Let me educate you guys on mobile home tires and axles. I pulled mobile homes for over 25 yrs, pulled in 37 states pulling for federal government service members and construction company employees. Trust me, I know about them well.
Lots of utility trailers were built on them as they were free for the taking years ago and can still be bought very reasonable from mobile home dealers. Some guys will tell you they are outlawed by DOT if not on a M/H, but they are not. The axles are designed to carry a lot of weight, think about the weight of a M/H. In the 70's, the average house had only 2 axles. Today, the 50 ft homes still only carry 2. You aren't going to put anywhere close to that amount of weight on them unless you are hauling heavy equipment. For farm use or anything you are pulling with a pickup, they are more than heavy enough.
The old springs were "leaf" springs, meaning it had several "leafs" bolted together to make them heavy enough to carry the weight. The newer ones have a 1 piece spring, one solid heavy leaf instead of several leafs. I don't like the solid ones for utility trailer use, too solid, not enough weight to activate the spring. Use the older ones, more flexible and you can remove a leaf or two to weaken them for lighter use. I never weaken mine but the option is there.
Wheel bearings. They are solid and durable. The reason you see so many broken down mobile homes on the side of the road with axle failure is because they have been recycling them for years and nobody actually rebuilds them (usually), they spray paint them and send them back out to be used again. So, tear them down, check the bearings, repack with new grease and they have never given me one minutes problem in the 25 yrs I have used them on utility trailers. You can buy new bearings and seals at NAPA or any bearing dealer.
If you run the axle on the bottom of the springs, it raises your trailer higher off the ground. I have one trailer that I put the axle on top of the springs and bolted the springs back on with the same plates and U-bolts that was on it originally, did this in 1986, no problems, and I have had 7300 lbs on this single axle trailer and 6700 lbs another time. Another time I had 2 cubes of concrete blocks on it but I really felt I was overdoing it, but eased it along and no signs of damage when I got it unloaded. Didn't do that again.
Tires, now here is where the outlawed term comes into effect. If the tire has "for mobile home use only" on the side of the tire, DOT can fine you because it is NOT on a M/H. And some lil smart alec cop will do it. As the mobile homes got heavier, the factories building them started running "LT" tires, meaning "light truck" or "lowboy trailer". These tires are easily found and can be bought from a M/H dealer if you know him in the 25.00 to 30.00 range last time I bought any. As long as the tire DOESN'T have "for mobile home use only" on it, it is legal to run.
Mounting the wheel/tire on the hub. This is where people get into trouble by not knowing how to do it. When I change a mobile home tire, I only take off 3 of the 5 lugs/cleats. I never touch 2 of them, leaving 2 screwed into the hub that are side by side. The other 3 removed, bump the tire with a hammer or the butt of your hand and it usually pops right off. Put the new wheel/tire on and screw your lugs in paying attention to putting the cleat on in the right position. The cleat is usually marked, if not, pay attention to get the rounded side on the wheel, the straight side against the hub. And the wheel has a raised area that works to prevent the wheel from spinning on the cleats/lugs. Make sure the raised part is between your lugs and not under one. Snug your lugs down and tighten the center 1 of the 3 you took off, pulling the wheel back down to the hub. Tighten the other 2. Spin the tire to make sure there is no wobble, this is important, if it wobbles, it isn't pulled down evenly and the looser side will eventually work loose as you ride. Now after you have ALL lugs somewhat tightened, the wheel spins with no wobble, you need to "lock them down". You finish tightening the wheels by tightening 1 lug and skipping the next one in a "star" pattern. Tighten every other one pulling the wheel down equally as you do this. I might go around the series several times to make sure I don't get one side tighter than the other, but tighten them down good with a hand lug wrench or an impact wrench. And we all know what an impact wrench will do to car lugs, but a 1/2 inch impact wrench has never stripped out a mobile home lug with me UNLESS it was about worn out and bad threads to start with. You can feel it bottom out or lock down. Tighten it really tight as you are putting pressure on the inside of the wheel to hold it secure. And the "star" pattern of locking them down puts pressure evenly as you go around the lugs tightening every other one.
To visually check your lugs on a mobile home wheel, if you see the paint worn away in the lug area on the wheel between the lugs, the lugs/hub is spinning inside the wheel. It will eventually wear down the cleats and you lose your tire. Tighten them back up before you wear out the inside of the wheel and the cleats.
Fenders are important. Not only do they keep you from throwing mud or road grime in the rain, but they also keep your tires shaded from direct sunlight. Direct sunlight is murder on a rubber tire and if stored outside, you are also building "shelters" over your rubber.
If a person has no mechanical ability about them, I suggest they stay away from these kind of axles. But we are on a "build it yourself" forum and we all here have the ability to do these kind of things. With a lil education on the matter, these axles are heavy duty and work well IF you know what you are doing.
Another bit of knowledge about mobile home axles. Back in the 60's, mobile homes (10' wides) carried solid steel square axles, were usually a "drop" type axle, meaning the center of the axle dropped down to lower your frame closer to the ground. They had 6 lug "split" rims, the type of rim that had the removable band to mount-dismount the tire. The same axles also came on some of the 8' wide trailers/campers. If you happen to luck up on a set of these, GET THEM. They are really heavy duty. You can still get bearings/seals for them. And a 6 lug GMC pickup wheel will bolt right up on them. It makes great axles for a trailer and with later model pickup wheels, it works great. I've also seen some 6 lug straight axles from under older mobile homes that work great.
My understanding is a 6 lug wheel is just that, 6 lug, period. They are all the same lug pattern. But the hubs and brake drums are usually bigger than modern day hubs. So not all 6 lug wheels will fit over the drums, but the lug pattern is the same. So go with 15" wheels and they work well. And I have seen some 6 lug Mazda "offset" wheels that were 14" work too.
Hope this helps. I use mobile home axles on most of my trailers but I have the knowledge and access to cheap tires, so it was a win/win situation for me. And when I say cheap tires, I used Duroc lowboy tires I squirrelled back, was getting them on exchange of a regular mobile home tire that was blown. Self employed here so I wasn't stealing them, just taking the best home for my own use. When we had flats, the factories wouldn't buy our tires, but required us to bring in the flats and get a new tire for it.