Tire Pressure with Liquid Ballast

[Gryz]

First tractor owner. Got my Yanmar out for the Spring and wanted to check the tire pressure. Manual says for my R4s, front 35psi, rear 30psi. Fronts were about 32psi, so I left it. I know there is liquid ballast in my rears so I put the valve at the top and checked with my analog pressure gauge. Gauge shows 8psi. Thought that was strange so I checked the other rear...8psi. Is that because there is less air volume available? What should the rear psi be if there is ballast?

 

[WinterDeere]

The liquid is (at these pressures) non-compressible. So, the compressible volume is reduced to about 10% of what it would be without liquid ballast in the tire, and thus you become much more sensitive to the small amount of air that migrates out of the tire over the course of the year. Just like your low-profile sports car tires always show low before your 70-profile pickup truck tires.

That said, some do prefer to run lower pressures when filling a tire with liquid ballast, as the tire will run much stiffer at the same pressure. Same problem as above, you've reduced the compressible space, so every bump which would have been previously absorbed by compression is now felt like you're running solid rubber tires. I can't say if 8 psi is a reasonable target, seems a bit low, but as long as you're not worried about popping a tubeless tire off the rim, running the rears a bit lower isn't a huge harm.

Fronts should always be run according to the manual, or near max spec if the manual doesn't state otherwise, when running a loader.

 

[WinterDeere]

Oh, and if you're checking them on a typical 60 or 100 psi gauge, don't believe that 8 psi is accurate. Gauges are most accurate near 50% full scale, and most are only spec'd for a given accuracy (eg. 2%) at 30% to 70% of full scale. So, if you're measuring 8 psi, you'd do well to use a 15 psi gauge, which is the closest common increment placing that pressure near 50% scale.

 

[ericm979]

They make special tire gauges for filled tires. The one I have is a pencil gauge and what makes it special is that it's spring loaded so it returns to 0 when you take it off the valve stem. But I found that with Rimguard the gauge still loads up with fluid and gets sticky. I bring a pan of warm water out with me when checking the rear tires, and use it to rinse out the gauge between readings. Don't leave the gauge with Rimguard in it or it may be ruined. The same may be true for some other common liquids used in tractor tires.

I'm running ~15 psi in the rears on my Branson. Basically I let air out until the tread on the edges of the tire touch the pavement. It rides better than the 20 or so it came with from the dealer.

 

[MF243RedTop]

They make special tire gauges for filled tires. The one I have is a pencil gauge and what makes it special is that it's spring loaded so it returns to 0 when you take it off the valve stem. But I found that with Rimguard the gauge still loads up with fluid and gets sticky. I bring a pan of warm water out with me when checking the rear tires, and use it to rinse out the gauge between readings. Don't leave the gauge with Rimguard in it or it may be ruined. The same may be true for some other common liquids used in tractor tires.

I'm running ~15 psi in the rears on my Branson. Basically I let air out until the tread on the edges of the tire touch the pavement. It rides better than the 20 or so it came with from the dealer.

I have r-1's with tubes and liquid ballast.. But this is exactly how I adjust the rear pressure...if you pump them up with too much pressure it will only diminish traction when pulling ground engaging attachments.. or when in low wet areas

 

[ROUSTABOUT]

We have six tractors with liquid in the tires. Bigger than yours, we run 13 in rear. As long as yours stand up good, should be fine at 8 psi.

 

[masseyrider]

I don't use a gauge.
I do it by eye.
If I see one or both of the rears sidewalls are bulging I add some air until it "stands" up to the look I want.
I don't over inflate as it will ruin your ride on hard surfaces and taken to the extreme could blow them off the rim.
You lose traction also.
Never had any issues.

 

[SmallChange]

When I got my tractor it was brand new from the dealer with filled rears. Manual said 25 for the rears, but I measured 8. This was on a low pressure gage I bought from TSC. I forget what the gage range is, maybe 30. I never got the sense that they were bulging or soft. The fronts are very much smaller and run unfilled at much higher pressure, which I think is often the case when the tractor has a FEL.

 

[oosik]

At 8psi in your rear tires - might run the risk of rolling the tires off the rims.

I run 32psi in my front R-1's. I run 16 to 18psi in my Rim Guard loaded R-1 rear tires.

I use the standard "12 'O Clock High" technique if I ever want to check the pressure in the rear tires.

Otherwise - drive the tractor out on the gravel driveway. Make sure the rear tires show a full width chevron impression on the driveway.

 

[Gryz]

Thank you all for your input. I filled my front up to what the manual called for and will go to 14 or so in the rears.