How to Choose the Right Wheel Bearings for your trailer
Wheel bearings are one of the most overlooked parts on a trailer — until they fail. A seized bearing on the side of the road (or worse, a wheel separating at speed) is an expensive and dangerous situation that's almost always preventable. The good news is that checking, identifying and replacing trailer bearings is well within reach for any DIY owner.
This guide walks you through how to check your bearings, how to identify the right replacement, and which Trojan bearing kits suit common NZ trailers.
How to Check Your Trailer Wheel Bearings
Get into the habit of checking bearings before every long trip and at least every 12 months. For boat trailers, check before first use for the summer, or during winter when doing maintenance — salt water and bearing grease don't mix well, and water ingress is the number one cause of premature bearing failure on boat trailers.
What you'll need: A jack, jack stands, and five minutes per wheel.
Step 1 — Check for play
Jack up the trailer so the wheel is off the ground. Grip the tyre at the 3 o'clock and 9 o'clock positions and try to rock it side to side. Then grip at 12 and 6 and rock again. Any noticeable movement (play) indicates worn bearings or a loose nut — both need attention before you tow.
Step 2 — Spin the wheel
With the wheel off the ground, spin it by hand. It should rotate smoothly and quietly. Grinding, rumbling, or a rough feel means the bearing surfaces are worn or pitted. A slight drag is normal (brake shoes or disc pads), but noise is not.
Step 3 — Check for heat after towing
After a short run, carefully touch the hub (not the disc or drum — these get hot from braking). A warm hub is fine. A hub you can't hold your hand against is a warning sign — the bearing is running dry or failing.
Special note for boat trailers: Water washes out grease every time you submerge the hubs. If you're regularly launching, consider re-packing bearings annually or upgrading to a bearing kit with a fitted seal attachment. Using a quality marine grease is essential — standard grease emulsifies in water.
Special note for heavy-load trailers: If you're towing near your trailer's rated capacity — loaded car trailers, plant trailers, farm trailers — bearings work harder and wear faster. Check more frequently and don't defer replacement if you see any of the warning signs above.
Identifying Your Trailer Bearings
Trailer wheel bearings use a standardised numbering system, so once you know the numbers stamped on your existing bearings you can match replacements exactly. Most NZ trailers use tapered roller bearings in a cup-and-cone configuration — an outer bearing (smaller) and an inner bearing (larger), each made up of a cup (the outer race) and a cone (the inner race with rollers).
Where to find the numbers:
Remove the hub and pull the bearing out. The part number is stamped on the side of the cone (the part with the rollers). Common examples you'll see on NZ trailers:
- LM11949 / LM11910 — outer cone/cup, very common on 1500kg trailers
- LM67048 / LM67010 — inner cone/cup, standard on 1500kg trailers
- LM68149 / LM68110 — inner cone/cup, common on 1750kg trailers
- LM48548 / LM48510 — inner cone/cup, standard on 2000kg trailers
The numbers in brackets on Trojan kits indicate the bearing dimensions in millimetres (bore x outer diameter), which can help cross-reference if the stamped number is worn or unclear.
If you can't read the number, measure the shaft diameter where the bearing sits — this will match the bore size and narrow down your options considerably.
Choosing the Right Trojan Bearing Kit
Rather than buying cups, cones and seals separately, Trojan bearing kits bundle everything you need for one hub in a single part number. Trojan is one of the most widely used trailer bearing brands in New Zealand, with kits covering the most common trailer configurations.
| Kit | Rating | Outer Cup | Outer Cone | Inner Cup | Inner Cone | Seal |
|---|---|---|---|---|---|---|
| PT1184 | 1500kg | LM11910 | LM11949 (19x45) | LM67010 | LM67048 (32x59) | PT1013 |
| PT1186 | 1750kg | LM12710 | LM12749 (22x45) | LM68110 | LM68149 (35x59) | PR6692 |
| PT1129 | 2000kg | LM44610 | LM44649 (27x50) | LM48510 | LM48548 (35x65) | PT1014 |
The Right Grease Makes a Difference
Don't use whatever grease is on the workshop shelf. Standard lithium grease washes out in water and breaks down under the heat that trailer bearings generate at highway speeds.
CRC Sta-Lube Marine Grease ($24.99) is specifically formulated for wheel bearing applications exposed to water. It resists wash-out, handles high temperatures, and provides excellent protection against corrosion — important for any trailer used near salt water or in wet conditions.
When re-packing bearings, work the grease in by hand until it's pushed through the roller cage from the back face. Don't just smear it on the outside.
Ready to Replace Your Bearings?
Autotrailer stocks Trojan bearing kits and CRC Sta-Lube Marine Grease with same-day dispatch NZ wide. Search by your kit part number or browse our trailer bearing range to find what you need.
