Dumb question about twisting tires/ Susp.

[Levinehikeski]

The flex on your sidewalls is coming from trying to pivot in the opposite direction from how a tire wants to rotate/perpendicular to the axle. Another way to explain it is the tread is trying to go one direction while the tire (and the rest of the trailer, due to your steering input) is trying to go in a direction the tire can’t turn so it twists. Not sure if I explained it in a way for everyone to understand. Try it with a toy truck and trailer, back it up and watch how it pivots on that (inside) tire.

And whomever thinks there is a differential in a non powered axle could benefit from some education on trailers/gears/vehicles. There will never be a differential in a trailer axle. Although it would be interesting to have an assist electric motor in a camper to help with steeper grades or looser traction areas!

[Adios Pantelones]

There are plenty of pickup bed trailers with differentials and assuming an unlocked and unpowered axle, they work the same as a trailer axle. I've attached a diagram of what happens as you increase the angle between a TT and a TV. the more the angle increases the more side force you put on the TT wheels. This force is also increased if your TV wheels are not turned. So in a sense folks are correct that they dont turn as well because they don't have a differential but that statement has the caveat that it has to be a powered differential that turns the wheels.
There are some things folks can do to change the angle of force and reduce scrub. If you are backing up at an increased angle remove your WDH bars if you have them. I also unhook my the TT power so I don't have brakes. Usually when folks are backing up they are apply the TV brakes which also applies the TT brakes and increases the scrub problem.

[JFlightRisk]

snip...

Originally Posted by Adios Pantelones

There are plenty of pickup bed trailers with differentials....

This is true, however, they're single axles, so there's no tire scrubbing or sidewall flex. At least I've never seen a double axle pickup trailer around these parts!

[gymracer]

Most trailers I use, enclosed 24' car haulers will twist the wheels, these are torsion axles, don't look good but nature of beast, been doing it for 20 years, no problem.

[schnydz]

A differential allows the inside tire and the outside tire to rotate at different speeds during a turn. A standard travel trailer doesn't have a differential. All the tires are independent of each other. Meaning they can all travel at different speeds with no regard to the other tires. There might be a tube connecting them, left and right, but they rotate independent of each other. When you make a turn in your vehicle the front tires turn left and right, obviously, so all 4 tires are traveling in 4 different circles. They are also all rotating at different speeds. On a tandem or triple axle trailer, during a turn, you have the same issue. They all want to travel in different circles and at different speeds. Which they can do, to a point. The tires don't turn left and right, like the front of your car, so during sharp turns some of them have to scrub/slide sideways. They can't all follow the circle that each one wants.

So back to the OP's issue. It is hard on the tires and the suspension of the trailer. They are designed, a bit, for this. It's not ideal but it happens to all trailers with more than 1 axle. This also goes along with what others have said about the trailer specific tires and always inspect your tires and suspension!

My 2 cents

[kregerca]

The big issue is when trying to move these in tight spaces both with parking and or turning it around. Has anyone ever used a tire dolly on one of the axles to allow the other axle to turn more easily?

[Cincinnati Kid]

The scrubbing also twists the heck out of the shackles. The bushings take a beating. There has to be a better way, maybe rear wheels on castors. (with very strong centering springs or rubber bushings)
OR- do like choo-choo trains, and put both axles on a single pivot in the center of the trailer. (again, this would have strong springs or bushings to keep the assembly tracking straight, since we seldom, if ever, ride on tracks.)

[craigav]

Rv'rs often debate the usage of LT tires instead of ST tires. One point that is often not made is that ST tires have less traction (which is why they can't be used on a vehicle), and they have stiffer sidewalls. What this allows for is less strain on the axles and components when turning sharp. Many years back I tried LT tires on an RV and when turning sharp I saw the entire wheel and axle lean and twist so much that I thought something was broken and shortly afterwards went back to ST tires. ST tires will do that as well, but much less than LT tires, at least in my experiences. ~CA

[Russc25]

Being a mechanic, you guys' talk of the relevance of differentials is straddling comical and painful. Whether or not there's a differential is irrelevant to the conversation, the issue is not differing turning circles left to right but differing turning circle centers front to rear. A diff is valuable when there's a torque link between the wheels... an axle that carries torque from the engine to both wheels. the diff lets the wheels turn at different rates due to the different radii around the same center. Campers have no such connection and whether there's a diff or not is irrelevant to the articulation the OP obseved.

The issue with tandem axles is you have four tires in a rectangle and you're trying to go around a corner. When you turn, only one (at most) axle can point at the center of the circle, the other (or both) have to scrub sideways some. The tighter the circle (tighter you turn), the more the scrub.

For those that don't see it yet, be amazed at my paint skills. the front of the vehicle is to the right so it's making a right hand turn. Lets say, hypothetically, that the front trailer axle is gripping more than the rear so the trailer's rotating around that one. There's a center to the circle and the wheels go round it (Red circles) since the rear axle is mechanically attached, it's also turning around the same center. The problem is that the tires are on that axle are not in line with the center of the circle (Blue circles) so they get dragged sideways, somewhat, proportional to the tightness of the turn.

I too noticed a lot of articulation on my new-to-me 5w as I basically jacknifed it into my driveway. My driveway and street doesn't have a lot of room to turn, unfortunately. Hmmm, the ditch needs to be dug out anyway, maybe it's time for a longer culvert too.