They were rated at 1650 and it looks like 1800 no load wide open.  As for pressure, I'm not sure fluid makes a difference other than the volume of air needed.  I'd say the same pressure as a non filled tire.

AaronSEIA

     As a rule do pullers favor using  liquid ballast to increase traction?

Lou is dead-on about water column and hydrostatic pressure, but it has NO relevancy to air pressure in the tire... just how the weight of the ballast is borne upon the ground surface. 

The more important factor, is how well the tire 'molds' to the ground surface.

Remember when there were only steel wheels... rubber tires came out, and they exhibited more tractive effort for a given horsepower, than a steel wheel?  It's because the steel will naturally acted as a 'roller', creating a pile in front of it, which the wheel had to climb.  the rubber tire could deform slightly, causing it to naturally climb over what ever deforms in front of it, flattening it gradually, rather than trying to climb it all at once.

As for what your 'air pressure' charge should be, the greatest importance isn't ground pressure, it's bead slip.  If you don't have enough air pressure, the wheel will slip inside the tire.  I wouldn't run less than 10, and I'd probably remove the nuts from t he valve stems, just so I could see if the tube was suggesting migration.

What you WILL notice, in running ballast, is that the ride is rougher.  This is because when you compress the tire (over a bump) the volume of air you're compressing against is smaller (with more ballast).  The ballast fluid is NOT compressible, so the smaller the air volume, the more a given amount of compression will result in a higher tire internal pressure.

The best thing about tire ballast, is that it keeps the machine's center of gravity LOW... until you roll over, the weight is always on the BOTTOM side of the tire!

That being said, I run liquid ballast in my 'little' puller...  it's not an Allis... it's a Cub Cadet 109, with a stock engine i rebuilt.  Tires are about 2/3ds full of RV anti-freeze.  not a good comparison to a large tractor, though.

1 Foot of water = .433 PSI, regardless of the shape/width of the container.  Correct for actual density of antifreeze, CaCl, etc, and actual height!  You could probably tell a difference in pressure between 12 o'clock and 6 o'clock with a decent gauge.

    The math is 260 pounds of weights and 240 pounds of water.  I get what looks like the correct tire pressure for tire squat measuring at 12 o'clock at 4.5 psi. I may need to air up a tad for the 3500 class

    I now have the option of pulling in 3500 using another 500 pounds of suitcase weights at some point ahead of and behind the centerline of the rear axle. Finding the overall balance point of the added 500 pounds is the fun part I just have to guess at the start.

   Pulling in 3500 I also have the option of pulling in second gear.   Terry Dean's Data book says second gear a CA goes 3.5 MPH on 10 x 24 tires.  In my experience on 13-6 x 24 rubber I blow the horn in second gear where the limit is 3.5 MPH

I guess I misunderstood you

 

And whoever it was....of course standard practice is to measure at 12:00 to not "ruin" your gauge.  Just saying, you would notice a difference if you measured it.  And....they make sealed gauges.

     If I stall meaning I run out of ponys and can't slip the tires because I have more BITE than horsepower.  I have lots of fun experimenting with what I have and can get my hands on for weight classes where  there is more than just ME , MYSELF and I for competition.  In 3500 & 4000 classes with a stock engine I have picked up wins where I thought NO WAY against these Big Tractors

     Got to remember to keep your hitch point as close to the max allowable height all during the pull,  With a long drawbar I find it is real easy to  loose drawbar hook height comparable to how high the front lifts.   Ideally the front tires should be able to just float the track surface when the pull is about over but forward motion has not yet stopped.

    Our club sled that can start a Farmall Cub and stop a 10,000 JD 850 just by raising the hook point on the sled. This  shows how tractor hook height and sled hook height affect traction and wheel slip.

    I have been watching as many tractor pulling contests on the net as I can find. Never seen any Antique pulling less than 5000 class till yet

 This is how we pull a 2500 pound class.  First Video is the turboCA.

 

 

     I cut down and hauled off a big old bushy 6 trunk tree today that the top half refused to leaf out this spring. Talk about putting the 3000 pound CA to  the test dragging these big tops off into the woods to rot. She Pulled her little heart out for me in second and third gear.    Burned up more than 1 1/2 gallons of gas and never got the temp gauge into the green.  After this workout a pulling sled is no contest.  From the stump to where I dropped the tops in the woods was about a 1000 yards not 200 feet under load.

    I'm taking your advise and blew all the water out and dumped the weights.  If I remember correctly my lightest weight has been 2440 with 180 pounds of me on board. Plan is to weight the front with the 60 pounds and pull 2500 in second gear.  I'm about 15 pounds lighter this year. If the horn blows I just need to cut the revs 

     When I was dragging those big heavy tree tops I was impressed how gutsy the   CA is in 3rd gear at half throttle.

     I hope the pull on the 13th has a higher speed limit than 3 1/2 or better yet none.

 

     For 3000  I have to guess where to distribute 500 pounds of suitcases on the behind the  axle brackets and the belly brackets ahead of the axle.  All 500 behind the axle  even with a short drawbar  will make the front way to light.    I'm thinking 200 behind with 300 ahead on the belly brackets.   It's a 2 day pull so Friday I can experiment for Saturday.

     If I can pull 3500 I will have to borrow 500 pounds more of suitcase weights.

     Looking at the option of building a extended weight front bracket for the heavier classes