4x4 casters with 3-1/8" x 4-1/8" mounting plate — the dominant medium-duty industrial caster plate size. Fits most pre-fab work tables, equipment stands, and service carts designed for 4″ x 4″ mounting. 3″ to 5″ wheel sizes in polyurethane on polyolefin (multiple colors), solid polyurethane, phenolic, and thermo plastic rubber. 250 to 350 lb per caster. Stocked at our Mansfield, TX facility.
Same plate, multiple wheel options. Pick by wheel material and capacity. Plate dimensions interchange across the line.
| Wheel Size | Material | Color | Capacity | Best For |
|---|---|---|---|---|
| 3" x 1-1/4" | Poly on polyolefin | Gray / Blue / Red | 250 lb | Light commercial carts, prep tables |
| 3" Solid Poly | Solid polyurethane | Natural | 300 lb | Greasy floors, higher capacity |
| 3-1/2" x 1-1/4" | Poly on polyolefin | Gray / Blue | 275 lb | Light-medium carts |
| 4" x 1-1/4" | Poly on polyolefin | Gray / Blue / Red | 300 lb | Standard medium-duty industrial |
| 4" Phenolic | Phenolic resin | Brown | 350 lb | High-temp environments (autoclaves, oven trolleys) |
| 4" Solid Poly | Solid polyurethane | Natural | 350 lb | Highest capacity at 4" wheel size |
| 5" x 1-1/4" | Poly on polyolefin | Gray | 325 lb | Higher rolling efficiency |
| 5" TPR | Thermo plastic rubber | Gray (non-marking) | 315 lb | Quiet, non-marking on finished floors |
3-1/8" x 4-1/8" is the dominant medium-duty plate size in U.S. industrial work tables and equipment stands. Often referred to as "4x4 plate" or "4 by 4 caster" plate. Measure your cart's top plate bolt-hole-to-bolt-hole center-to-center to confirm before ordering.
3" handles 250 lb per caster on smooth concrete. 4" handles 300-350 lb and bridges floor seams better. 5" handles 315-325 lb and rolls fastest with least operator effort. Bigger wheel = easier roll but higher cart height.
Polyurethane on polyolefin: non-marking, quiet, easy roll — the workhorse. Solid polyurethane: greasy floors, higher capacity. Phenolic: high-temperature (autoclave, oven). TPR: quietest, non-marking on finished commercial flooring.
Gray TPR/poly: non-marking, food-service standard. Blue poly: visual identification for medical or color-coded plant zones. Red poly: visual identification for hot or restricted zones. The color doesn't affect performance — it's a visual marker.
The dimensions of the caster's top mounting plate. 3-1/8" wide by 4-1/8" long, with four bolt holes for mounting bolts. This is the U.S. industry-dominant medium-duty plate size, often called "4x4 plate" or "4 by 4 caster" colloquially. Fits standard medium-duty industrial work tables, equipment stands, and service carts.
Yes — "4x4 caster" is the common shorthand. The actual plate dimensions are 3-1/8" x 4-1/8", but the bolt-hole-to-bolt-hole layout sits within a 4" x 4" rectangle — hence "4x4". When someone asks for a "4 by 4 caster", this is the plate size they mean.
250-350 lb per caster depending on wheel material. A 4-caster cart with 300 lb single-caster casters carries 1,200 lb total with full capacity safety. For heavier carts, step up to a heavier plate size (4" x 4-1/2") and matching higher-capacity casters.
Poly on polyolefin: thin polyurethane tread bonded to a polyolefin (plastic) hub — lighter, lower cost, 250-325 lb capacity. Solid polyurethane: single-piece polyurethane wheel — heavier, higher cost, 300-350 lb capacity. Pick solid poly for greasy floors and higher loads; pick poly-on-polyolefin for standard service.
Gray polyurethane on polyolefin: non-marking. Gray TPR: non-marking, food-service standard. Solid polyurethane (natural): non-marking. Phenolic (brown): can mark light flooring under heavy load — use only in high-temp environments where flooring is concrete or industrial tile.
Close but not exact. 100mm x 100mm metric plates have a slightly different bolt pattern than 3-1/8" x 4-1/8" U.S. plates. The 1/8" difference means mounting bolts don't align. Measure your bolt-hole-to-bolt-hole center distances before ordering — if your equipment is imported from Europe or Asia, you may need a metric plate caster.
3-1/8" x 4-1/8" plates use 4 bolt holes in a rectangle 2-3/8" x 3-3/8" center-to-center. Bolt holes accommodate 3/8" or 5/16" mounting bolts. The same bolt pattern is standard across all major U.S. caster manufacturers (Hamilton, Albion, Colson, DuraStar).
Yes if your equipment uses 3-1/8" x 4-1/8" plates with the standard bolt pattern. Most pre-fab medium-duty industrial carts and equipment stands do. Measure first; bolt-hole alignment matters more than the plate footprint itself.
