Caster wheel selection guide.
Most caster failures are selection failures — the right product family chosen with the wrong numbers. This guide walks the specification in the order that prevents them.
Specify in this order: (1) load per caster — total loaded weight divided by three, plus margin; (2) floor surface — it chooses tread material and diameter; (3) environment — heat, washdown, chemicals, outdoors choose fork and bearing materials; (4) mounting — plate or stem, matched to the frame; (5) configuration — swivel/rigid layout and brakes. Price enters only after all five are fixed.
Step 1: Load per caster — the number everything hangs on
Start with the equipment's total weight as loaded in service — including the load it carries, not its catalogue empty weight. Divide by three, not four: on any real floor, one caster of four is regularly unloaded or overloaded as the equipment crosses joints and uneven patches, and casters sized on a divide-by-four basis live their lives at the edge of their rating. Then add margin for shock: starting, stopping, thresholds and dock plates multiply static load briefly and repeatedly. Our load capacity guide works the maths with examples and explains why the test method behind a rating matters as much as the number.
Step 2: The floor chooses the tread
| Floor | Tread direction | Diameter direction |
|---|---|---|
| Smooth sealed concrete, epoxy | Polyurethane — load, quiet, floor protection | Standard for the load class |
| Cracked concrete, dock plates, yards | Rubber or larger PU — shock absorption | Larger: roll over, don't climb |
| Tile, delicate finishes | Soft PU or TPR, non-marking | Wider tread spreads the load |
| Hot floors, oven-adjacent | Phenolic (high temperature line) | Standard; heat sets the material |
| Wet / washdown floors | Non-marking tread on stainless construction | Standard; environment sets the fork |
| Gravel, broken ground | Pneumatic — the only real answer | Largest practical |
Step 3: Environment chooses the construction
Washdown and food environments push you to the stainless line and to sealed bearing arrangements. Heat pushes you to phenolic wheels and heat-specified grease. Outdoor duty pushes finish and bearing protection up the specification. Chemical exposure is the step buyers skip: tell your supplier the cleaning agents and process chemicals by name, because 'chemical resistant' without a named chemical is a wish, not a specification.
Step 4: Mounting matches the frame
Top plates for load and abuse tolerance; stems where the equipment provides sockets or threaded inserts. The interface dimensions — plate pattern or stem standard — are measured, not assumed. The measurement guide covers both, and the plate and stem pages explain where each wins.
Step 5: Layout and brakes
Two swivel + two rigid is the default equipment layout; all-swivel for tight-space manoeuvring; brakes where equipment parks on slopes, docks or in lifts — total-lock where it must not walk. The swivel vs rigid guide covers the layouts by equipment shape.
The step that is not a step: locking it
A selection becomes a specification when it is written down with the six locked variables — diameter, width, hardness, bearing, fork thickness, test method — and a sample is verified against it. That is the CASTOVELLA process on every line, and it is why the RFQ form asks for exactly the five steps above.
Related guides
Specification first. Price second.
Every guide on this site ends at the same place: a locked specification and a sample that proves it.