At 60 MPH a 8 inch wheel is going about 2500 RPM and a 13 inch wheel is going about 1680 RPM. However the bearing size it self may make those numbers closer (not in the actual speed but what RPM they are good for) as a smaller bearing can normally rotate faster than a larger one. Ball bearings can go faster than tapered roller bearings, oil lube faster than grease and oil mist even faster than oil. All of that has to do with heat. I will have misspent 43 years in the bearing business this fall and pretty much seen every bearing failure known but lubrication issues both too much and too little and heat top my list.
... differences, since the larger the bearing, the faster the rollers must travel (spin) for a given wheel RPM. Fortunately, this discussion seems mostly to be centered on whether to put 8-inch or 12-inch wheels on the same hub, meaning the same bearings would be used in either case.
In regard to your other comments, I have often wondered about the reasons many modern truck wheel bearings are bathed in oil instead of being packed with grease. Sounds like you'd be a person who'd know. I won't insist on delving into that right here, but feel free if there's such a thing as a concise answer.
Actually With taper roller bearings the same bearing, say with a 1 inch bore, could use up to a dozen different races of different OD’s. When I say bearing size I am referring to the ID and OD added together and divided by 2 to get the center line which we use to get what we bearing people call the DN value which tells us the limiting speed based on lube type. Anyway the 8 inch wheel could have a smaller bearing on not. The biggest problem in trailer bearing’s is where they are made and today most of them come from a very large Asian country that cost much less than domestic bearings.
I've never pretended to understand the terminology of bearing sizes (thank goodness they are stamped with a number that allows me to "ask someone who knows" when replacement is needed).
Still, when the people here talk about interchanging 8-inch and 12-inch wheels on the same hub, the bearing that's used will always be the same, which was all I was saying in my previous post (they aren't switching hubs or the bearings within the hub - they are only switching wheels).
Oh, and are you saying the quality of bearings made in China isn't always as good as it could be? Who'da thunk it? (hee-hee)
Bigger wheels=better chance to avoid any sort of road debris from fresh accidents.
I try to avoid the freeways here but must use them for some routes to put- ins, and I have been really grateful for the higher clearance of 4 wh drive every time I’ve been forced to run over and straddle something that wasn’t picked up yet because there was no way I could change lanes in time. And driving here, even if you do slow down, means that crazy people are ALWAYS weaving in and out as if they’re in a video game, trying to get by and you have to be super vigilant to avoid their stupidity.
I’ve seen lots of boat trailers along side the road, too, with a wheel missing… they are usually parked southbound, which means that they broke down on the way back from the lake(s), and they didn’t make it with the Barbie Wheels. Not how I’d want to spend my Sunday evening…
I have 8" on my 1969 Montgomery Ward Western Field tent trailer. I can’t remember how many miles I’ve put on it, but it has traveled a lot over the years. American bearings and good care probably have much to do with success. Also, I use the high temperature disk brake grease, not normal ball joint grease. It semi retired for a while, then made a few more trips, and is waiting conversion to a boat hauler. Quality parts and good care make all of the difference.
Size Size is still the ID and OD and with. We only use the DN value when looking for the max speed. Not something we do every day either, most of the time it is when some Gyro Gearloose is going to reinvent something.
Lots of factors As Old Bill is well aware, one of the engineering aspects that is considered in bearing application is a theoretical maximum number of revolutions a bearing can be expected to do in its lifetime. Smaller wheel and tire equals lots more revolutions per mile than a bigger wheel, so everything else being fairly equal, the bearings in the larger diameter wheel should last much longer.
All of this is just jibber jabber anyway. The point is that up to a point, the bigger wheels should equal more reliability and a safer ride for your boat. The idea of an itty bitty trailer with itty bitty wheels ripping along down a freeway with expensive boats on it doesn’t work for me.
Really? It would be great if manufacturers were always concerned about the quality and durability of their products, but that notion is simply a fantasy. All too often it is the market, production costs and many other factors that takes precedence over quality. That’s just the way things are.
wheels are. And that not all bearings are identical. I also don't see anything on the web regarding the fragility or danger of 8" trailer wheels when carrying extremely light loads, like, say, a pair of kayaks.
Also, there are other manufacturers who try to sell you crap you don't need.
I live near a few north-south highways that are absolutely packed with vacationers from Illinois on every summer weekend. You wouldn't believe the number of motorboats on trailers that you see on these highways. For much of my life (and for decades before my memory of such things began), the vast majority of those motorboats were small ones, all hauled on trailers with 8-inch wheels. Though on occasion you see a disabled trailer on the side of the road, that number is miniscule in proportion to the number of similar trailers that are actually passing by. Nowadays, most boats towed by these vacationers are several times as heavy as what used to be the norm, and the trailers for those boats typically have 12-inch wheels. Others have stated that nearly all bearing failures are the result of crappy maintenance, and that makes perfect sense in terms of what I actually see on the roads.
Considering the fact that 12-inch wheels became the norm after the weight of the average fishing rig approached or exceeded 2000 pounds, and that 8-inch wheels worked fine for decades for countless people with fishing boats weighing 1,000 pounds or less, I sure don't see the sense in recommending a trailer with 15-inch wheels for carrying a load that's so light that the average person can carry it in his hands. Every trailer I see with 15-inch wheels is far better suited to hauling small tractors than kayaks.
By the way, come wintertime, the Illinois vacation traffic continues, this time with snowmobile trailers. Only in recent years have we started to see snowmobile trailers with 12-inch wheels, and those are covered units that carry six machines. The typical 2-machine snowmobile trailers still have 8-inch wheels.
Oh, one more thing, is that not many Illinois drivers go the speed limit. Most of them really fly. I think the sheer abundance of those folks and the speeds that they travel provide good evidence that 8-inch trailer wheels are up to the task.
Finally, I have no disagreement with the idea of putting on 12-inch wheels instead of 8s, but to go the heavy-duty route just because "it must be better" is going way too far.
Snowmobile trailer changes The Triton one-snowmobile trailer we used to use for hauling sea kayaks had a plywood-floored aluminum frame that sat OVER 8" wheels using Torflex suspension. This was perfectly adequate for all our needs, from Interstate highway to rutted dirt roads and everything in between. The trailer didn’t have or need fenders and it had good ground clearance despite the small wheels.
Later versions of this trailer from the same manufacturer came with 12" wheels and the snowmobile platform slung BETWEEN the wheels, as you usually see with boat trailers. I would guess that the earlier version with its narrow wheel track and a heavy snowmobile on it was more tippy (never an issue with our sea kayaks). Changing to the newer design would improve the weight distribution while preserving the fairly high ground clearance of the older design. But it must be heavier, albeit not relevant if you never hand-pull the trailer uphill like I used to do. The old trailer sat well within the tow rig’s width, making for less wind resistance–pretty nice. The new design would force the wheel track to be noticeably wider.
Our old trailer was only 4.5 ft wide total. The Trailex kayak trailer’s wheels and crossbars span 6 ft., which is probably similar to the newer snowmobile trailer’s total width.
Speed limits, LOL. While I have driven the trailers faster to pass or other short bursts, I keep sustained driving speeds down to 70 mph or less even when the posted limit is 75 mph as if often the case on rural western Interstate highways. And my husband and I do the same on the rare occasions of rooftopping. Just because you can “get away” with something that pushes the limits of something’s ability doesn’t mean it’s a good idea over the long term. Yeah, I used to shoulder-carry my sea kayaks that weigh more than half what I do…for a short distance.
I’m getting to the conclusion that overbuilt is better (the snowmobile trailer was overbuilt for hauling kayaks), but that doesn’t have to mean oversized or overweight.
Right There is a bearing grease rated for the higher temperatures that disc brakes create, another bearing grease for lower temps of regular bearings and ball joints and such. I haven’t had to replenish my stock for awhile and maybe they are making a multi-temp grease these days.
Tire age is a big factor there. People don’t realize that even though the tread may look OK the ozone has been deteriorating the rubber. Look for the date code on the tire and for sidewall checks.