Filled rear tires characteristic...

Mowbizz · Jul 31, 2014

My BX25D has filled rears and I have just begun to experiment with letting some air out to soften the hard ride of the seemingly over-inflated tires. I checked the pressure before and found them to be rather high at over 35 pounds...started releasing some air and settled on approx. 20-22 pounds in each rear tire. I kind of expected to see the tire "flatten" a little but when I'm sitting on the tractor and looking down at the rears, it appears that they are still over inflated, to the eye anyway. In other words, there is no bellying out of the bottom (like a radial tire) but just the opposite, they appear to be still over inflated. I hope I'm describing this so you can understand what I mean.
Point me in the right direction by what experience you have with filled rears and tire pressure...THX!
Perhaps these pics will explain what I'm talking about...and no comments about the funky toes please!! :laughing:

GPintheMitten · Jul 31, 2014

You need some air to soften the ride. If the tire is completely filled with liquid, there is no air to compress when you roll over a rock or other uneven surface because liquid doesn't compress.

I would start by trying to figure out how full the tires are. I think you want a maximum of 90% and probably better to be a little less. Maybe someone else knows the optimal liquid fill rate.

Then tune the amount of air pressure.

But I don't know the optimal air pressure.

GolfAddict · Jul 31, 2014

I've always heard 75% liquid. As far as pressure, I fill my turfs to 20 as labeled on the tire side wall, and they look pretty much the same as your pictures.

jlgurr · Jul 31, 2014

Does anyone know if the tire pressure should be different when they are loaded vs. when they are unloaded?

oosik · Jul 31, 2014

My rear tires are 75-80% filled with Rimguard. I run the tire manufacturers recommend pressure - 18 psi. They don't look any different than those at the dealer with only air in them. They do have a more "pooched out" look than yours. Mine are radials and Kubota recommends a max of 75% fill on fluid filled tires. There is no spec difference between radial & bias-ply tires. If yours are bias-ply they will tend to have stiffer side walls than radials and will stand up straight & tall even with reduced pressure. Do as GPintheMillen recommends. Rotate your tire so the valve stem is at either 10am or 2pm position. Let a little air out of the stem. If there is no fluid blowing out then your tires are properly filled. If fluid comes out then they may be overfilled. Rotate stem to 11am or 1pm position - if fluid still comes out, you are a little overfilled and may want to remove some fluid. Anyhow, when you have done all this rig-a-maroe run the tires at recommended pressure in your OP manual. With the tires properly filled with fluid & air - the ride you get is all that can be expected. Do not run air pressure below what it says in your OP manual. There is the possibility you could roll the tire off the rim. Do not run the pressure at what I indicated above - thats for my situation and not yours.

If you still want a softer ride - get a foam pad for the seat or look into an air ride seat.

George2615 · Jul 31, 2014

No, air pressure should be what is recommended or what gives you à good ride with the most traction. 18-20# should be fine.

oosik · Jul 31, 2014

My OP manual recommends 18 psi for my rear tires - loaded or dry.

kuboman · Jul 31, 2014

75% is absolute maximum for fluid. If they are radial they are recommending 50% fill now. Tire pressure should be set so the tread of the tire is flat on the ground and with little sidewall flex for a bias tire. Radials should have the bulge but not to the point that the bulge will create sidewall cracking.
Unless you are packing heavy loads on the 3pt I would think even 18psi would seem hard.

Mowbizz · Jul 31, 2014

oosik said:
My rear tires are 75-80% filled with Rimguard. I run the tire manufacturers recommend pressure - 18 psi. They don't look any different than those at the dealer with only air in them. They do have a more "pooched out" look than yours. Mine are radials and Kubota recommends a max of 75% fill on fluid filled tires. There is no spec difference between radial & bias-ply tires. If yours are bias-ply they will tend to have stiffer side walls than radials and will stand up straight & tall even with reduced pressure. Do as GPintheMillen recommends. Rotate your tire so the valve stem is at either 10am or 2pm position. Let a little air out of the stem. If there is no fluid blowing out then your tires are properly filled. If fluid comes out then they may be overfilled. Rotate stem to 11am or 1pm position - if fluid still comes out, you are a little overfilled and may want to remove some fluid. Anyhow, when you have done all this rig-a-maroe run the tires at recommended pressure in your OP manual. With the tires properly filled with fluid & air - the ride you get is all that can be expected. Do not run air pressure below what it says in your OP manual. There is the possibility you could roll the tire off the rim. Do not run the pressure at what I indicated above - thats for my situation and not yours.

If you still want a softer ride - get a foam pad for the seat or look into an air ride seat.

I'll try the 10 and 2 trick...seems reasonable. I have already let out some air so chances are I am close to what they should be at...next is to see how much rimguard is inside. Thx!

rScotty · Jul 31, 2014

Mowbizz said:
I'll try the 10 and 2 trick...seems reasonable. I have already let out some air so chances are I am close to what they should be at...next is to see how much rimguard is inside. Thx!

How do you tell how much rimguard is inside?
BTW, I run my rear tires at about half - sometimes less - than the recommended pressure in order to enjoy a softer ride. Been doing that 40+ years on half a dozen tractors - two with 4wd turfs.
rScotty