Rear most storage boxes dimensions??

[rpsinc]

Working on some modifications on my bed and need info about the clearance needed for a box I will place behind my tandem rear tires.  Some of you that have designed and built your beds, what is minimum distance from the ground to the bottom of a box for clearance to prevent hitting the box.  I plan on using a box I already own and making accomodation for my Smart ramps which will facilitate moving my hitch back about 20" for clearance to the Smart with our new to us NH.  

Any input from the voices of experience is appreciated.

[Steve from SoCal]

My truck is singled but, the issue is the same, approach angle.   How far behind the axle centerline is box?     My rear boxes extend 46" from the centerline of the axle and at ride height are 15" from the ground.     I have a rather steep driveway entry and, use a drive on grain scale with quick riseing ramps.    With my suspension dumped there is 12" clearance and plenty of room on these.    The longer the overhang the more height you will need.    I don't recall what angle I used but 12-14 degrees seems in the ball park.

[phoenix2013]

Integrated the rear fender skirt into the box front, cut out the door from the skin.

Two front and two rear skins attached to real boxes

The rear boxes were quite big.

[rpsinc]

Very helpful guys.  Thanks.  This will provide a good start to my design.  Its raining here in So Cal so have some time to do inside work.

[rpsinc]

Will be repurposing 1 of the 2 of these that I already have.  My doors open the other way and I will have those opening to the rear.  78" long will allow for 10" boxes on each side to house the lights.  The top tray will be modified for ramp storage, either in front of the box(which will be toward the cab) or on top of the box, which is built for chain storage on rollback tow trucks.

Henry-what did you use to extend the frame for the hitch support.  I am thinking some 3/8" roll formed Cs made long enough to bolt to existing frame or weld to end and splice plate.

 

 

[Darryl&Rita]

We're about 6" or 8" off the ground, 50" behind the tires. We drag, we knew we would drag, we built for it. Hammer down, power through. I can get exact measurements in a month, if I remember.

[rickeieio]

We're a bit more conservative than Henry's drawing, but not much.  Bumper is 12" off the ground and roughly 40" from rear of tire to extreme rear of bumper.

[phoenix2013]

2 hours ago, rpsinc said:

Henry-what did you use to extend the frame for the hitch support.  I am thinking some 3/8" roll formed Cs made long enough to bolt to existing frame or weld to end and splice plate.

 

 

 

1/4 inch plate rolled with the same radius as the frame, attached at the end of the slope. V grove both sides, weld both sides, grind inside flush to slide the hitch mounting angles in. Frame is about 1/4 inch thick so it works. Used to order it in two two footers or one four footer and cut these to length depending on the bed design.

Finished and painted

 

[rpsinc]

4 hours ago, Darryl&Rita said:

We're about 6" or 8" off the ground, 50" behind the tires. We drag, we knew we would drag, we built for it. Hammer down, power through. I can get exact measurements in a month, if I remember.

No need but thanks.  I will do what works for my situation but now I have a much better idea of what my min/max is.

[Darryl&Rita]

It should be noted that when I say that we drag, it's not every day, or even every trip. It does happen, but only barely occasionally. Mostly when one of us hasn't been paying attention. Probably once per year.