Urethane Bolt Hole ($20.05), G6 Urethane Brake Bolt Hole ($21.91), G6 Urethane Premium ($22.27), H6 PU Stem Brake ($22.82), I6 Blue Rubber Plate ($22.77), G6 Urethane Brake Heavy ($26.43), G6 Grey Rubber Brake ($26.46), I6 Elastic Rubber Bolt ($26.50), G6 Grey Urethane Premium ($28.26).
Heavy duty / specialty tier ($32-$71): I6 Blue Rubber Plate Brake ($32.76), G2 75mm Stem Brake ($33.04), J3 Cast Iron Fixed Plate ($44.91), G7 Stainless Plate Rubber Brake ($48.09), G7 Stainless Plate PU Brake ($48.09), G7 Stainless Bolt PU Brake ($48.09), J3 Cast Iron Swivel Plate ($53.71), J7 150mm Cast Iron Swivel ($63.13), EasyRoll Swivel Pneumatic Castor ($71.02).
Brand Reality — Stocked vs Source-on-Request
| Brand | Position | AU Availability |
|---|---|---|
| EasyRoll | AU industrial dominant — G/H/I/J series covers entry through heavy industrial | Stocked at AIMS |
| Tente (Germany) | European premium — engineered medical/hospital + heavy industrial | Specialty importer — source-on-request |
| Blickle (Germany) | Premium engineering — specialty AGV, heavy industrial, custom configurations | Specialty importer — source-on-request |
| Colson (US) | US industrial — Performa, Caster Royal lines, heavy duty | Specialty importer — source-on-request |
| Albion (US) | US industrial — heavy industrial + AGV specialty | Specialty importer — source-on-request |
| Hamilton (US) | US heavy industrial — large diameter, very heavy duty | Specialty importer — source-on-request |
| Faultless (US) | US industrial — broad workshop range | Specialty importer — source-on-request |
Selection Checklist
- Total load? Equipment weight + worst-case payload. Round up generously.
- Number of castors? 4 is standard; design for 3 of 4 carrying load (uneven floor).
- Per-castor capacity needed? Total load ÷ (n − 1) × 1.5 safety factor.
- Mounting type? Plate for highest load. Bolt hole for general workshop. Stem for office/light/tubular frames.
- Wheel material? PU = workshop default. Rubber = quiet/sensitive floors. Nylon = heavy on hard smooth concrete. Cast iron = heavy industrial or hot. Pneumatic = outdoor.
- Floor surface? Match wheel to floor — see compatibility table.
- Brake type? Total lock for stationary mobile equipment. Top lock for trolleys that just need to not roll. Directional lock for long carts.
- Swivel pattern? 4 swivel (manoeuvrability), 2 swivel + 2 fixed (tracking), diamond (large carts).
- Operating environment? Wet/marine/chemical = G7 stainless. Hot = cast iron or high-temp PU. Outdoor = pneumatic.
- Stem mount? Confirm exact thread size (M10, M12, 5/16", 3/8", 1/2" UNF) before ordering.
Frequently Asked Questions
What is a castor wheel and what does it do?
A castor (or caster) is a wheel mounted on a swivelling or fixed bracket that attaches to the underside of equipment, allowing the equipment to roll across a floor surface. Castors are used on tool cabinets, mobile workbenches, parts trolleys, machinery stands, office chairs, hospital beds, and any equipment that needs to be moved manually. Three key parts: the wheel, the bracket (with swivel/fixed/brake mechanism), and the mounting interface (plate, bolt hole, or stem).
What's the difference between castor and caster?
None — different spellings of the same word. "Castor" is the UK/AU/NZ spelling; "caster" is the US spelling. Both refer to the same product. AU and NZ industry mostly uses "castor"; US imports often arrive labelled "caster". The product is identical.
What size castor do I need for my workbench?
For a mobile workbench, calculate total load (bench weight + maximum tool/work load) and divide by 3 (not 4 — design for 3-of-4 castors carrying load on uneven floor). Add 1.5× safety factor. For a typical 100 kg workbench, that's 100 ÷ 3 = 33 kg, × 1.5 = 50 kg per castor minimum capacity. EasyRoll G6 or H6 series (workshop standard tier, 80-150 kg per castor) handles this comfortably.
Why do my castors wobble or shimmy?
Castor flutter (the technical name for wobble) has three common causes: (1) operating at too high a speed — flutter increases dramatically above walking pace; (2) loose or worn swivel bearings or axle bolts; (3) misalignment of castor to frame. Five fixes: extend the swivel lead (use a premium castor with proper geometry), reduce operating speed, inspect and tighten bolts monthly, use softer wheels for more friction (PU over hard nylon), replace worn parts rather than trying to fix them.
What is the difference between polyurethane and rubber castor wheels?
Polyurethane (PU) is the all-rounder — higher load capacity than rubber, non-marking, quiet, chemical/oil resistant, longer wearing. Rubber is softer — better shock absorption, quieter on rough floors, more forgiving on irregularities. PU wins on workshop concrete and tile; rubber wins where shock absorption and noise reduction matter most (hospitals, labs, hotels). Forum-validated consensus: PU is the workshop default; rubber is for specialty noise/shock applications.
What's the difference between top lock and total lock castor brakes?
Top lock (also called wheel lock) brakes lock the wheel only — the castor can still swivel. Suitable for trolleys parked temporarily where you don't need them to roll but want to reposition. Total lock brakes lock the wheel AND the swivel — castor fully stationary. Mandatory for mobile workbenches, office chairs at rest, medical equipment, and any equipment actively being worked on while stationary. Without total lock, the equipment slowly drifts as you lean on it.
How do I stop my office chair castors from marking the floor?
Replace the existing castors with soft polyurethane or rubber wheels. Office chairs typically come with hard plastic/nylon castors that mark vinyl, hardwood and laminate floors. The 50mm Hooded Nylon Stem with Brake is the cheap nylon option; upgrade to a soft PU equivalent with the same stem size to protect floors. Alternative: use a chair mat. Match the stem size exactly (most office chairs use 11mm or 7/16" stem).
What is the difference between plate, bolt hole and stem mounting?
Plate mount = rectangular plate with 4 bolt holes, highest load capacity, requires flat mounting surface and 4 holes drilled. Bolt hole mount = single central bolt through castor body, medium load, faster install with single bolt. Stem mount = threaded stud screws into matching tapped hole or sleeve insert, light-medium load, used for office chairs and tubular leg frames. The mount type is determined by the equipment frame, not by the operator.
Why won't my stem castor stay tight?
Three common causes: (1) stem size doesn't match the receiving thread exactly — measure and confirm M10, M12, 5/16", 3/8", 1/2" UNF; (2) receiving hole is worn oval from previous castor; (3) no thread-locker on a high-vibration application. Fixes: use the correct stem size, replace worn receiving holes with sleeve inserts, apply medium-strength thread-locker (Loctite 243) to the stem before installation.
What castor do I need for outdoor or rough terrain use?
Pneumatic (air-filled) castors are the standard outdoor option — best shock absorption, handles gravel, uneven ground, grass. Trade-offs: can puncture, needs inflation maintenance, lower load capacity than solid wheels, indoor rolling effort is higher because the soft tyre absorbs energy. AIMS stocks the EasyRoll Swivel Pneumatic Castor ($71.02) for these applications.
Can I mix castor sizes or types on the same cart?
No. Always use a matched set of 4 identical castors. Mixing sizes or wheel materials creates uneven contact (one castor lifted off the floor at all times), wobble, and uneven wear. The set should be: same wheel diameter, same wheel material, same bracket type, same load rating. If one castor fails, replace all 4 — the others are probably close behind anyway.
What is the load capacity rule for 4 castors?
Total load ÷ (number of castors − 1) = required capacity per castor. For 4 castors, divide load by 3, not 4. This accounts for the fact that on any real floor, only 3 of 4 castors carry load at any moment — the fourth is in the air or barely contacting. Then add 1.5× safety factor for daily use or 2× for high-cycle/heavy duty equipment. For a 400 kg load on 4 castors, that's 400 ÷ 3 = 133 kg, × 1.5 = 200 kg minimum per castor.
Are there castors for marine, food-grade or chemical environments?
Yes — EasyRoll G7 Series stainless steel castors ($48.09) are the marine, food-grade and chemical environment option. Stainless steel bracket body + PU or rubber wheel. Suitable for wet environments, food processing, pharmaceutical, chemical exposure, coastal/marine workshops, swimming pool deck areas. Standard carbon steel castors will corrode rapidly in these environments.
How do I know what stem size my office chair uses?
Remove one existing castor and measure the stem. Common sizes: 11mm (7/16") is the universal office chair stem size. Industrial stem castors use M10, M12, 5/16", 3/8" or 1/2" UNF. If the receiving hole is integrated into the chair leg (not a removable sleeve), the new castor stem must match exactly — adapters can sometimes accommodate small mismatches. When in doubt, take the existing castor to AIMS for matching.
How often should I replace workshop castors?
Premium castors on standard workshop use typically last 5-10 years before bearings wear or wheel material degrades. Indicators it's time to replace: visible wobble/flutter, wheel cracks or deformation, brake doesn't hold, bracket cracks, swivel won't free-rotate even when lubricated, mounting bolt holes oval-worn. Replace as a matched set of 4 — single-castor replacement creates uneven contact and accelerates wear on the others.
For complete workshop fit-out context, see our companion guides: Loctite 243 medium strength threadlocker (for castor mounting bolts in vibration applications), drum handling equipment guide (drum dollies use castors), storage bins guide (mobile bin racks), tool box guide (rolling tool cabinets), vehicle hoist guide (workshop fit-out).
Need help selecting the right castors for your equipment or specific load requirement? Browse the full castors collection (30 EasyRoll products), call AIMS Industrial on (02) 9773 0122, or contact our trade team — we'll match the castor to your load, floor and environment, and source specialty options (Tente, Blickle, Colson, Albion, Hamilton, Faultless) through our supplier network.