Dual 14R20 on 5 ton

Master Logger,
I know exactly what you trying to achieve. Let me repeat for you.
Your truck empty weight about 15,000 lb
Your trailer is about 10,000 lb
And you timber goes up to 50,000 lb
So you have about 75,000 lb on muddy roads. So your toys are sinking.
Let see some numbers:
truck weight + 1/2 trailer weight + 1/2 load = 45,000 lb sitting on 6 wheels 14R20.
The ground pressure is 25.79 PSI.
Just compering to 6 wheeler civilian truck loaded 33,000 lb. It has 33.53 PSI.
So it is not bad.
however if you comparing to 200 lb person standing on one foot - about 10 PSI.

If you will put dual 14R20 on back you truck will create 15.47 PSI. Wow it is grate.
Just to play around I plugged into my calculator:

Configuration now:
Front - 14R20
Rear 2 axles - single 14R20
Pressure = 25.79 PSI

dual 14s configuration:
Front - 14R20
Rear 2 axles - dual 14R20
Ground pressure = 15.47 PSI

What if you put single 16R20 instead 14R20 -
front - single 16R20
rear 2 axles - singles 16R20
Truck's pressure - 19.24
apparently it better when single 14s but not as good as dual 14s.

I got some other configuration for you:
front - 16R20
rear 2 axles - 24R21
pressure = 15.19 PSI
whey (16s and 24s) very close by diameter.

Lets see if you can add one more axle on back:

Front - 14R20
Rear 3 axles - single 14R20
Pressure = 19.34 PSI


Front - 14R20
Rear 3 axles - dual 14R20
Pressure = 11.05 PSI


Front - 16R20
Rear 3 axles - single 16R20
Pressure = 14.43 PSI

this is some interesting ideas ...

adamsoffroadperformance said:

The bridge trucks that ran them had a wider rear axle housing and an 1.5" spacer on each hub, the front axle had 3" wheel spacer on each hub to accomplish the use of the 10" wide Budd wheels. I have the front spacers and studs if someone needs a set.

Click to expand...

Do you still have the front spacers and studs?

you can run an M939 wheel on the inside at rear and a bridge truck wheel outer



5T-915 | Hub and Brake Assembly, Bridge Truck Right Hand (RH)
Hub and Brake Assembly, Bridge Truck Right Hand (RH) for M821 M812A1 5-Ton Trucks M139 series Bridge Trucks
NSN #: 2530-01-220-7762
Part #: A16-333-U-801
$595.00


5T-916 | Hub and Brake Drum Assembly, Bridge Truck Left Hand (LH) M139 M812
Bridge Truck Left Hand (LH) Hub and Brake Assembly for M821 M812A1 M139 5-Ton Trucks
NSN #: 2530-01-101-8357
Part #: 8758334
$475.00


5T-793 | Left Front Extra Long Wheel Stud Bridge Truck M139 M812 M945
Left Front Extra Long Wheel Stud Bridge Truck M139 M812 M945
NSN #: 5306-00-569-9018
Part #: MS51947-1
$29.00



5T-794 | Right Front Extra Long Wheel Stud Bridge Truck M139 M812 M945
Bolt, Ribbed Shoulder/ Front Right Wheel Stud. BRIDGE TRUCK. M812 and M945
NSN #: 5306-01-206-8407, 5306-01-289-9776
Part #: MS51947-2
$29.00


5T-917 | Spacer 1.5 inch Hub and Brake Assembly 5 Ton, Bridge Truck Rockwell Axle 5 Ton Truck
Hub and Brake Assembly 5 Ton Spacer, Bridge Truck for M54 M809 M939 5-Ton Trucks
NSN #: 5365-01-132-2015
Part #: 3280-A1977
$49.00




9M-774 | Wheel Rim for Bridge Truck Extra Wide for Bridge Section Carrier Trucks 10 hole
Bridge Truck Rim, wheel
NSN #: 2530-01-289-3962
Part #: 12356821
$419.00