5,200 lb & 6,000 lb Trailer Axles – Parts & Identification Guide
The 5.2K (5,200 lb) and 6K (6,000 lb) axles are commonly found on medium-duty utility trailers, enclosed trailers, landscape trailers, small equipment trailers, and light commercial hauling applications. These axles are a step up from standard 3.5K and 4.4K setups, offering increased load capacity while still maintaining relatively simple serviceability.
Although they are often grouped together, 5.2K and 6K axles can use different brake, hub, and bearing configurations depending on the manufacturer (Dexter, Lippert, and others). Because of this, it is important to verify measurements and part numbers before ordering replacements.
1. Bearings
Most 5.2K and 6K axles commonly use one of the following bearing sets:
- Inner Bearing: 25580
- Outer Bearing: 15123 or 25520 (varies by axle design)
These tapered roller bearings are designed to handle moderate-heavy loads and highway use.
Regular greasing, inspection, and correct preload are critical to preventing overheating and premature wear.
2. Grease Seal
A very common grease seal used on many 5.2K and 6K axles is:
-
10-36 Grease Seal
- 2.125" inner diameter (varies slightly by spindle)
- 3.376" outer diameter
⚠️ Always confirm seal size by spindle or old seal number before ordering.
3. Hub & Drum Assemblies
Most 5.2K and 6K axles use:
- 6 on 5.5 bolt pattern (most common)
- Heavy-duty hub & drum assemblies
- Grease-packed bearing systems
However, configurations can vary depending on manufacturer and brake size.
4. Brake Configurations
5,200 lb Axles (5.2K)
Most 5.2K axles commonly use:
- 10" x 2¼" electric brake assemblies
These setups are often found on:
- Utility trailers
- Light equipment trailers
- Enclosed cargo trailers
They provide reliable stopping power for moderate loads and are typically paired with 6-lug hub/drums.
6,000 lb Axles (6K)
Most 6K axles commonly use:
- 12" x 2" electric brake assemblies
These heavier-duty brakes provide:
- Increased braking surface
- Better heat dissipation
- Improved performance under heavier loads
6K axles are more commonly used on:
- Equipment trailers
- Car haulers
- Medium-duty commercial trailers
5. Hub & Drum Variations
Depending on axle setup, common hub/drum options include:
- 10" x 2¼" hub/drums (typical 5.2K)
- 12" x 2" hub/drums (typical 6K)
This is why confirming brake size and hub stamping is critical before ordering parts.
6. Caps & Dust Covers
5.2K and 6K axles may include:
- Standard grease caps
- EZ Lube grease caps (grease zerk spindle)
- Rubber plug caps (less common on higher-duty setups)
Proper cap selection helps maintain bearing protection and grease retention.
7. Suspension Components
Most trailers using 5.2K and 6K axles include:
- Heavy-duty leaf springs (typically 2" or 2½" wide)
- Equalizers (tandem axle setups)
- U-bolt kits
- Shackle straps and bolts
- Bronze bushings or wet bolt kits (on upgraded setups)
Worn suspension components can cause axle misalignment, uneven tire wear, and poor towing stability.
8. Spindle Type
Spindle design varies between manufacturers, but most 5.2K and 6K axles use heavy-duty spindles that determine:
- Bearing compatibility
- Seal size
- Hub/drum fitment
- Brake assembly size
Bearing numbers are the most reliable way to confirm correct parts.
Common Replacement Wear Items
The most commonly replaced parts on 5.2K and 6K axles include:
✔ Bearings & races
✔ Grease seals
✔ Brake assemblies
✔ Hub/drums
✔ Magnets
✔ Dust caps / grease caps
✔ Suspension hardware
Always Verify Before Ordering
Because 5.2K and 6K axles can vary widely between manufacturers, always confirm:
- Brake size (10" x 2¼" or 12" x 2")
- Bearing numbers
- Seal size
- Hub type (EZ Lube or standard)
- Bolt pattern (commonly 6 on 5.5)
- Axle tag information
Even small differences can affect fitment and safety.
At Highway Trailer Company, we carry a full range of 5.2K and 6K axle components including bearings, seals, hub/drums, brake assemblies, and suspension parts to keep your trailer operating safely and reliably.