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  1. #1
    New Member
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    Apr 2003
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    5
    Tractor
    kubota b7800

    Default Tire pressure

    Just bought new kubota 7800.
    Back tires have liquid, was wondering what pressure to run in tires, they seem alittle hard now the ride is rough, wondering if softening them up alittle would help. How low can u go without spinning the tire on the rim.

  2. #2
    Epic Contributor Bird's Avatar
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    Mar 2000
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    39,413
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    Texas

    Default Re: Tire pressure

    Which tires do you have? R1, R4, turf? One way is to drive it through a wet spot onto dry level concrete and see what kind of "footprint" you get. You'd like the tread to contact the ground all the way across. On my B2710 with R1 tires, that was about 10-12 psi.

  3. #3

    Join Date
    May 2002
    Posts
    302
    Location
    Houston, Texas
    Tractor
    TC33D / 7308 ldr 60" HD bucket

    Default Re: Tire pressure

    Hey Bird,

    This brings up a question I have....

    I put my guage on my rears the other day and water started dripping out of the guage. Is there a special guage for checking filled tires? will the water hurt the air gauge?

    I had the valve stem pointing up. I guess this is how you are suppose to check them? It made since to me anyway?

    thanks,

  4. #4
    Gold Member
    Join Date
    Dec 2001
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    364
    Location
    Woodford, VA
    Tractor
    NH TC33DA HST

    Default Re: Tire pressure

    I'm not Bird, but I am just about as old, and retiring this week, so there is some similarity [img]/forums/images/graemlins/grin.gif[/img].

    Your valve stem should be at the top of the wheel when you check the air pressure, so that the other end opens into the air pocket above the fluid. If you get fluid out of the valve stem in this position, you probably have too much liquid in your tires. I think the rule of thumb is 75% or just below the top of the rim for fluid, and air the rest of the way.

  5. #5
    Epic Contributor Bird's Avatar
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    Mar 2000
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    Texas

    Default Re: Tire pressure

    </font><font color="blue" class="small">( Is there a special guage for checking filled tires )</font>

    Yes, there are air/liquid gauges for filled tires. You can probably get one at most auto parts stores as well as tractor places. They don't look much different, nor cost much different, than a regular air gauge.

    </font><font color="blue" class="small">( will the water hurt the air gauge? )</font>

    If it was just water, probably not, at least if you got all the water out of it. If you have calcium, or if you leave water in it, it may rust.

    I agree with Casimir; I always tried to check the tire pressure with the valve stem at the top (12 o'clock), and in my case, I always had the air hose handy, so I'd give it just a quick shot of air before I put the gauge on just to blow any moisture out of the valve stem.

  6. #6
    Veteran Member chim's Avatar
    Join Date
    Apr 2002
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    2,249
    Location
    Lancaster County, PA
    Tractor
    Kubota L3200, Ford 1210

    Default Re: Tire pressure

    I have a 7500 with R4's and run 15 gallons of antifreeze mix in the rear tires. The R4's are fairly hard tires, and last Summer I dropped the pressure till I ran into trouble. That happened at 7PSI. At 10 or 12PSI, I haven't had any problems. If you ran R4's at the max pressure you may as well use wooden wheels.

    As you might already know, the liquid load shouldn't exceed 75% of the space...................chim

  7. #7
    New Member
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    Sep 2005
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    Default Re: Tire pressure

    Hi,

    I've run my WW fluid filled rear tires on the back of my Kubota B2910 at 12 psi for almost a year now without problems...backhoe and loader work mostly, but other things as well such as mowing with the RFM...

  8. #8
    Platinum Member
    Join Date
    Jul 2000
    Posts
    951
    Location
    Sierra Foothills, Northern California
    Tractor
    Kubota B7300; JD LX233

    Default Re: Tire pressure

    If the valve stem was pointing up you shouldn't get water out of it. Bird's suggestion to shoot a bit of air into it before checking is a good one - if you do that, the stem is "up", and get liquid then you have too much in the tire. Point the valve stem to about the 10 or 2 o'clock position and drain it until you get just air. Then pump it back up - 10 to 15 PSI seems to be a good number (at least for R4s). You don't want to have the tire filled much above the axle or else you are actually raising the center of gravity. 75% is about right.

  9. #9
    Super Member RickB's Avatar
    Join Date
    Sep 2000
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    8,638
    Location
    Eastern NY
    Tractor
    Case 885, Ford 4000

    Default Adjusting liquid fill level.

    For maximum ballast, use 11:00 or 1:00. Do this proceedure with the wheel jacked up, or you will displace too much liquid as the tire collapses on the bottom from the weight of the tractor. There is nothing wrong with tires loaded to "rim height" That has been commonly accepted practice in the Ag world since tires have been fluid-filled. Don't drain CaCL solution where it will do damage.

  10. #10
    Platinum Member
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    Jul 2000
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    951
    Location
    Sierra Foothills, Northern California
    Tractor
    Kubota B7300; JD LX233

    Default Re: Adjusting liquid fill level.

    <font color="blue"> For maximum ballast, use 11:00 or 1:00. </font>

    That'll certainly maximize the weight of the tire but I've heard some say that filling too much above the centerline of the wheel raises the tractor's center of gravity. I guess if you're going for max. weight (as in most agricultural applications like row farming) you'd want to do that. For me, on my hills, I want to make the tractor as stable as I can so I don't fill too far, keeping the COG as low as possible.

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