Commonly Sold as "SET 4"

LM29749 / LM29710

The Universal Standard for 3,500 lbs Trailer Axles & Utility Hubs.

Dimensional Specifications Unit: Imperial (Inch)
Cone Part NumberLM29749
Cup Part NumberLM29710
Bore Diameter (d)1.5000 in (38.100 mm)
Outer Diameter (D)2.5625 in (65.088 mm)
Assembly Width (T)0.7100 in (18.034 mm)
Cone Width (B)0.7200 in (18.288 mm)
Cup Width (C)0.5300 in (13.462 mm)
Axle Rating Compatibility3,500 lbs (Inner Bearing)
Dynamic Load Rating12,500 lbs (55.6 kN)

The Essential Trailer Wheel Bearing

If you own a boat trailer, utility trailer, or camper, chances are you are riding on the LM29749-LM29710 bearing set. Commonly marketed in auto parts stores as "SET 4", this tapered roller bearing is the inner bearing standard for 3,500 lb axle hubs (usually paired with the L68149 outer bearing). Its 1.500-inch bore is machined to fit precisely over the spindle spindle step, carrying the majority of the load during transit.

Durability in Marine Environments

One of the biggest challenges for the LM29749/10 series is environmental exposure. Boat trailers are submerged in water repeatedly. While the steel quality of Timken bearings is superior, longevity in these conditions depends heavily on the seal and grease quality. We recommend pairing this bearing with a double-lip grease seal and using a marine-grade calcium sulfonate grease. Unlike the sealed SKF Explorer series used in industrial motors, trailer bearings require regular repack maintenance.

Installation Guide: Preload is Key

Improper installation is the #1 cause of trailer bearing failure. The LM29749 cone must be seated fully against the spindle shoulder. When tightening the castle nut, the goal is to remove endplay without creating excessive preload drag.

  • Step 1: Tighten nut while spinning the hub to seat the rollers.
  • Step 2: Back off the nut until loose.
  • Step 3: Finger tighten only, and insert the cotter pin.

Comparing this to the automotive LM67000 series or the heavy-duty LM300849, the tolerance for preload on trailer spindles is much more forgiving, but "too tight" will still burn up a hub in under 50 miles.

Why Choose Timken over Generic?

In the trailer market, cheap "white box" bearings are rampant. These generic bearings often suffer from poor heat treatment, leading to spalling (flaking) of the raceways. The LM29749 supplied by E-MARC comes from our verified factory supply chain, ensuring that the case-carburized steel can withstand the shock loads of potholes and curbs—something cheaper through-hardened steel cannot do.

Common Questions

Is this the Inner or Outer bearing?

On a standard 3,500 lb axle (5-lug hub), the LM29749/10 (1.500" ID) is the Inner bearing. The Outer bearing is typically L68149/11 (1.378" ID).

Does this fit Dexter axles?

Yes, it is the standard fitment for Dexter, AL-KO, and Lippert 3.5k axles.