Help - Dual-axle vs. Tri-axle?

[Loren B.]

A am requesting information and assistance in making a decision about options on a new travel (bumper-pull) trailer.

The trailer we are considering will weigh about 12,000 pounds and be about 34-35 feet long. The manufacturer offers two options for axles. First is the standard axle with three axles. The other option is for two upgraded, heavy-duty axles. Either option would include hydraulic disc brakes.

I am leaning towards the tri-axle option for a few reasons. First, I like the idea of having more tires and brakes in case of a failure. With three axles, I have the option of just removing a wheel and driving to a service location (albeit at a slower speed) with just two wheels on one side. With two axles, that remaining single tire would be more seriously overloaded, if I were willing to try it at all.

Although there are 50% more tires, wheel bearings, and brakes to maintain, the tri-axle would have a softer suspension at each tire than a dual-axle trailer. I think this should result in a softer, more even ride. Each wheel would have its own suspension with either axle option.

I recognize that the tri-axle would produce more sideways tire scrubbing while turning, but this has not been a problem on my tri-axle Airstream.

I’ve had both dual and tri-axle trailers, and don’t have any strong feelings about one over the other.

Are there issues I have overlooked that I should consider before ordering my new trailer?

Thanks,
Loren

[LadyFitz...]

First, I do hope that by "bumper pull" you aren't planning on hooking that trailer up to a ball bolted to your bumper instead of a proper weight distributing hitch connected to a frame mounted receiver! Even if you didn't pull your bumper off as soon as you started out, the front end of your truck would have so little weight on it you wouldn't be able to steer worth beans.

The number of axles is less important than the actual total weight rating of the axles. Three axles would require 50% more maintenence than two axles (including eventual tire replacement). Three axles would be better for your trailer when towing since the load would be spread over a wider stretch of frame. The brakes are factored in when rating an axle's weight rating so you wouldn't really gain anything brakewise by adding an axle unless you overrate the axles. It's pretty much a toss up which is better.

It would be much safer and more economical to get a spare to use when you get a flat. When you take an axle out of the equation, you both redistribute your load which can cause your tongue weight to go too heavy or too light, either of which can make towing extremely unpleasant, if not downright dangerous (the one exception would be the center axle on a tree axle setup). Also, unless your axles are dramatically overrated, the remaining axle(s) and tires will be dangerously overloaded (this applies to both three axle and two axle setups, although the situation would be worse with the two axle setup).

[TXiceman]

If you are already towing a tri-axle Air Stream, you are familiar with the stability and straight towing of the tri-axle.

What are the axle ratings and tire ratings available with the trailer? I would go with which ever gave me the highest axle and tire rating.

I just replace the three 3500# torsion axles on my Avion with three 4000# axles so I could keep the 12" by 2" brakes plus a bit more weight reserve. The tires are already up rated and can carry the weight.


Ken

[taken]

Quote:

Originally Posted by LadyFitz... First, I do hope that by "bumper pull" you aren't planning on hooking that trailer up to a ball bolted to your bumper instead of a proper weight distributing hitch connected to a frame mounted receiver! Even if you didn't pull your bumper off as soon as you started out, the front end of your truck would have so little weight on it you wouldn't be able to steer worth beans.

Not sure if you know LadyFitz, but "bumper pull" is an old term meaning travel trailer as opposed to 5th wheel. The OP is not actually thinking of using a ball on his bumper. To the OP, I think the increase in stability of the tri axle setup outweighs the additional maintenance requirements. I say, go with the three.

[LadyFitz...]

Quote:

Originally Posted by taken Not sure if you know LadyFitz, but "bumper pull" is an old term meaning travel trailer as opposed to 5th wheel. The OP is not actually thinking of using a ball on his bumper...

I suspected as much but just wanted to make sure.

[Loren B.]

Many thanks to all who contributed here. I have pulled both dual-axle and tri-axle trailers and it seems that if the axles are properly positioned and the trailer is loaded correctly then it doesn’t matter as far as stability is concerned.
　
From what I can gather here, there are no strong reasons to prefer two axles or three axles.
　
I intend to get the tri-axle. The main reason is that I would expect a smoother trailer ride with three. Two axles would have to be rated for about 50% of the trailer’s weight, and would therefore be stiffer with stronger springs than three axles which would need only to be rated at about 33% of the trailer’s weight.

Last, no, I am not pulling this with a ball attached to my bumper. The factory hitch on my truck is rated for 12,000 pounds with a weight-distributing hitch and I intend to replace it with a Titan that can pull 18,000 pounds. No, the trailer won’t weigh that much, but it will probably be heavier than 12,000.
　
Thanks again for the input.
　
- Loren

[RVhauler]

Since you already pull a triple axle then you are familar with backing a triple versus a tandem axle. If tandem axles with dual wheels were available (such as on a 5er) then I would go that route due to the eaze in backing however I doubt if such assy is available. FYI I pull a triple axle Kountryaire 5er and a 38' flatbed tandem axle w/dual wheels. Can back flatbed in places easier than the RV. Have held a class "A" lic for over 50 years

[TXiceman]

I have never had any issues backing or turning my triple axle. Yes, the tires will scuff, but not badly.

Ken