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

westend wrote:
If considering alike travel trailers, one having single axle and the other, a tandem set, I would choose the trailer that is built better. There is a lot unknown how a trailer will tow, regardless of axle count. Tandem axles will support more weight and for some, that is a great attribute. I have a 22' with tandem axles supporting 5K lbs. It tows like a train and stops adequately.

Even though I respect Avion69 quite a bit for his trailer building skills (and he's helped me a ton), I'd differ a bit on the ride quality of sprung axles over torsion bar for a small TT application. My current TT has two torsion axles with shocks (I've forgotten the ratings). It is the smoothest towing trailer I've owned (current count is 6). Part of that may be due to the low attitude but the torsion axles are a highway dream.

The issue isn't as much the ride as it is the stress when one rubber torsion axle has to carry most of the weight of the entire trailer when you hit a bump that is greater (or close to) the travel of the axle. When you hit a 6" speed bump and the axle only travels 5", one axle will carry the entire weight of the trailer for that bump. A leaf spring has an equalizer so you get the travel of the equalizer plus the travel of the leaf springs. If you aren't hitting large bumps, a rubber torsion tandem trailer should tow real nice and ride nice as well.
If I were picking the "ride" of an individual axle, I would pick the rubber torsion over the leaf spring. The other issue is lateral stress when cornering. It isn't real bad with tandem axles, but it can be tremendous with triple axles. Some rubber torsion axle manufacturers don't recommend their RT axles for triple axle configurations because that stress can pull the rubber swing arm right out of the axle tube.
They all have their positives and negatives. Most of the time a person doesn't get their choice when buying a trailer. Another down side of the rubber torsion axle is that the rubber is usually only good for about 25 years. Then it is time to buy a new axle because you can't replace the rubber. In many cases the TT needs a rebuild by that time anyway. A positive attribute to the rubber torsion axle is that it can be used as part of the structural integrity of the trailer frame and it is easier to install. A real nice positive attribute to the rubber torsion axle when using the Flexiride axle is that the torsion arm angle can be adjusted in about 30 minutes. That can come in real handy.