Rear tire pressure

[Nosparkplug]

What air pressure do you use for actually working your tractor? I am trying to grade my yard( SC red clay) and my tires just want to spin. I do have weights and currently 20lbs of pressure. TIA
Charles

[Barnyard]

I usually run 12-15 psi.

[Nosparkplug]

If I went to 10 do you think I’d run the risk of spinning the rims?

[Eugene]

If I went to 10 do you think I’d run the risk of spinning the rims?

Spinning the tires on the rims? No.

12 to 15 psi is good.

More weight or chains.

[ricky racer]

More weight and less down pressure is the best course of action. Down pressure removes weight from the tractor increasing tire slippage.

[Matt Kirsch]

If I went to 10 do you think I’d run the risk of spinning the rims?

Not even close.

With a bias ply tire you want enough pressure in the tire to just take the "cheeks" out of them. At least that's the rule of thumb I learned on the farm.

[SamsFarm]

I could be wrong, but believe anything much more than 15psi for a Cub rear tire is overinflated!

[Glen]

Hi,
I use 12 psi in the rear tires. It works good with no load, or light loads on the rear of the Cub.
Below are pages from the 1965 Cub operator's manual with tire pressure tables for the different size tires that were available.
The tire sizes are the modern sizes.
The table shows 12 psi is ok to use.

http://farmallcub.com/rudi_cub/www.clea ... age-50.jpg

Here is the table for front tires, your tires probably need to be in good condition to use the higher pressures.

http://farmallcub.com/rudi_cub/www.clea ... age-49.jpg

[Nosparkplug]

I just checked and the new tire I mounted on a new rim had 20 because that was the max on the side of the tire. The new tire that I had a shop mount on an older rim was at 30. I’ll try that in the morning and see if it helps. Chains are an expense I can’t justify for a job that I can actually do with a mad-axe. I’m basically playing with my toy.
Thanks

[radioguy41]

Some of it is going to depend on what size tires on what size rims. For instance if you have 8.3x24's (7" wide) mounted on 5" rims then you might want a little less pressure, say about 10lbs, in order for the tread to flatten out a bit more. Mounting tires designed for 7" rims on 5" rims and pressurized at 15-20lbs will bow the tread so that only the middle is making ground contact.

Click on the photo to see it full size. Notice how only the inner half of the lugs are scuffed. That's because they are 7" tires on 5" rims. The bead and sidewalls are pulled in which bows the tread. Something to keep in mind. It doesn't matter to me since I don't do any dirt work with it but if I did I would find a pair of 7" rims and swap them. Another difference is going to be the ply rating. Lower ply rated (2-4 ply) tires will flatten out more than high rated (6-8 ply) tires will.

And finally, the angle of the lugs makes a difference depending on the field conditions, level/hillside - dry/wet - loose/firm, etc. Here's some interesting reading:

https://www.ntstiresupply.com/ptk-shared/23-deg-vs-45-deg-tread-angle