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We hooked up our old drill to our TJ430 and cannot get the power to the ground running between 10% and 20% slippage and running 70-80% power. Ground being wet is not helping us. We probably need more weight but not a option at this point. What is the optimal tire pressure for this machine, running 710-42 radials. Any other suggestions to get the power to the ground?
Cloud Sky Urban design City Building
 

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At an operating weight of 45000 lbs(20412kg) which is 104lbs/hp for 5mph loads, you should be ballasted to about 21500lbs (9752kg) on the rear axle and 23500 lbs (10659kg) on the front axle. Using a firestone load capacity chart you should be at 6 1/2psi on the rear tires and 7 1/2 psi on the front. You will need a low pressure guage to be accurate. I know it sound crazy but ran a case 9370 with 710R38 at those pressures and it pulled great. Learnt this at a tractor ballasting school many years ago where we played with ballast and tire pressures on a tractor equiped with a load cell to measure pulling capacity. Were able to turn a 250hp fwd into the pulling capacity of a 4020.

reason for edit: poor computer skills
 

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Looks like tomorrows job will be lowering the pressure in the tires and maybe try seeding again on Monday if the rain 🌧 decides to take a break. Thanks for the pointer, hopefully I can implement some of them and good luck everyone in getting this crop into the ground.
 

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As long as your sidewalls don’t touch I guess you can run low psi. Not sure I would want to road very fast at only 6.5psi in the tires. I know it’s dons wet dream to have tire inflation on all farm equipment.
 

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I havent had anything over 11psi since the bias tires left since that was the minimum for them.
I’ll see your lower inflation and raise you appropriate front and rear tire pressures to (including same pressure duals) maintain proper static loaded radius of tires…since the seventies.
Long, long before it was either fashionable or even thought of in general terms.

Still do it in my glorified grocery hauler (for 2) pickup.
 

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I have run 8 front and 14 rear for the last 20 years, STX 425. But I have never seen mud either...
Case IH ballast school, keep adding two psi to the rear until you stop power hop
You have considerable weight transfer under load, the front tires will stand up and the rears will squat. Need to be out of the tractor to see this happen, but it does,
 

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By pure (bad) luck I had a bit of a unscientific test back in about 1993.
Reed Turner of Alberta Farm Machinery Research Center (AFMARC), the original Lethbridge Prairie Agricultural Machinery Institute (PAMI) was going to come out and run test equipment on my CIH 9280 with 20.8R42 duals.
I asked which order he wanted to do of the low/typical/high tire pressures he wanted so we settled on low first and I set it the day before, about 20° out.
Next morning -10° and snow in the forecast so scrubbed the test.
WRONG!
A few flakes but nothing that would have affected us.
The 30° cool off had the tires looking pretty low so I took it for a spin pulling a cultivator seeder of the time.
Incredible traction, you could shift down a gear (12 speed PS) and load to to max engine torque yet have less slip than the day before in a gear up.
You would not be able to run tires of the day that low and expect any reliability but 20 years later…IF and VF tires show up and VF’s could be for sure.

But…until central inflation systems are married to automatic loaded radius sensing and pressure setting these tires can never be used to their maximum advantage and reliability.
You need automatic compensation of temperature and loads on these tires to fully utilize them, then they will rival tracks.
And that day is not very far away.
 

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Any over 500 hp needs tracks in order to transfer traction to the ground .
pulling up hill there’s a lot off stress on low pressure tires .
Central inflation is basically developed for tires on the road / on field situations.
Dont see many big 4wd loaded roading/ pulling
 
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