Tri Axle Flat/Dropdeck

I'm planning to do the same. The extra axle doesn't add much to the empty weight but does allow you to carry more weight. I see it as a positive all the way around

 

I've been pulling a triple axle 53' cattle pot for the last year followed by 2 years pulling spread axle flats and steps and I would highly recommend going to the triple. We run a single,dual,single configuration so its the same # of tires on the ground, but you can put 42k on that instead of 40k on a spread. Tight turning is sooooo much better. You can jack knife it into tight spots all you want without watching the frame twist and tire wear is much better.

The guy that owns my trailer tells me that the triple axle actually weighs 150 lbs less than a spread if you run a single,dual,single config. like we do. Really no downside to it from an operational standpoint at all and he said that they are actually less expensive as most people don't want them. I don't know about the last 2 statements as they are just what he told me, but pulling them I can tell you I'd never go back to a spread if i had a choice.

I don't know why people still run spreads outside of satisfying kingpin requirements in places like CA.

 

Permitting more weight on a non divisible load is also a benefit. Some states will give you 60k on a tridem if spaced corectly

 

I'll have to look and see if I still have my notes in my book when I get home. But I know when it comes to the tri axle steps I've pulled there's more to it than just an extra axle, the ones we had were all around heavier built. The main beams were heavier the top deck was longer and that made the lower deck longer (I'm sure it could be speced different) you also loose you sliding winches between the axles. For normal highway freight I can't see an advantage.

 

True about the sliding winch loss: but you can get tricky like @MJ1657 does with his step. Short piece of chain and voila

 

Any way you slice it: an extra axle = more weight; the number of tires not withstanding. Single/dual/single configurations are quite on tridem platforms are not real common.

The upside is more brakes, and more "registerable" weight in many states. (I am good for 99k, no permit needed in New England and several contiguous states) Additionally, you can permit for more weight if needed.

Downside? They are heavier!! A tridem step will be a grand heavier; even on 17.5 rubber. That said; you need a compelling reason to want one, it's not just a cool trailer to throw general freight on. I have a 50' tridem, Doonan combo......purchased for a specific haul. Do I haul "other" stuff on it?? Heck yes; but never would have got it otherwise.