Tire pressure for L3901

[kylster]

Hey guys... I'm new to tractors and was hoping to get some advice on tire pressure. I have a 2020 L3901 with loader and backhoe. The manual appears to recommend 30 psi for the front, but knock it up to 45 psi since I have a loader. The rear has ballast liquid and the manual appears to indicate 30 psi also. The problem I am having is I asked a service tech at the dealer what the pressures should be (noting the loader and backhoe), and he indicated 30 psi for the front and 10 psi for the back. Am I missing something or does he not know what he is talking about? Also, FYI he said to just change the filters at 50 hours and leave the super UDT2 in until about 200 hours. This also appears to be in conflict with the manual.

Any thoughts would be appreciated.

Kyle

 

[ayak]

My tires are R4s, so your mileage may vary but with a 3301, I have essentially the same setup (filled rears), and run my BH77 all the time with 25-27 in the rears and 25-30 on the fronts (approaching 30 only when I have some heavy FEL work to do with a full bucket of limestone or some heavy grapple work).
Higher pressure than that and I’ll get the tar kicked out of me (or at least wish I was wearing a cup).
You’ll definitely have better traction if you lower the pressure as more lugs will be in contact but I just can’t make myself go lower than 20 on those rears.
I did both filters and UDT2 fluid at 50hrs, but that’s just me. I had no interest in trying to worry about how fast the fluid would fly out of the ‘hydraulic’ filter so I decided to do that at the same time as the HST and UDT2, and then go to a 400hr schedule for the hydraulic filter and fluid, and 200hr schedule with the HST filter (not too much is lost on that side).

 

[Henro]

Hey guys... I'm new to tractors and was hoping to get some advice on tire pressure. I have a 2020 L3901 with loader and backhoe. The manual appears to recommend 30 psi for the front, but knock it up to 45 psi since I have a loader. The rear has ballast liquid and the manual appears to indicate 30 psi also. The problem I am having is I asked a service tech at the dealer what the pressures should be (noting the loader and backhoe), and he indicated 30 psi for the front and 10 psi for the back. Am I missing something or does he not know what he is talking about? Also, FYI he said to just change the filters at 50 hours and leave the super UDT2 in until about 200 hours. This also appears to be in conflict with the manual.

Any thoughts would be appreciated.

Kyle

With liquid in the rear tires things changed a little bit because the net volume of air is much smaller, and pressure increases much quicker when the tires deform. So in my mind it makes sense that with liquid in the tires if you wanted things to be similar to a tire with no liquid inside it, you would run lower pressure.

The front tires on both my tractors are foam filled since they punctured easily. I have no idea how to compare them to air filled tires. But I would guess they compare to front tires that are inflated to close to the maximum recommended pressure.

As far as changing the hydraulic fluid at 50 hours, the technician is probably giving you a good practical advice, but why risk it? If you don’t change the fluid you save some money. And PROBABLY it makes no difference. But a new tractor is a significant expense, and if you’re planning on keeping it for a long time why take any risk, in addition to you might take by owning it to begin with?

 

[Jchonline]

My manual has hydro and oil filters with oil only at 50 hours. Then 200 for the hydro fluid. Just go with exactly what your manual says for maintenance and be sure to document it in the manual or a separate log (date/time what was done, etc).

 

[GeoHorn]

The recommended pressures for filled and unfilled tires are the same. Just because the volume of air is less does not change the pounds-per-square-INCH of pressure within.

The Owners Manual should be consulted for your tire pressures, Kyle,...but your dealer sound as if he’s in the ball park on his advice.

 

[Henro]

The recommended pressures for filled and unfilled tires are the same. Just because the volume of air is less does not change the pounds-per-square-INCH of pressure within.

The Owners Manual should be consulted for your tire pressures, Kyle,...but your dealer sound as if he’s in the ball park on his advice.

True if the tractor sits unused. But the dynamics are different during use when the tires are subjected to external forces that deform them…when volume changes, gas pressure changes.

In a tire, when deformed, volume the air resides in will likely decrease (if the tire stays on the rim) so pressure will increase at that moment in time. This is because the liquid in the tire is basically uncompressible, so the net effect is reduced size of the air pocket.

 

[NCL4701]

Manual for mine is filter only for hydraulic and HST at 50hr. I’d go with whatever your manual says as being what is necessary. If changing the fluid isn’t required and you change it, it shouldn’t hurt anything other than your bank account.

I started with 30psi in loaded R4 rears from dealer. Rode slightly better than steel wheels and traction was less than ideal. Dropped to 20psi which improved ride and traction.

Fronts are not loaded. Still at 35psi because I use the loader quite a lot.

The tire pressures listed above aren’t necessarily recommendations, that’s just where mine are set.

 

[GeoHorn]

True if the tractor sits unused. But the dynamics are different during use when the tires are subjected to external forces that deform them…when volume changes, gas pressure changes.

In a tire, when deformed, volume the air resides in will likely decrease (if the tire stays on the rim) so pressure will increase at that moment in time. This is because the liquid in the tire is basically uncompressible, so the net effect is reduced size of the air pocket.

Yes, Henro... exactly as it does in an Un-filled tire....the air volume will be reduced and the pressure momentarily increased...and that is why the filled tire should only be 3/4 filled with liquid..... to allow the air to act as a cushion.

 

[B2710]

My advice is to experiment with pressures.

I run 10 -12 psi in my R4 rear tires on all my tractors, if I run what the manual states, maybe a 1/4 of the tread is on the ground and it is bouncy and rough to ride on. I started with factory pressures on many but lowered them till I was happy.

Just when thru the same thing with the wife's new LX3310 with R14 rear tires, factory calls for 32 psi but wow, the tire looks like a balloon with only the center of the tread on the ground. I am now at 15 psi and feel this is about right for tread on the ground and ride for the R14s.

The R14s have a softer feeling sidewall and I likely will not lower pressure much more than 15 psi but with R4 on all my other tractors, I have no problem with 10 psi all day long.

 

[kylster]

Thanks for all the responses! Clearly, the tire pressure question is not something that you always go by the book. I do think, however the wisest thing to do regarding the hydraulic fluid is follow the manual, since deviating may cause any future warranty issues to be voided.

Thanks again everyone...... Kyle