Wheel Load Capacity: How to Calculate Correctly

Choosing the right load capacity is the single most critical factor when buying wheels. A wheel that cannot handle the load of its application fails prematurely, creates safety hazards, and drives up replacement costs. This guide walks you through the calculation step by step, explains when you need 100 kg, 200 kg, 500 kg, or 1000 kg capacity wheels, and when heavy-duty high-capacity wheels are required.

The Basic Calculation Formula

The formula for minimum capacity per wheel is:

Capacity per wheel = (Total weight / Number of wheels) × Safety factor

This straightforward formula contains several details worth understanding before you select.

Example 1 — Warehouse trolley

• Empty trolley weight: 40 kg
• Maximum load: 260 kg
• Total weight: 300 kg
• Number of wheels: 4
• Safety factor: 1.4

Capacity per wheel = (300 / 4) × 1.4 = 75 × 1.4 = 105 kg

You therefore need at least 125 kg capacity wheels (the next standard value above 105 kg).

Example 2 — Heavy-duty industrial cart

• Cart weight: 120 kg
• Maximum load: 1,500 kg
• Total weight: 1,620 kg
• Number of wheels: 4 (2 fixed + 2 swivel)
• Safety factor: 1.5 (dynamic environment)

Capacity per wheel = (1,620 / 4) × 1.5 = 405 × 1.5 = 607.5 kg

You therefore need 700 kg capacity wheels, or even 1000 kg if floor irregularities are present.

Safety Factors: When to Use Each

The safety factor is not arbitrary — it depends on operating conditions:

| Conditions | Safety factor | |---|---| | Smooth floor, slow movement | 1.3× | | Typical industrial conditions | 1.5× | | Vibration, uneven floor | 1.7× | | Shock loading, ramps | 2.0× | | Extreme conditions (metallurgy, etc.) | 2.5× |

Important: Wheels for heavy loads in dynamic applications (lifting equipment, factory vehicles) must always carry a safety factor of at least 1.7×.

Static vs Dynamic Loads

Manufacturers typically publish two capacity values for each wheel:

• Static load: The maximum load the wheel can bear when stationary. This is always the higher figure.
• Dynamic load: The maximum load under movement. This is the value you use for calculations.

A wheel rated 500 kg dynamic can bear 800–1,000 kg statically. If your equipment remains stationary for long periods, you may reference the static load for that specific scenario — but only for that scenario.

Uneven Load Distribution

In practice, load is not shared equally across all wheels. On a four-wheeled cart:

• Front wheels (swivel) typically bear 60–65% of the load during turns.
• The wheel on the inside of a turn receives a disproportionately higher load.
• On inclined surfaces, wheels on the lower side can bear up to 80% of the total weight.

As a rule: in applications with frequent turns or uneven floors, increase the safety factor by 0.2–0.3 or select the next higher capacity class.

Effect of Speed

Movement speed significantly affects the working capacity of a wheel:

• Up to 4 km/h (manual movement): Use the rated capacity.
• 4–8 km/h (electric pallet trucks, small AGVs): Reduce effective capacity by 20%.
• 8–15 km/h (industrial vehicles): Reduce effective capacity by 35–40%.

Example: A 500 kg wheel in a 10 km/h application has a practical working capacity of approximately 300 kg.

Effect of Temperature

Wheel materials change properties with temperature:

• Polyurethane: Full capacity up to 60 °C. At 80 °C loses 25–30% of capacity.
• Nylon: Stable up to 80 °C, minor reduction up to 100 °C.
• Rubber: Capacity decreases above 50 °C.
• Cast iron: Maintains full capacity up to 300 °C and beyond.

If you operate in a hot environment, apply a temperature derating factor or select a material suited for high temperatures.

Effect of Floor Condition

The type of flooring affects both effective load capacity and rolling resistance:

• Smooth concrete / epoxy: Rated capacity, low resistance.
• Gravel / rough concrete: Increase the factor by 0.2–0.3.
• Metal grating: Significant stress on small wheels. Use a minimum diameter of 125 mm.
• Floor cracks / expansion joints: Act as impact loads — increase the factor.

Complete Calculation Example

Scenario: Heavy cart in a cold-storage warehouse (–10 °C), concrete with expansion joints, electric traction at 6 km/h.

1. Equipment weight: 200 kg
2. Load: 1,000 kg
3. Total: 1,200 kg
4. Wheels: 4
5. Weight per wheel: 1,200 / 4 = 300 kg
6. Speed factor (6 km/h): ÷ 0.80 → 375 kg
7. Floor factor (joints): × 1.25 → 469 kg
8. General safety factor: × 1.4 → 656 kg

Selection: 700 kg capacity wheels in special low-temperature polyurethane.

Conclusion

Correct load capacity calculation is not merely a technical requirement — it is an investment in the safety and longevity of your equipment. High-capacity wheels selected according to real operating conditions last for years, while undersized wheels fail in months.

Browse our catalog to find wheels rated from 50 kg to 3,000 kg per unit. For complex applications or heavy loads, contact the GM Rodes technical team — we help you choose correctly the first time.