At a Glance

> Increased Bearing Life: Uses the larger #02475 outer bearing for better load distribution.
> Shear Strength: 5/8" studs provide superior clamping force compared to 1/2" alternatives.
> Standard Compatibility: Fits common 12-1/4" electric or hydraulic brakes.
> Wheel Pilot Hole: These hubs require a 4.75" hub-centric pilot hole on the rim.
> Stud Size: Ensure your wheels can accept 5/8" studs; standard 7K wheels are often bored only for 1/2" studs.
Brand: R and P Carriages
SKU: 99-865-58HD-KIT

Before You Order

Match the part number, measurements and connection points that apply to your trailer.

Bearings	Match inner and outer bearing numbers.
Seal	Match the seal number or dimensions.
Bolt Pattern	Verify the complete lug pattern.
Brake Size	Confirm when applicable.

Product Details

Trailer Braking Axle / Hub & Drum System

Heavy Duty 7K to 8K Hybrid Trailer Hub Drum 8x6.5 5/8 Studs Upgrade Complete Kit

Upgrade your 7,000 lb axle with 8,000 lb capacity bearings and heavy-duty 5/8" studs for maximum durability and service life.

Part Number: 99-865-58HD-KIT 8 on 6.5" Bolt Pattern 7K to 8K Hybrid Upgrade

Overview

This Hybrid Hub & Drum is the ultimate solution for standard 7,000 lb trailer axles. While it is cast to fit standard 12-1/4" trailer brakes, it is precision-machined to accept larger 8,000 lb capacity bearing sets and robust 5/8" wheel studs. This kit provides a significant strength advantage over standard 7K hubs that typically use 1/2" studs and smaller outer bearings, making it a favorite for high-demand equipment haulers and dump trailers.

R&P Service Insight

Why the Hybrid design matters for commercial and heavy-duty towing:

Increased Bearing Life: Uses the larger #02475 outer bearing for better load distribution.
Shear Strength: 5/8" studs provide superior clamping force compared to 1/2" alternatives.
Standard Compatibility: Fits common 12-1/4" electric or hydraulic brakes.

R&P Knowledge Hub

Compatibility: Designed for 7,000 lb and 8,000 lb capacity trailer axles.

Vehicle / System Fit: Common on Kaufman, Sure-Trac, and Lippert/LCI heavy-duty trailer brands.

Installation Notes: Verify your spindle sizes match the #25580 inner and #02475 outer bearings before ordering.

Performance Insight: The use of 8K internals on a 7K-size drum offers a higher safety margin for heavy-duty commercial towing applications.

Brand & Fitment Note

Selling Brand: R&P Carriages / Verified Aftermarket Upgrade Kit

Application Reference: Any OEM or platform names in this listing (such as Lippert, Kaufman, or Sure-Trac) describe compatibility, fitment target, or application style only where supported by verified dimensions.

What This Means: This listing is for a curated R&P heavy-duty upgrade kit, designed as a high-performance replacement for standard-spec 7K components.

Before Ordering: Verify wheel pilot hole (4.75"), stud clearance (5/8"), and spindle seal surface (2.25") before installation.

R&P Repair Insight

Before ordering, please perform these three critical checks to ensure a perfect fit for your trailer:

Wheel Pilot Hole: These hubs require a 4.75" hub-centric pilot hole on the rim.
Stud Size: Ensure your wheels can accept 5/8" studs; standard 7K wheels are often bored only for 1/2" studs.
Seal Surface: Confirm your spindle's seal seat is compatible with the 2.25" ID grease seal (10-63).

Features

High-Strength Casting

Heavy-duty cast iron construction with pre-pressed races for immediate installation.

Premium Bearings

Includes #25580 inner and #02475 outer bearings for increased load endurance.

Double-Lip Seal

Equipped with a 10-63 grease seal to keep contaminants out and lubrication in.

5/8" Stud Upgrade

Larger 5/8"-18 studs provide superior wheel retention for heavy-duty hauling.

Specifications

Specification	Detail
Part Number	99-865-58HD-KIT
Bolt Pattern	8 on 6.5"
Axle Rating	7,000 - 8,000 lbs
Drum Size	12-1/4" x 2-1/2"
Stud Diameter	5/8"-18
Inner Bearing	#25580 (1.75" ID)
Outer Bearing	#02475 (1.25" ID)
Grease Seal	10-63 (2.25" ID)

Fitment / Application

Category	Details
System	Trailer Braking Axle
Primary Fit	7K - 8K Spindles
Brake Match	12-1/4" Assemblies
Notes	Must verify wheel pilot hole (4.75") and stud clearance.

Included Components

Quantity	Item
8	006-058-00 — 5/8"-18 flange wheel lug nut
1	010-045-00 — O-ring, 2.609" I.D. x .139
1	046-032-00 — Oil cap center plug
1	10-225-15 — Oil seal, 2.25" x 3.38"
1	21-35 — Dexter oil cap, 2.875"-12
1	2475 — Outer bearing, 1.25" I.D.
1	25580 — Inner bearing, 1.75" I.D.
1	99-865-58HD — Hybrid hub drum, 8000#, 8 x 6.5", 5/8" stud

FINAL VERIFICATION: Verify all bearing numbers, spindle seal surface diameter, and wheel stud/pilot hole measurements before installation. Hybrid hubs require specific wheel specifications (5/8" stud holes and 4.75" pilot). OEM or platform references in this listing describe application fitment only unless the product is specifically identified as OEM and verified.

SHOP MATCHING 7K-8K AXLE PARTS

Heavy Duty 7K to 8K Hybrid Trailer Hub Drum 8x6.5 5/8 Studs Upgrade Complete Kit (99-865-58HD-KIT)