Math formula for load placement

Very close. It not a single line formula, it's an equation (think fraction). This one is, because he supplied part of the overall equation. If in these cases where the axle tare weight are known, this is the simple formula
(a / P) w = T (Key for input numbers below)
(45000 / 70000) 41 = 26.38
45000/70000=0.643 or 64.3% of the load to the rear.
41*0.643=26.38 or 26'4" from the kingpin hits the target weights of your axles

Formula Key
a = actual payload weight required to hit target axle group
P = payload weight
w = wheelbase of the trailer (kingpin to center of axle group)
T = Target measurement from kingpin to COG of payload

 

Yes this can also be calculated, it's just done inverse. I do this one quite often, as I move loads that sometimes have to sit "in the well" due to height, COG just lands where it lands and one end is heavier than the other like it or not. Just make sure you have enough axles to cover the heavy end. I recently moved a high load that was only 72000#, but due to the only way to place the load it landed 39+, 39+, 32-, 32-. I didn't need 9axles for the weight of the load, I needed the configuration due to placement & concentration of the load.
My bad, I got tardy and forgot to write this up with the formulas. I have some other paperwork to do as well this weekend, I'll try to get it together and post it somewhere in the midst of that stuff.

 

awsome pic old iron!

 

You're light on the drives. Even with 36k axles you'll still be able to permit 40k in most states on a tandem so at 70k payload you'll have 11000 lbs to play with. The math is right tho.

 

Yes the permit office will, because they can't visually inspect your unit. If the scale decides to come out and check your door post for manufacturer ratings, and you've exceeded them...not so much!
I've only ever had that checked twice in my 25+yrs...

 

I haven't been doing this as long as hammer has but I've never had them check my door. That being said there's always that possibility but I wouldn't worry too hard.

 

I'm the same, 18 years never been checked. I did catch heck for tire ratings on an old trailer we had that had 19.5's on it. But it is a very real possibility.