Wheel Bearings: The Small Part That Can End Your Trip

Wheel bearings are small, hidden, and easy to forget about. They sit inside the trailer's hubs and let the wheels spin smoothly. When they're greased and in good shape, you never think about them. When they fail, they can lock up a wheel, damage the axle, or even let a wheel come off. Here's how to stay ahead of them.

What wheel bearings do

Each trailer wheel spins on a hub, and inside each hub are bearings packed in grease. A seal on the back of the hub keeps the grease in and dirt and water out. A dust cap on the front keeps the outer bearing protected.

Bearings fail when:

• Grease runs low or breaks down from heat and age
• Water gets in, from rain, puddles, car washes, or boat launches
• They're too loose or too tight, after a poor adjustment
• The trailer sits for a long time, letting moisture settle in

Warning signs

Catch a bad bearing early, and it's usually an easy fix. Ignore it, and it can turn into a roadside breakdown. Watch for:

• A hot hub. This is the big one. After driving, one hub is noticeably hotter than the others.
• Grinding, rumbling, or squealing from a wheel
• Grease on the inside of the wheel or tire, which often means a leaking seal
• Wheel wobble. With the trailer jacked up, grab the tire at the top and bottom and rock it. Noticeable play can mean a loose or worn bearing.
• Smoke or a burning smell from a wheel. Stop right away.

The hub temperature check

This takes a few seconds and is one of the best habits you can build.

At every stop, especially after the first few miles of a trip, carefully hold your hand near each hub (don't grab it, it can be hot). All the hubs should feel about the same: warm is normal. If one is much hotter than the others, something's wrong. It could be a bearing problem, or a brake that's dragging.

Some people carry an inexpensive infrared thermometer to check temperatures more precisely. Comparing side to side is what matters most.

Add this to your pre-trip checklist and your fuel-stop routine.

How often to service bearings

Follow your axle manufacturer's guidance. A common recommendation is to inspect and repack bearings about once a year or every 12,000 miles, whichever comes first. Do it more often if:

• The trailer goes in the water, like a boat trailer
• It sits for long periods
• It hauls heavy loads often
• You notice any of the warning signs above

Some axles have grease fittings on the dust cap that let you add grease without taking the hub apart. These are handy, but they don't replace a full inspection. Too much grease can also push out the rear seal, so follow the instructions.

What a bearing service involves

If you're handy, you can do this yourself. If not, a trailer or auto shop can do it quickly. The basic steps are:

1. Jack up the trailer safely and support it on stands.
2. Remove the wheel, dust cap, and the nut holding the hub.
3. Pull the hub and remove the bearings and seal.
4. Clean everything and inspect the bearings and races for pitting, discoloration, or wear.
5. Replace anything that looks worn, and always install a new seal.
6. Repack the bearings with fresh grease, reassemble, and adjust properly.

While the hubs are off, it's a great time to inspect the brakes, too.

If a bearing fails on the road

• If you smell burning, see smoke, or hear grinding, pull over safely as soon as you can.
• Don't keep driving on a very hot hub. A failing bearing can seize or let the wheel come off.
• Let the hub cool before touching it.
• Call for help or have a spare hub assembly and tools ready if you travel long distances.

Tires and bearings go together

A hub that runs hot can also cook the tire next to it. And a tire with uneven wear can point to a bearing or axle problem. Check both at every stop. Our trailer tire guide covers what to look for.

Winter is hard on bearings

Michigan winters mean salty slush and freeze-thaw cycles, and trailers that sit until spring. Moisture is the enemy of bearings. Check out our upcoming tips on winter prep and storage, and plan a bearing check before your first spring trip.

Follow us on Facebook for a new towing tip every week.