Water Filled Tyres on a Hydrostatic?

[CPM]

You never fill the tires 100%. you get the stem at the top of the rim and fill it to that level. Filling it all the way can kill your tires because the fluid dosen't compress. Even then it doesn't slosh around like you think. Tractors don't start and stop that quick. There's not enough friction between the inside of the tire and the fluid to stir it up. I like having loaded tires. I think it is better than other types of weights, and the beat juice is heavier than water.

So, should I ask the dealer to fill them before delivery or is it something I could do myself?

 

[s219]

As far as a flywheel effect, which strains the driveline when starting and stopping, wheel weights would be way way worse than fluid in tires.

There is a slight amount of friction between the fluid and the tire that will want to "drag" the fluid around. If the tire was completely filled, this would eventually get the mass of fluid rotating and give it some rotational inertia. But given the very light forces in that drag, I don't think it would put much load on the driveline at all. However, tires are only about 75% filled, so the air gap at the top breaks up what could be a big rotating mass of fluid and very little fluid circulates around all the way (just drips basically). Instead, it's almost like the tire is rotating around a stationary pool of fluid.

Honestly, when I look at all the ways we deal with weight, traction, inertia, and rotating mass in vehicles, fluid filled tires are one of the most clever ways to do things in a tractor. It's like the best of many worlds.

 

[CPM]

As far as a flywheel effect, which strains the driveline when starting and stopping, wheel weights would be way way worse than fluid in tires.

There is a slight amount of friction between the fluid and the tire that will want to "drag" the fluid around. If the tire was completely filled, this would eventually get the mass of fluid rotating and give it some rotational inertia. But given the very light forces in that drag, I don't think it would put much load on the driveline at all. However, tires are only about 75% filled, so the air gap at the top breaks up what could be a big rotating mass of fluid and very little fluid circulates around all the way (just drips basically). Instead, it's almost like the tire is rotating around a stationary pool of fluid.

Honestly, when I look at all the ways we deal with weight, traction, inertia, and rotating mass in vehicles, fluid filled tires are one of the most clever ways to do things in a tractor. It's like the best of many worlds.

Thanks. Good to have a crash course in Computational Fluid Dynamics on a tractor forum. It makes sense though and very helpful!:thumbsup:

 

[George the Beagle]

So, should I ask the dealer to fill them before delivery or is it something I could do myself?

Either way works.

QLD=Queensland, right?

 

[CPM]

Either way works.

QLD=Queensland, right?

Yep, Queensland, Australia. "Beautiful one day, perfect the next" (so they say)

 

[MarkV]

CPM filling the tires with water is not hard and you can do it yourself if the dealer is going to charge for it. A search here on the forum will bring up numbers of threads that detail the process. In short there is a valve you can buy that attaches to the valve stem and a hose. The valve has a pressure release that will bleed air off as the water displaces the air. Here in the states the 10 dollar valve is found at tractor supply stores and some auto motive supply stores. Here is an example Installing Liquid Ballast in Tires | Gempler's

MarkV

 

[SPYDERLK]

As far as a flywheel effect, which strains the driveline when starting and stopping, wheel weights would be way way worse than fluid in tires.

There is a slight amount of friction between the fluid and the tire that will want to "drag" the fluid around. If the tire was completely filled, this would eventually get the mass of fluid rotating and give it some rotational inertia. But given the very light forces in that drag, I don't think it would put much load on the driveline at all. However, tires are only about 75% filled, so the air gap at the top breaks up what could be a big rotating mass of fluid and very little fluid circulates around all the way (just drips basically). Instead, it's almost like the tire is rotating around a stationary pool of fluid.

Honestly, when I look at all the ways we deal with weight, traction, inertia, and rotating mass in vehicles, fluid filled tires are one of the most clever ways to do things in a tractor. It's like the best of many worlds.

Excellent, factual description! Rotational inertia eventually developed in a "full" fluid tire is preserved when you stop, aiding take off a little in the same direction for a while [by internal circulating drag with the tire] ... but resisting takoff in other direction. The linear component of inertia should be the same solid or liquid for equal weight, but since rotational inertia builds up/changes slowly [or not at all] with fluid it should be easier to take off with fluid. ... :confused2: Any idea where the greater clutch wear with fluid anecdotes could have a factual base?
larry

 

[s219]

Any idea where the greater clutch wear with fluid anecdotes could have a factual base?
larry

Hard to say. I just ran the drag numbers for a general case using the tire size on my Kubota, assuming water as the fluid and 10 mph speed. A completely full rear tire would cause about 1.5 to 4 ft-lb of resistive torque due to drag, per tire, at full speed (so it's even less when starting out, since it would ramp up from zero). That seems like peanuts to me, and then figure it would be much lower for a partially filled tire with an air gap. Maybe it's more of an issue with huge tires or multiple tires, but I still can't see a whole lot of resistive torque from the internal fluid drag. Driving on soft ground likely causes way more rolling resistance than the internal fluid drag ever could.

The only thing I could figure is that maybe the anecdotes relate to greater traction and added mass. Increasing traction of drive wheels is known to put more stress on a driveline under loads -- the tires won't slip as much, so the driveline takes more abuse (and if there's a clutch, it might slip more to compensate). Put more mass in the mix, and of course the driveline has to deal with a higher load. But that's normally only an issue on dry pavement and at higher rotational speeds (ie, if you drop the clutch on an AWD car or when towing a load on a truck, something will slip or break in the driveline). I can't imagine how it would be an issue for most lower-speed tractor usage off road. Either way, the traction/mass effect would seem to affect wheel weights the same as liquid ballast, right?

 

[SPYDERLK]

It had to do with "tractor pulls" ... maybe hi speed spinning. Acceleration of fluid away from the deformed contact patch could be significant in a fast spin. May take longer for the clutch to grab? ... or prevent a full grab.:confused3:

 

[SockPuppet]

It had to do with "tractor pulls" ... maybe hi speed spinning. Acceleration of fluid away from the deformed contact patch could be significant in a fast spin. May take longer for the clutch to grab? ... or prevent a full grab.:confused3:

I really don't see where what goes on in a pulling tractor tire has much comparison to what's happening in a regular tractor tire doing regular tractor work. The amount of HP, the type and size of tire being used, the way the power is applied to the rear wheels, what happens when the tires slip are all significantly different with a pulling tractor.

A lot more information is needed to analyze what's going on in high performance applications. With that said, it would seem that taking out the clutch would be the result of too much traction combined with too heavy a foot.