Comprehensive trailer wheel bearing size chart showing common bearing numbers and dimensions

Essential Trailer Wheel Bearing Chart for Every Owner

Essential Trailer Wheel Bearing Chart for Every Owner

You need to replace a trailer wheel bearing. You pull the hub, look at the old bearing, and find a number stamped on it — or maybe you don't. Now what?

This page is the reference you'll bookmark. We've compiled the most common trailer wheel bearing sizes organized by axle weight rating, along with seal sizes, grease specs, and identification tips. Whether you're ordering parts or just figuring out what's in your hubs, this chart has you covered.

Trailer Wheel Bearing Chart by Axle Weight Rating

The bearings in your trailer hubs are determined by the axle's weight rating, not your trailer's total weight. A tandem axle trailer rated at 7,000 lbs GVWR uses two 3,500 lb axles — so you'd look at the 3,500 lb row below.

2,000 lb Axle

Position Bearing Number Race (Cup) Number Inner Diameter Outer Diameter
Inner (rear) L44649 L44610 1.0625" 1.9800"
Outer (front) L44649 L44610 1.0625" 1.9800"

Seal: 1.249" ID × 1.983" OD (Grease seal #10-19)
Spindle: 1" straight
Notes: Same bearing inner and outer. Common on small utility trailers, lightweight boat trailers, and jet ski trailers. The L44649/L44610 is one of the most widely available bearings — every auto parts store stocks them.

3,500 lb Axle

Position Bearing Number Race (Cup) Number Inner Diameter Outer Diameter
Inner (rear) L68149 L68111 1.3775" 2.3280"
Outer (front) L44649 L44610 1.0625" 1.9800"

Seal: 1.719" ID × 2.565" OD (Grease seal #10-36)
Spindle: 1-1/16" to 1-3/8" stepped (EZ Lube style common)
Notes: The most common trailer axle in America. Found on most single-axle utility trailers, mid-size boat trailers, and light cargo trailers. If you have a trailer and don't know the axle weight, there's a good chance it's a 3,500 lb with this bearing combination.

5,200 lb Axle

Position Bearing Number Race (Cup) Number Inner Diameter Outer Diameter
Inner (rear) 25580 25520 1.7500" 3.2650"
Outer (front) 15123 15245 1.2500" 2.4410"

Seal: 2.125" ID × 3.376" OD (Grease seal #10-60)
Spindle: 1-3/4" to 1-1/4" stepped
Notes: Common on car haulers, larger boat trailers, and medium-duty equipment trailers. The step up from 3,500 lb to 5,200 lb is significant — larger bearings, beefier spindles, and more grease capacity.

6,000 lb Axle

Position Bearing Number Race (Cup) Number Inner Diameter Outer Diameter
Inner (rear) 25580 25520 1.7500" 3.2650"
Outer (front) 15123 15245 1.2500" 2.4410"

Seal: 2.125" ID × 3.376" OD (Grease seal #10-60)
Spindle: 1-3/4" to 1-1/4" stepped
Notes: Same bearing combination as the 5,200 lb axle in most configurations. The 6,000 lb axle typically uses heavier springs and a beefier tube, but the spindle and bearings are often identical. Common on horse trailers, larger enclosed trailers, and heavy equipment haulers.

7,000 lb Axle

Position Bearing Number Race (Cup) Number Inner Diameter Outer Diameter
Inner (rear) 14125A 14276 1.2500" 2.7170"
Outer (front) 25580 25520 1.7500" 3.2650"

Seal: 2.250" ID × 3.376" OD
Spindle: 2-1/4" to 1-3/4" stepped
Notes: Found on heavy tandem-axle trailers, large car haulers, and gooseneck flatbeds. Some 7,000 lb axles use different bearing configurations depending on the manufacturer — always verify by measuring your spindle or checking the existing bearing numbers.

8,000 lb Axle

Position Bearing Number Race (Cup) Number Inner Diameter Outer Diameter
Inner (rear) HM218248 HM218210 3.5430" 5.7870"
Outer (front) 25580 25520 1.7500" 3.2650"

Seal: Varies by manufacturer — measure existing seal
Spindle: Varies — typically unitized hub or large stepped spindle
Notes: Heavy-duty territory. Found on large gooseneck trailers, heavy equipment haulers, and commercial-grade flatbeds. At this capacity, you may encounter unitized hub assemblies (non-serviceable bearings that are replaced as a unit) rather than traditional tapered roller bearings. Always verify the configuration before ordering parts.

How to Identify Your Bearing Size

Three ways to figure out what bearings your trailer uses, ranked from easiest to most involved:

Method 1: Check the Axle Rating Sticker

Most trailer axles have a capacity sticker on the axle tube or on the trailer's VIN plate. Find the per-axle rating and match it to the chart above. This works about 80% of the time — the other 20% are non-standard or custom configurations.

Method 2: Read the Bearing Number

If you've already pulled the hub, look at the bearing itself. The part number is stamped on the cone (the inner part with the rollers). It's usually on the small end face or the side of the cone. Common numbers you'll see:

  • L44649 — 2,000 lb and 3,500 lb outer
  • L68149 — 3,500 lb inner
  • 25580 — 5,200 lb and 6,000 lb inner, 7,000 lb and 8,000 lb outer
  • 15123 — 5,200 lb and 6,000 lb outer

The number on the bearing tells you exactly what to order for replacement — including the matching race.

Method 3: Measure the Spindle

If there's no sticker and no readable number on the bearing, measure the spindle diameter where the inner bearing sits (the larger step) and where the outer bearing sits (the smaller step). Match those measurements to standard spindle sizes:

Inner Step Outer Step Typical Axle Rating
1.000" 1.000" 2,000 lb
1.375" 1.0625" 3,500 lb
1.750" 1.250" 5,200-6,000 lb
2.250" 1.750" 7,000 lb

Use a caliper for accurate measurement — a tape measure isn't precise enough for bearing identification.

Bearing Replacement Kit: What You Need

When you order replacement bearings, make sure you get the complete kit. Here's the shopping list for each hub:

  • Inner bearing cone and rollers (the part that spins)
  • Inner bearing race/cup (the part that presses into the hub)
  • Outer bearing cone and rollers
  • Outer bearing race/cup
  • Grease seal (always replace the seal — they're cheap and critical)
  • Cotter pin (never reuse cotter pins)
  • Dust cap (replace if dented or doesn't seat properly)

Most trailer parts suppliers sell these as complete kits for $20-50 depending on the axle rating. Buying the kit is easier and cheaper than sourcing individual components.

Grease Types and Quantities

Not all grease is created equal, and using the wrong type can damage your bearings.

Protect your trailer

Recommended Grease Types

Application Grease Type NLGI Grade
Standard trailer (road use) Lithium complex #2
Boat trailer (water exposure) Marine-grade (lithium complex or aluminum complex) #2
High-temperature application Synthetic or polyurea #2

Critical Rules for Grease

  • Never mix grease types. Incompatible greases (e.g., lithium + polyurea) can thin out and lose all protective properties. If you're switching grease types, clean everything completely first.
  • Don't over-pack. Fill the bearing completely, but the hub cavity should only be 1/3 to 1/2 full. Too much grease causes churning, which generates heat. The grease in the hub cavity is a reservoir, not a bath.
  • Pack properly. Force grease through the bearing from the large end until it comes out between each roller on the small end. Every space between every roller should be filled. A bearing packer tool ($15-25) makes this faster and more consistent than doing it by hand.
  • Use fresh grease. Grease degrades over time, even in the tube. If your grease tube has been sitting in the garage for five years, buy new.

How Much Grease Per Bearing

Approximate grease quantities by axle size:

Axle Rating Per Bearing (approx.) Hub Cavity
2,000 lb 1-2 oz 2-3 oz (1/3 full)
3,500 lb 2-3 oz 3-4 oz (1/3 full)
5,200-6,000 lb 3-4 oz 4-6 oz (1/3 full)
7,000-8,000 lb 4-6 oz 6-8 oz (1/3 full)

When to Replace vs. When to Repack

Bearing replacement and repacking follow different schedules:

Repack Schedule

  • Every 12,000 miles or annually — whichever comes first
  • After every submersion (boat trailers at the ramp)
  • After extended storage (6+ months)
  • Whenever you pull the hub for brake work

Replace When

  • Any visible damage — pitting, spalling, scoring, discoloration
  • Rough or gritty feel when rotated by hand
  • Evidence of overheating (blue/brown tint on metal)
  • Water contamination (milky or rust-colored grease)
  • Excessive play that can't be corrected by adjustment
  • Unknown maintenance history (start fresh)
  • Any signs of bearing failure

Always replace bearings in sets (inner + outer on the same side), and always replace the races at the same time. A new bearing in an old, worn race will wear out rapidly.

Tools You'll Need for a Bearing Job

If you maintain your own trailer, here's the tool list for a bearing repack or replacement:

  • Jack and jack stands
  • Wheel chocks
  • Channel-lock pliers (for dust cap removal)
  • Needle-nose pliers (for cotter pin)
  • Socket set (for castle nut)
  • Seal puller or flat-head screwdriver (for grease seal)
  • Bearing packer tool (recommended) or plenty of patience
  • Race driver set or appropriate punch (for race replacement)
  • Clean rags and solvent for cleaning
  • NLGI #2 wheel bearing grease
  • Torque wrench (optional but recommended)
  • Dial indicator (optional — for precise end play measurement)

Total investment for the tool set (if starting from scratch): $50-100. You'll use all of it again next year.

How Temperature Monitoring Extends Bearing Life

The charts and schedules above tell you when to service bearings on a calendar. But bearing failure doesn't follow a calendar — it follows conditions. Water intrusion, overloading, a loose castle nut, contaminated grease — any of these can put a bearing on the failure path well before the next scheduled service.

Continuous axle temperature monitoring catches these off-schedule failures by detecting the first sign of trouble: heat. A bearing running 20°F hotter than its partner on the other side is telling you something — long before it makes noise, long before you feel wobble, long before the hub starts smoking.

TrailerWatchdog TWD-1500 monitoring system for real-time axle and tire monitoring

Related Reading

🛡️ Protect Your Trailer with Smart Monitoring

You've got the right bearings in the right hubs. Now make sure they stay healthy between service intervals. The TWD Adventure combines TPMS and axle temperature monitoring — detecting bearing heat before you can feel it, and alerting you before a small issue becomes a roadside disaster.

Learn More →

Frequently Asked Questions

Are trailer bearings the same as automotive wheel bearings?

Trailer axles use tapered roller bearings — the same type found in many older vehicles and truck axles. However, the sizes are different. You can't use a bearing from your car on your trailer (or vice versa). Always match by bearing number or spindle measurement, not by eyeballing it.

Can I use bearings from a different manufacturer?

Yes, as long as the bearing number matches. The numbering system (L44649, 25580, etc.) is an industry standard — a Timken L44649 is dimensionally identical to an SKF L44649 or a National L44649. Quality may vary between brands, but dimensions are standardized.

What if my bearing number doesn't match anything in the chart?

Some trailer manufacturers use non-standard or proprietary hub and spindle configurations. If your bearing number doesn't match common trailer bearings, check with the trailer or axle manufacturer. You can also cross-reference the number on any bearing supplier's website to find the exact dimensions and matching race.

Do I need to replace the races when I replace the bearings?

Yes. Always. The bearing and race wear together as a matched set. A new bearing in a worn race will wear out faster, run hotter, and may not maintain proper clearance. Races are included in most bearing kits and cost very little on their own ($5-10 each).

How do I remove old races from the hub?

The race press-fits into the hub bore. To remove it, flip the hub over and use a brass punch or race driver to tap it out from the back side, alternating around the circumference to walk it out evenly. Don't use a steel punch on a steel race — you'll damage the hub bore. New races get installed the same way in reverse, tapping them in squarely until they seat flush against the hub shoulder.

What about EZ Lube spindles?

EZ Lube (or similar) spindles have a grease fitting on the end that lets you add grease without pulling the hub. This is convenient for topping off between services, but it does not replace a full repack. Over time, old grease accumulates and can trap contaminants. Full disassembly, cleaning, and repacking is still necessary at regular intervals.

Are there bearing alternatives for boat trailers?

Some boat trailer owners upgrade to oil bath hubs, which submerge the bearings in oil rather than packing them with grease. Oil bath hubs offer better lubrication consistency and are more forgiving of occasional submersion, but they require checking the oil level before each trip and replacing the oil on the same interval as a grease repack. They're a good upgrade if you launch frequently.

Can I use this chart for travel trailer or RV axles?

Yes, for standard Dexter, Lippert, or similar axles used in travel trailers and RVs. Match by axle weight rating. However, some larger RVs use unitized hub assemblies or other configurations. Check your owner's manual or the axle manufacturer's specs if you have a larger Class A or fifth wheel.