one axle vs. two axles on short TT (20')

NanciL wrote:

atreis wrote:

My current trailer has two axles (and weighs 3300 fully loaded and is 21' - there are MANY shorter lightweight trailers with two axles).

I've had a flat on this trailer, and it went fine... My previous trailer had a single axle. I also had a flat on that trailer, and it also went fine. No sudden sway or other danger. So long as your setup is good - a good hitch, properly adjusted - it really doesn't matter much.

But I'll bet you didn't five five miles on that one wheel when the other one blew out !

Jack L

Assuming you meant something like: "I'll bet you didn't drive five miles..."

Correct. In neither case did I drive very far at all. I could have driven further with the tandem axle, at the potential risk that the damaged tire may have shredded and tore up the wheel well - not a good thing. Also, for most tandem axle trailers the one good tire would be severely overloaded. Just because you can do something doesn't mean you should.

mr61impala wrote:
Obviously wind resistance is the greatest constant load to your tow vehicle but is not rolling resistance the 2nd largest constant load? (Terrain being a variable).

Considering two otherwise identical trailer boxes would it not require more energy to tow the one with 4 tires as opposed to the one with 2?

FWIW our very first TT back in the late 80's was a 1965 Avion single axle that was around 20-21 feet long. Used W/D hitch, no issues at all.

You are correct. You also have more rotational force when stopping with tandem axles, but when I build trailers, I put brakes on all axles, which increases stopping power. You also have more "scuffing" with tandem axles, but that is a small price to pay for more load bearing area on the trailer. When the weights gets over 5,000# or so it really pays to have the second axle.

Most RV trailers currently being built don't have the aerodynamic qualities of a silver Avion.

Obviously wind resistance is the greatest constant load to your tow vehicle but is not rolling resistance the 2nd largest constant load? (Terrain being a variable).

Considering two otherwise identical trailer boxes would it not require more energy to tow the one with 4 tires as opposed to the one with 2?

FWIW our very first TT back in the late 80's was a 1965 Avion single axle that was around 20-21 feet long. Used W/D hitch, no issues at all.

atreis wrote:

NanciL wrote:

Last month coming home on I-95 going 65 MPh I had a blow out on one of the trailer wheels. All I heard was a pop, and the trailer never even swerved.
I don't think I would have been as lucky if I only had one axle!

My current trailer has two axles (and weighs 3300 fully loaded and is 21' - there are MANY shorter lightweight trailers with two axles).

I've had a flat on this trailer, and it went fine... My previous trailer had a single axle. I also had a flat on that trailer, and it also went fine. No sudden sway or other danger. So long as your setup is good - a good hitch, properly adjusted - it really doesn't matter much.

But I'll bet you didn't five five miles on that one wheel when the other one blew out !

Jack L

With a trailer of 3,500 empty, you are probably going to be in the 5,000# plus range loaded. My recommendation when you get over 5,000# is to go to a tandem leaf spring combination.
The last "camper" trailer I built used a 7,000# rubber torsion single axle configuration and it tows great. Because of the configuration I was limited to a single axle and I wanted the tires and wheels to match the truck. Otherwise, I would have built it with two 4,000# axles with leaf springs.
As far as tongue weight, I like to have over 10%, as long as the TV can handle it. Excess tongue weight (within the limits of the TV) won't hurt you, whereas too little tongue weight can kill you.

Safe Camping

69 Avion wrote:
The OP was asking about a trailer with a GVW of around 3,500# and a length of 22' or less.
As stated many times there are advantages and disadvantages of both. Having built trailers on and off for around 40 years I will express my experience with them.
First off, being a single axle or tandem axle has nothing to do with how well they back up. It is the distance from the hitch (coupler) to the center of the axle (or center of tandem axles) that determines how well they will back up. The shorter the distance, the harder they are to back up. Most folks don't realize that this distance also affect how well they tow. The shorter the distance the more any issues, like sway, will be magnified.
To the OP's question, in the 3,500# weight range it is hard to find decent axle arraingements with tandem axles. Most axle manufacturers start getting into their decent axles in the 3,000-3500# range. You aren't going to put two 3,500# axles on a trailer with a 3,500# GVW. Take a look at a 1500-2000# axle and you will see what I mean. The spindels, hubs, springs are not in the same league as the quality axles. I like tandem axles in most cases, especially with leaf spring instead of rubber torsion axles, because of the equalizer. Rubber torsion tandem axles can have all the weight on one axle when going over large bumps. That can create a huge problem.
Would I rather have a single axle trailer with a quality 3,500# axle or a tandem axle trailer with two 2,000# axles? I would take the single axle trailer every time. I recently built a single axle trailer with a 7,000# rubber torsion axle. It works great, but for that weight load I would prefer tandem leaf spring axles, but the length of the trailer didn't reasonably allow for that.
Most of the trailers that I built over the last 40 years were tandem axles, but there is a need, and use for single axles, just as there is for triple axles.

Interesting. Does axle placement vary much with TTs of a similar size? If the axle was father back wouldn't that translate to a greater portion of the weight in the front and a higher tongue weight? Assuming your truck can handle it is a higher tongue weight a problem?

I originally asked about a dry weight of 3500#, but I get what you are saying. That is an interesting idea about the weight rating of the axle(s). I looked at the specs of a couple of 1 and 2 axle 22' TTs. The dry weights were similar. The 2 axle ones had about 2000# CCC vs. 1000# for the 1 axle ones. I was wondering why it was only an extra 1000# for the 2 axles models. Your post cleared that up.

The OP was asking about a trailer with a GVW of around 3,500# and a length of 22' or less.
As stated many times there are advantages and disadvantages of both. Having built trailers on and off for around 40 years I will express my experience with them.
First off, being a single axle or tandem axle has nothing to do with how well they back up. It is the distance from the hitch (coupler) to the center of the axle (or center of tandem axles) that determines how well they will back up. The shorter the distance, the harder they are to back up. Most folks don't realize that this distance also affect how well they tow. The shorter the distance the more any issues, like sway, will be magnified.
To the OP's question, in the 3,500# weight range it is hard to find decent axle arraingements with tandem axles. Most axle manufacturers start getting into their decent axles in the 3,000-3500# range. You aren't going to put two 3,500# axles on a trailer with a 3,500# GVW. Take a look at a 1500-2000# axle and you will see what I mean. The spindels, hubs, springs are not in the same league as the quality axles. I like tandem axles in most cases, especially with leaf spring instead of rubber torsion axles, because of the equalizer. Rubber torsion tandem axles can have all the weight on one axle when going over large bumps. That can create a huge problem.
Would I rather have a single axle trailer with a quality 3,500# axle or a tandem axle trailer with two 2,000# axles? I would take the single axle trailer every time. I recently built a single axle trailer with a 7,000# rubber torsion axle. It works great, but for that weight load I would prefer tandem leaf spring axles, but the length of the trailer didn't reasonably allow for that.
Most of the trailers that I built over the last 40 years were tandem axles, but there is a need, and use for single axles, just as there is for triple axles.

No issues with my single axle, tows nice and has around 1000 lbs CCC. I haven't had a flat yet but have had a few on the old boat trailer and was never an issue.

NanciL wrote:

Last month coming home on I-95 going 65 MPh I had a blow out on one of the trailer wheels. All I heard was a pop, and the trailer never even swerved.
I don't think I would have been as lucky if I only had one axle!

My current trailer has two axles (and weighs 3300 fully loaded and is 21' - there are MANY shorter lightweight trailers with two axles).

I've had a flat on this trailer, and it went fine... My previous trailer had a single axle. I also had a flat on that trailer, and it also went fine. No sudden sway or other danger. So long as your setup is good - a good hitch, properly adjusted - it really doesn't matter much.

two axles = more tolls. had both and prefer one axle. both tow ok