I grabbed a quick measurement from our new 5er (2008 Heartland Big Country) and it was 59" from the bottom of the front portion of the body to the ground. That's measurement "D" in this picture.The trailer looked like it was sitting fairly level but I had no way to check that at the time so this measurement could be off. Now I measured from the ground to the top of the side of the bed on my 2015 Ram 3500 and I get 57 1/2", measurement "C". That's only 1-1/2" of clearance between the truck and 5er.The trailer didn't have a pin box on it when I saw it so I don't have measurement "A". It's now got a brand new Rota Flex pin box on it. I just got a Trailer Saver air hitch, but don't have it installed yet so I don't have measurement "B" yet either. How much clearance should I have between C and D to be sure I'm OK on inclines, bumpy roads, etc?

Subtract A from D. Now subtract 6" from the answer. Now place a straight edge (2x4) across top of bed side to side above at top of the hitch 5th wheel. Set top of hitch 5th wheel plate to the final dimension to bottom of straight edge and top of hitch 5th wheel plate. This will give you the 6" needed for bed clearance. B & C are irrelevant.

OK I see what you mean. But is there a minimum that D-C should be?

Well first of all unless you have the Ram air ride, your Ram 3500 will squat some. It seems to me that my 2016 squats a bit more than the old 2001 2500, the 2016 also rides better. You need to find out how much the hitch will move vertically as that will have an effect.That hitch may be a bit of overkill for a 14,000# GVWR , and will eat up a bunch of your zpayload.

BurbMan wrote:OK I see what you mean. But is there a minimum that D-C should be?I believe 6" is considered a minimum. Also consider C for the loaded truck rather than empty.This is the formula shown in your pic to need 6" but add 2" for rear squat of the truck.Roads in general are fine. It is the driveway entrances etc that may come close.

Do your measurements while hooked up with the landing gear retracted. Otherwise, the compression of the rear truck axle and the exact levelness of the trailer can easily throw your calculations off by a few inches.Now you just have to measure from trailer overhang to truck bed rails. (this assumes the trailer is sitting pretty much level and the truck is not squatting an excessive amount)

Bed Rail Clearance? | Good Sam Community

Cummins12V98
Explorer III
Feb 10, 2022
Subtract A from D. Now subtract 6" from the answer. Now place a straight edge (2x4) across top of bed side to side above at top of the hitch 5th wheel. Set top of hitch 5th wheel plate to the final dimension to bottom of straight edge and top of hitch 5th wheel plate. This will give you the 6" needed for bed clearance. B & C are irrelevant.
BurbMan
Explorer II
Feb 10, 2022
OK I see what you mean. But is there a minimum that D-C should be?
rhagfo
Explorer III
Feb 10, 2022
Well first of all unless you have the Ram air ride, your Ram 3500 will squat some. It seems to me that my 2016 squats a bit more than the old 2001 2500, the 2016 also rides better. You need to find out how much the hitch will move vertically as that will have an effect.
That hitch may be a bit of overkill for a 14,000# GVWR , and will eat up a bunch of your zpayload.
time2roll
Nomad
Feb 10, 2022
BurbMan wrote:
OK I see what you mean. But is there a minimum that D-C should be?
I believe 6" is considered a minimum. Also consider C for the loaded truck rather than empty.

This is the formula shown in your pic to need 6" but add 2" for rear squat of the truck.

Roads in general are fine. It is the driveway entrances etc that may come close.
valhalla360
Navigator
Feb 10, 2022
Do your measurements while hooked up with the landing gear retracted. Otherwise, the compression of the rear truck axle and the exact levelness of the trailer can easily throw your calculations off by a few inches.

Now you just have to measure from trailer overhang to truck bed rails. (this assumes the trailer is sitting pretty much level and the truck is not squatting an excessive amount)
Lantley
Nomad
Feb 10, 2022
I consider 6" of bedrail clearance the minimum amount required.
7"-8"is preferred. Generally traveling down the road is not the issue.
It's turning into or out of an incline that creates issues.
BurbMan
Explorer II
Feb 10, 2022
rhagfo wrote:
That hitch may be a bit of overkill for a 14,000# GVWR , and will eat up a bunch of your payload.

There are a few different models, I got the BD3 rated at 18,000 GVWR and 3500 pin weight. I thought it would be a good idea to have a little margin, they way things have been going who knows how long we'll have this trailer? LOL... Anyway, Hensley says it weighs 160 lbs which I though was in the range of most hitches.
Roger10378
Explorer II
Feb 10, 2022
You are going to have major problems trying to make this combination work. Back when the trailer was made the trucks were 6 inches shorter than the new ones are. I saw a post a few months ago from someone that canceled the order on a new F350 when he discovered how much higher the new ones are vs the older ones. I was thinking about a new truck but the only way I could make it work was either raise the trailer several inches or put a flat bed on the truck. I have opted to have my truck restored because I didn't like the other options.
BurbMan
Explorer II
Feb 10, 2022
Geez I hope not...I'm going to try and get up to the trailer and get some more measurements today. The problem is not unfixable by any means, if I have to put a lift kit on the trailer axles, that's what I'll do.

I added this Correct Track Alignment Kit to the TT get the 2" lift I needed to run 16" LT tires. Not the worst thing to go thru the suspension and put in new equalizers, bushings, shackles, etc.
ford_truck_guy
Nomad
Feb 10, 2022
BurbMan wrote:
Geez I hope not...I'm going to try and get up to the trailer and get some more measurements today. The problem is not unfixable by any means, if I have to put a lift kit on the trailer axles, that's what I'll do.

I added this Correct Track Alignment Kit to the TT get the 2" lift I needed to run 16" LT tires. Not the worst thing to go thru the suspension and put in new equalizers, bushings, shackles, etc.

You can always "FLIP" the trailer axles...If you do that, you will need to verify your HIGHEST point BEFORE you flip.... That will raise the trailer.. lots of info on flipping RV axles online...