Tire pressure

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Useful article on tire pressures

Bigger tires and lower pressures are the name of the game

How did he keep from blowing his tires up at the high pressures that I have never heard of any rear tractor tire even being rated to carry half the pressure he was using?

Operators manual for the 4020 lists max psi for a 15.5.38 tire at 24 psi which I have ran So your not going to blow a tire up

Another interesting combine effort to reduce cost .
https://www.youtube.com/watch?v=9eeOQNj0fqY

I like the Central inflation idea

What go me was the weight transfer 10000 lbs ,did I get that right ? Wow see now why the axles bust , cost of tires and axles cant afford not to use it with 10 percent fuel savings .

Go too low and you risk breaking down the sidewalls. I saw it happen with bias ply tires. Radials seem to be far more forgiving running lower pressure.

I'd just take a black Marks-a-Lot and block out the whole 6 psi line on his results. 12 psi is as absolutely low as I would go, with 14 to 18 as a working range. At 6 psi the sidewalls can buckle, tire bead slip on the rim. Yes, the tire squats a L-O-T and lengthens the footprint but does terrible abuse to Thousands of Dollars worth of tires. I'd follow the tractor Manufacturer's recommendations in your owner's manual that came with your tractor, and if you didn't get one get your dealer to order you one ASAP.
Dad used to run two 145# wheel weights on every tractor we owned, then he got a couple used tractors that had calcium Chloride fluid in them, 500-600# per tire. Was fine for plowing and disking, and maybe pulling a spring tooth cultivator but for pulling a 4-row cultivator with no fertilizer hoppers or spray tanks just putting duals on the tractor pulling the planter should eliminate the two wide green stripes of grass & weeds where the rear tractor tires ran. Bigger planter, maybe a 3-pt hitch mounted planter and spray tanks on the planter tractor, maybe use your FWA tractor with big wide frt tires, maybe even duals.
I can't stress enough that you should follow your tractor owner's manual for tire inflation PSI. I've got a couple rear tractor tires that would no more hold 35 psi than the could fly! We had duals on EVERYTHING, Except the lawn mower. Anything that drove on tilled crop fields had duals. The pickup with the bags of seed and fertilizer or herbicide/insecticide stayed on the traffic lanes and off the fields.
There was a couple farmers who never used duals, but they're all gone now, by natural causes. BTO I worked for bought a 2470 Case 4wd, WHAT a beast! Was turned up a bit over 200 hp, chisel plowed with it a couple days one fall, same chisel plow I pulled with a 4320 in about 3rd gear. And that Case rode like a Cadillac, had 4 nearly new Firestone 23 degree 28Lx26 tires. Every other 4wd tractor I ran was articulated, not a fan of them, When I turn the steering wheel the armrest on the seat beats me in the kidneys.

Radials are designed for low pressure bias plys are not .Ive ran 8 psi in mechanical front wheel drive tractors on big rubber . The lowest I can go with my biased plus is 10 psi which I run always unless i have s heavy mounted implement they I run 14 psi and duals