Question: I’ve heard that 8 inch wheels on a trailer are a problem but I’m not sure. I’ve heard the bearings run hot. What is your opinion on 12″ versus 8″ wheels?
Answer: The short answer–8″ wheels are fine. On some trailers they are the only choice due to the design. I would not make a buying decision based solely on wheel size.
The longer answer is that the problems people have with bearings has more to do with maintenance than wheel size. It is true that an 8″ wheel turns faster at the same highway speed than a 12″ wheel, that’s just mathematics (or geometry or algebra or physics or something, I dunno.) However, today’s axle assemblies use bearings that are designed for much heavier loads than a motorcycle trailer or camper will EVER carry, so when you’re tooling along at 80 mph on I-90 out west, properly maintained bearings can handle that all day long, day after day.
To achieve the proper ride height based on design, sometimes an 8″ wheel is the only choice. For example, the Mini Mate and Time Out campers both use 8″ wheels and as a class motorcycle campers are heavier than cargo trailers. I’ve towed both thousands of trouble-free miles.
The key is keeping the bearings packed with fresh grease and this is not a big deal either. If you are a casual tower and don’t ride in a lot of rain, you may need to service the bearings just once every few years. This consists of pulling the dust cap and castle nut off the hub, pulling out and wiping off all grease from the bearings and hub, then repacking with fresh high speed high temperature grease.
12″ wheels do have a couple of advantages but, as I said, they are not deal makers or breakers for me. A 12″ wheel will not step as deeply into a rutted road surface, so it pulls fractionally smoother over rough surfaces. And there are a few more design/material options in 12″ wheels, chrome and alloy, so you have some different looks. But that’s about it.
Bottom line, I’d not hesitate to pull a trailer with 8″ wheels and I wouldn’t worry about maintaining a specific road speed to “save” the bearings.
Have a question about motorcycle trailering? Feel free to e-mail me, firstname.lastname@example.org and I’ll try to answer your question, or point you in the right direction.