Keep those trailer tires turning with a good dose of the proper lubrication.
When you're hauling an average boat trailer with 28-inch tires down the highway at 60 mph, those wheels are spinning around about a dozen times per second. If they're not properly lubricated, there's a very good chance your boat trailer will one day be sitting on the side of the road instead of cruising along atop it. If that happens, we sure hope you have BoatUS TRAILER ASSIST® so you can get Mom's Mink towed to the nearest service station ASAP. Even if you do, however, canceling a day of boating due to a blown-out wheel bearing is no fun at all.
The best way you can make sure your trailer wheel bearings remain in good shape is preventive maintenance, and a big part of that is making sure they're properly lubed. But that doesn't mean grabbing any old grease gun and pumping any old grease into the bearings.
"Adding grease is not changing grease," says Dustin Hoover, of Legendary Trailer Repairs in Glen Burnie, Maryland. "Think of it the same way you think of engine oil. If your oil level is low and you add a quart, that doesn't count as an oil change. The same holds true for bearing grease. It needs to be changed on a regular basis, and just squeezing more in doesn't count."
Hoover recommends an annual maintenance and safety inspection along with cleaning and packing the wheel bearings, which includes checking the bearings for irregular wear or pitting on a regular basis.
Choose Your Weapon
Grease and grease guns are old tech, and Hoover mentions that there haven't been any Earth-shattering changes in their makeup, nor any modern developments that have shuffled this slippery deck in recent years. There are numerous greases specifically manufactured for use in trailer bearings. But the grease gun you choose can make a difference.
For the average trailer boater, the newer pneumatic and battery-powered grease guns are overkill. They're intended to allow you to pump grease rapidly and in large quantities. If you're not experienced in using them, they can lead to overfilling and seal damage. It's also unnecessary to buy a flexible hose grease gun, which is best for tough-to-reach fittings, because trailer wheel bearings are easily accessible and fixed tube guns can be operated one-handed once the barrel is seated on the fitting. So, even though it's dated, that ancient, inexpensive pump-gun with a 90-degree fixed tube is still the best tool for the job.
Also note that having bearing protectors is always a good move. The spring-loaded variety is generally considered best because they minimally pressurize the bearing to help keep water and dirt intrusion to a minimum. They also make it easier to visually inspect for grease level.
Just how important is it to make sure those bearings are ready to roll? Bearing failure is perpetually among the top-ranked reasons a trailer-related claim gets filed with GEICO, and in 2021, accounted for 11% of all mechanical trailer failure claims (excluding collisions). The word "critical" would certainly seem to apply.
The bottom line? Trailer bearings and the grease that we use to lube them haven't changed much, and the best practices of yesteryear remain the best practices today. We should note that greased bearings remain a completely different beast than the oil-filled variety that gained popularity a couple of decades ago. While these may be a good choice for boaters who trailer regularly and often, they aren't ideal for trailers that sit for long periods; the oil settles to the bottom half of the bearing and, over time, parts that aren't covered with oil can rust. On top of that, they're exposed to potential damage if you clip a curb, and the results can be catastrophic if condensation builds up over time. So for the average trailer boater, old-fashioned grease and grease guns remain the best ways to make sure those wheels keep turning.