A pallet jack that has gotten hard to pull almost never has a hydraulic problem. It has worn wheels. Flat-spotted polyurethane and chunked load wheels multiply the effort required to move 4,000 pounds, and operators compensate by yanking, which is how backs get hurt.
Replacing them is a twenty-minute job. Ordering the correct ones is where people lose an afternoon, because Crown changed frame designs across production runs and the same model name does not guarantee the same wheel.
Key Takeaways
- Crown publishes the PTH 50 as a 5,000 lb capacity jack with 7-inch articulating steer wheels and “no-maintenance bushings and bearings sealed and lubricated for life.”
- Polyurethane for smooth indoor concrete: lower rolling resistance, quieter, non-marking. Nylon for debris, chemicals, moisture and dock ramps: tougher, but louder and it marks floors.
- Replace wheels once they have worn down about ¼ inch, or show cracking, chunking, or bearings that no longer spin freely.
- Check your serial number before ordering. Load wheel bore and mounting differ between PTH 50 frame generations even though the model name is unchanged.
What Wheels a Crown PTH 50 Actually Uses
Crown lists the PTH 50 at “Up to 5000 lb” capacity with “Up to 7.95 in” maximum lift and “7-inch articulating wheels,” plus “No-maintenance bushings and bearings sealed and lubricated for life” (Crown Equipment, retrieved 2026-07-28). Those articulating steer wheels are the reason a Crown crosses a dock plate without hanging up — they keep ground contact over uneven transitions.
Load wheels are the smaller pair at the fork tips. Industry sizing convention puts load wheels at roughly 3 inches or less in diameter and steer wheels at 7 to 8 inches, on a standard four-wheel layout of two steer and two load wheels — though some jacks add a second pair of load wheels for six total (Conger Industries, retrieved 2026-07-28).
A common aftermarket replacement load wheel for PTH 50 frames is a 3″ × 3.875″ wheel using 95A polyurethane over a cast iron core with bearings installed. Note the qualifier that comes with it on parts listings: it fits PTH 50 frames within specific serial number ranges.
Polyurethane or Nylon? Your Floor Decides
This is the only decision that genuinely changes day-to-day operation, and it is not about which material is better. It is about which failure mode you can tolerate.
Choose Polyurethane When
Your floors are smooth sealed concrete, indoors, and reasonably clean. Polyurethane has lower rolling resistance, so the same load is measurably easier to pull. It is quieter and non-marking, which matters in retail backrooms and any customer-facing space. The tradeoff is that polyurethane is susceptible to degradation from oil, water, and chemicals.
Choose Nylon When
You run over debris, through wash-down areas, across outdoor loading docks, or around chemicals. Nylon is tougher, resists chemical attack, and supports heavier point loads without deforming. In exchange it is harder to pull, noticeably louder, and more likely to mark floors. As one dealer guide puts it, for long runs on wet or rough surfaces polyurethane “may break down too quickly to be practical.”
| Factor | Polyurethane | Nylon |
|---|---|---|
| Pull effort | Lower | Higher |
| Noise | Quiet | Loud |
| Floor marking | Non-marking | Marks floors |
| Debris tolerance | Poor | Good |
| Oil, water, chemicals | Degrades | Resists |
| Best environment | Clean indoor concrete | Docks, wash-down, rough floors |
A practical middle path many operations land on: nylon load wheels, because they take the abuse at the fork tips, paired with polyurethane steer wheels, because that is where pull effort and noise are felt by the operator.
Durometer: What 95A Means
Polyurethane wheels are specified by Shore A hardness. A 95A wheel is firm — it resists deformation under load and rolls with less effort, but transmits more shock and grips less on smooth surfaces. Softer compounds in the 80s absorb floor imperfections and grip better, at the cost of higher rolling resistance and faster wear under sustained heavy loads.
For a 5,000 lb-rated jack on flat concrete, the harder end of the scale is the conventional choice, which is why 95A is what most PTH 50 replacement load wheels use.
When to Replace
Wheels need replacing once they have worn down about a quarter inch. Other signals are cracking, chunking — where pieces of the tread separate from the core — and wheels that no longer turn easily, which usually means a failed bearing rather than a worn tread.
Budget roughly $40–$55 per wheel, with nylon steer wheels near the top of that range and polyurethane load wheels around the middle. Replace in pairs. A new wheel running against a worn one on the opposite side puts the frame out of level and accelerates wear on both.
Before You Order: Check the Serial Number
This is the step that causes returns. Crown built the PTH 50 across multiple frame revisions, and load wheel bore diameter, axle size, and mounting hardware are not consistent across all of them. Parts suppliers list fitment by serial number range for exactly this reason.
Find the data plate on the jack, record the full model and serial, and match against the supplier’s fitment note. If you cannot read the plate, measure three things before ordering: overall wheel diameter, wheel width, and bore diameter through the hub.
Frequently Asked Questions
What size are Crown PTH 50 load wheels?
A widely stocked replacement is 3″ diameter × 3.875″ wide in 95A polyurethane over a cast iron core. Fitment is listed by serial number range, so verify against your data plate rather than the model name alone.
Are polyurethane or nylon wheels better for a pallet jack?
Neither is universally better. Polyurethane pulls easier, runs quieter and does not mark floors. Nylon survives debris, moisture and chemicals. Match the material to the floor you actually run on.
How often should pallet jack wheels be replaced?
There is no fixed interval — it depends on load, distance and floor condition. Inspect for roughly a quarter inch of wear, cracks, chunking, and bearings that do not spin freely.
Can I mix polyurethane and nylon wheels on one jack?
Yes, and pairing nylon load wheels with polyurethane steer wheels is a common compromise. Do not mix materials within the same pair, since different rolling resistance on left and right makes the jack track badly.
Why is my pallet jack suddenly hard to pull?
Most often flat-spotted or chunked load wheels, or a seized bearing. Check that all four wheels rotate freely by hand with the forks lowered before assuming a hydraulic fault.
The Bottom Line
Pick the material from your floor, not from a spec sheet ranking. Replace in pairs at about a quarter inch of wear. And verify fitment against the serial number on the data plate, because on the PTH 50 the model name alone does not tell you which wheel you need. Considering an electric walkie instead of a manual PTH 50? Our best electric pallet jack guide covers battery capacity and chemistry, the specs that matter most on a powered unit.
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