Pick the wrong castors and you'll know about it fast: wheels that jam on the garage floor, a workbench that creeps while you're sawing, or a trolley that sags under its first real load. The good news is that choosing the right castor comes down to six simple questions. This guide walks you through each one.
Quick checklist
1. How much weight? 2. What size wheel? 3. Which wheel material? 4. Swivel or fixed? 5. Do you need brakes? 6. Plate or threaded stem fitting?
1. Work out the load rating you need
This is the most important step, and the one most people get wrong. Add the weight of the item itself to the heaviest load it will ever carry, then divide by three, not four.
Why three? On any floor that isn't perfectly level, one wheel will often lift slightly off the ground, leaving three wheels carrying the whole load. Sizing for three gives you a built-in safety margin.
WORKED EXAMPLE
A workbench weighs 60kg and you'll load up to 240kg of tools and materials on it. That's 300kg total. 300 ÷ 3 = 100kg per castor. Choose castors rated at 100kg or more each.
2. Choose the right wheel size
Bigger wheels roll more easily, ride over cracks, cables and thresholds with less effort, and generally carry more weight. Smaller wheels keep things low and discreet.
| Wheel size | Best for |
|---|---|
| 25mm | Low-profile furniture, drawer units, small boxes and display stands |
| 50mm | Tables, planters, storage units, light trolleys |
| 75mm | Medium trolleys, tool chests, mobile shelving |
| 100mm | Workbenches, garage equipment, heavier trolleys |
| 125mm to 150mm | Heavy-duty loads, machinery stands, rough or uneven floors |
3. Match the wheel material to your floor
Polyurethane (PU): the all-rounder. Quiet, smooth and kind to hard floors like wood, laminate and tiles, while still carrying good loads.
Rubber: the softest, quietest ride. Great for indoor furniture and delicate floors, and grips well on smooth surfaces.
Nylon: hard-wearing and easy to roll under heavy loads, but louder and harder on floors. Best for workshops and warehouses.
Tip: the harder the floor, the softer the wheel you want. On carpet, a harder wheel rolls more easily.
4. Swivel or fixed castors?
Swivel castors rotate 360°, so you can steer in any direction. Ideal for tight spaces.
Fixed castors only roll forwards and backwards, which keeps long items tracking straight.
For trolleys you push over longer distances, a popular setup is two swivel at the front and two fixed at the back. It steers like a shopping trolley and stays straight in a line. For furniture and workbenches that move around a room, four swivel castors give the most freedom.
5. Do you need brakes?
If the item needs to stay put while it's in use, yes. Workbenches, tool chests, machine stands and anything on a slope should have locking castors.
You don't always need brakes on all four wheels. Two braked castors (usually diagonally opposite) are enough for most furniture. For workbenches where you'll be sawing, hammering or drilling, four braked castors, or retractable workbench castors, give the most stable base.
6. Plate or threaded stem fitting?
Top plate castors screw or bolt onto a flat surface. They're the strongest option and suit workbenches, trolleys and flat-bottomed furniture.
Threaded stem castors screw into a threaded insert, which makes them ideal for chair legs, tube frames and slimmer furniture. Always check the thread size (for example M6 or M10) and stem length before you order. You'll find ours in the threaded stem castors range.
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Frequently asked questions
How do I measure a castor for replacement?
Measure the wheel diameter, the overall height from the floor to the mounting surface, and either the plate size and bolt-hole spacing or the stem thread and length.
Why won't my castors roll smoothly on carpet?
Small, soft wheels sink into carpet pile. Go for a larger diameter or a harder wheel material.
Can I mix braked and non-braked castors?
Yes, as long as they're the same height. Two braked plus two non-braked is a common, cost-effective setup.
Still not sure which castor you need?
Tell us what you're moving and we'll point you to the right wheel. Every GBL castor is backed by our Lifetime Warranty.
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