dock height, deck height, & trailer tires

Water heater loads from an weber come in trailers with jack legs that rais the tail to dock hight

 

We've done work at a few auto parts plants that have docks with ramps for "high cube" trailers...

The plant near my house used to have a fleet of high cube trailers going in and out, but the docks are hidden....

 

I was in Fontana at one of my furniture stops and had a guy park next to me with a drop deck van, he had air operated jack legs that raised the trailer to the dock height.

 

Yup, right between the tandems, they play with a valve and it raises 2 inchs at a time..

 

I pull auto parts in drop deck van...
The shipper/receiver needs a special dock for it. A normal 10' door is not tall enough, it needs to be a 12' door. It also need to either be built for drop-deck, or have portable ramps to lift the deck up to dock height. Then there is the nose of the van. Depending on the van, you might have to run the 5th wheel all the way back to clear mud flaps, which limits the weight. And you cannot slide tandems either (at least on ours), so again weight limited. Another problem with the nose, is unless you have a place setup for it, you will loose some of that space. The racks I pull are about 5 foot wide. That leaves an empty space on the nose between the racks and the bukhead of the trailer. Gotta always stop gently.
Also, at least according to our shop, the tires, breaks, and drums are horribly expensive compared to 'regular' 22.5" tires.
To be honest unless you have customers lined up that needs a drop desk I cannot see how it would be worthwhile.