End dump size

Best thing to do is looking at others in your area. See what they're running for equipment. Ask the local guys. In my area most work for asphalt is being done by Tri-Axles. Not tractor trailers. Most avoid aluminum, as sometimes they carry rip rap, or old chunks of concrete. You need to be able to chase all kinds of work. In Connecticut you register a Triaxle with an overweight permit for 80,000#. Same as a TT. Company I used to work for would lay 3/4 or 1" plywood on the bottom floor to protect it, and this was on a rugged steel body by Bibeau. The triaxles were 18' long, and we used 2 x 10's for the sides. And as tarp covers go, I don't think there is a better one than the Richards, made in Ct. Company has new name: http://www.thekingofcovers.com/contact.shtml
Good luck

 

You can't pave with a frameless or quarter frame, doesn't work with the drafting arms, if you are not paving, for any dump trailer over 28' I would go full frameless, personally hope I never have to go back to a frame trailer again

Also last I checked CT was 76500, but anything over 76 you were either over on drives or over on tags, but CT sucks so it's much easier to refuse to go there

 

It really depends on what you're actually planning to carry. As for asphalt, those are live bottom feeders rather than end dumps.
If your carrying sand or small rock go aluminum, your almost always restricted by weight rather than volume. If you're planning on carrying 3x5 or larger a steel trailer will hold up better.
Also research your state bridge laws, for example in Texas I can legally only gross 78k on the interstates due to my shorter overall bridge length. A sleeper cab or an extra 2ft of frame would let me carry 80k.

 

39 ft frameless 57 cubic yards mac or east that's what most use around here in pa,nj for stone/sand hauling.

 

Currently pull this. Florida spec 30ft tri-axle. 80k legal on interstate, 88k on regular roads. Require 43ft and 6 axles for those weights. 51ft and I could lose one axle. At 44.5ft with this one.

Hate the way the current one loads so I bought this a few weeks ago. 30ft frameless. Currently in shop to bring up to DOT requirements. I'll lose about 1500 lbs payload but for the cost to own this vs renting the above one I'll end up better in the long run right now.