Rough ride with filled/loaded tires??

daTeacha · Jun 15, 2006

I had a small Kubota B7100 with 15" rears. After loading those tires to 75%, the ride was much more harsh.

Pressure will be a major factor. With a loaded tire, 75% of the interior volume is now filled with incompressible fluid and only 25% with compressible air. Driving over an object will spike the air pressure faster than with the unloaded tire.

I just added about 130 lb of homemade wheel weights to my tractor. Haven't done enough with it yet to notice if there is a major increase in stability or not. I run 9 lb. of pressure in the rears (24" rims) with 900 lb. on the 3 point. The manual says only 18 lb. max. in the back tires, although the tires are stamped for 35. I did notice that running the rears at 17 psi on new limestone showed that only the center half of the rears was actually contacting the stones. With 9 lb, I get full contact.

MMM · Jun 15, 2006

The only real difference I noticed is at road speed. The tractor oscillates side to side with fluid and doesn't whrn dry.High speed braking tends to cause pucker also. People are real prone to be vehicular iidiots arounf a tractor

djradz · Jun 15, 2006

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I'm not sure I agree. Although the volume for the air is much smaller, it is still at the same pressure. Using the old physics equation, PV=mRT, with mRT unchanging, leads one to P1V1=P2V2, with 1 being the before the bump or spike or whatever pushed on the tire and 2 being the state during. Therefore, unless the volume change significantly during state 2 (during the bump/spike, whatever) which is not very likely unless a huge push/deformation of the tire occurred, the tire would stay essentially in the same shape and the pressure essentially unchanged - so no significantly rougher ride. Possibly, with very small tires, where the remaining volume becomes quite small, you will notice a difference because the volume becomes something on the order of only a few gallons.
I think the rougher ride, or at least the perception of one may come just as much from the fact that on many tractors, you're now moving many more hundreds of pounds of material.

3RRL · Jun 15, 2006

It's funny how the difference can be interpreted. In my case, after filling, my perception was not so much the ride was "rougher" but rather more "riged"... or more "stable" or more "solid". More like when you set your trucks's off road suspension stiffer (if you have that ability). So IMO, because the different ride is a result of the action taken, I prefer to consider it more "solid".... but I guess it can be interpreted as "rougher". /forums/images/graemlins/confused.gif

firemanpat2910 · Jun 15, 2006

Rob thats a good description of the change in mine also.
I think it feels much better.

GeneD14 · Jun 16, 2006

I have collected antique tractors for several years and I have had to haul them hundreds of miles by trailer on occasion. If a tractor's large rear tires have air only on certain stretches of highway (like I-94 in MI ) the tractor will start bouncing due driving over equally spaced joints in the concrete. After a few minutes I have to slow way down to get it under control.
When I haul a tractor with filled tires or a crawler with steel tracks there is almost no bouncing at all.

daTeacha · Jun 18, 2006

To me, a rough ride means that I feel a 2" stick when I drive over it, or the stones in the driveway are noticable when prior to loading they weren't. It was very noticable to a guy with a herniated disc or two in his back, especially since adding the ROPS and setting the seat back to fit my body essentially put the seat solidly on the frame of the tractor. Not that those little rubber bushings provided much cushion in the first place!

The 'bota had only 8 x 15 inch rear tires, so the air volume after filling was pretty small -- I'd guess 2 gallons or so, if that. I also didn't check to see what pressure the tire store set them at, so they might have 30 pounds or more in there.

My DX, with 9 lb of air in 24" tires and a suspension seat, feels like a dream compared to the 'bota. Even so, I made wheel weights instead of loading the tires.

I get some harmonic bounce when working with the back blade on the driveway and the loader is mounted. I'll have to try taking the bucket off to see if that reduces it. I don't know if there's a cure for that tendency with soft tires and no springs.

MikePA · Jun 18, 2006

daTeacha said:
Not that those little rubber bushings provided much cushion in the first place!

Sounds like you're a candidate for a suspension seat that can be adjusted for the weight of the driver and the terrain. My NH TC25D came with one and I love it.

Doc_Bob · Jun 18, 2006

MikePA said:
Sounds like you're a candidate for a suspension seat that can be adjusted for the weight of the driver and the terrain. My NH TC25D came with one and I love it.

The suspension seats are great. It is a NH feature that I really appreciate. Also, many of the NH have the ramp height adjustment. With my long legs, a real nice touch.
Bob