Leaky Wheels

[have_blue]

I've been using a friend's Kubota M125X, and both front wheels sprung a leak. They both leak where one of the "spokes" are riveted or spot welded on. (can't really tell which). Nothing in the documantation says, but the dealer says the big ag tires are tubeless. The valve stem doesn't tell me clearly whether they're tubeless of tube type, so let's assume tubeless.

The tractor is about 18 months old, and still under warranty. The dealer will fix or replace the wheels. A lot of questions pop into my head. Is this comon? The owner issists on tunning the front tire pressure at 25psi, and they call for 18psi. Could this cause the leaks, or is this more likely a factory defect? Would an inner tube be a good fix for them, or will the loose spokes gradually get looser?

Many thanks,,,

http://i31.photobucket.com/albums/c394/bobad/Picture013.jpg

 

[PineRidge]

Bob don't know if your situation is common or not but a tube would be a good idea, and a tube and some tire sealant like Slime or Multi-Seal would be the end of your problems for a long time to come.

What happened to your New Holland, did something break?

 

[have_blue]

Bob don't know if your situation is common or not but a tube would be a good idea, and a tube and some tire sealant like Slime or Multi-Seal would be the end of your problems for a long time to come.

What happened to your New Holland, did something break?

Hi PR. Thanks for the advice. Yes, tubes would be the end of the problem, unless the wheel "spokes" get looser and looser. I bet that tire sealant would have worked perfect too.

But,, we already herded the big Kubota to the dealer this morning. We're hoping Kubota will spring for new wheels, or at the least inner tubes and labor. Wheels shouldn't leak with under 200 hours, and the Kubota's owner is pretty chapped off.

I'm digging a 1.5 acre pond, and getting a lot of seat time in the 125hp Kubota and a 90hp JD dozer. My little NH is sitting this one out.

The heavy equipment is very nice and all, but there's nothing like my little NH for doing certain chores. It can run rings around the big stuff.

 

[Soundguy]

My guess is the dealer will either swap rims.. or mig the leak up.

Tubes would work as well.

The difference between 18 and 25 psi did not cause the issue.. besides.. if you hit a rock or bounce, the tire pressure may spike internally anyway..

Soundguy

 

[schmism]

if you hit a rock or bounce, the tire pressure may spike internally anyway..
Soundguy

unless you change the volume of air the tire holds that would be impossible.

 

[Soundguy]

And that's exactly what I was refering to.. a change in container volume due to tire distortion.

Ever see a hand strength measuring device where they ask you to squeeze a hard rubber ball, and then watch the dial move, and record the number?.. it's pretty easy to decreas the volume of a hollow form by deforming and folding.

Soundguy

 

[sandman2234]

Or run a heavily laden tractor trailer over a curb and watch the sidewalls burst? Same thing with a little more extreme.
David from jax

 

[Soundguy]

Yep...

Soundguy

 

[schmism]

And that's exactly what I was refering to.. a change in container volume due to tire distortion.

Ever see a hand strength measuring device where they ask you to squeeze a hard rubber ball, and then watch the dial move, and record the number?.. it's pretty easy to decreas the volume of a hollow form by deforming and folding.

Soundguy

ok few things hear...

a tire is a gass filled rubber container able to change its shape but not its volume (with in reason). a hard rubber ball is a solid. meaning you can sweeze its shape and affect internal pressure. your correct that its easy to change the volume of a squishy shape, but you have to apply that pressure evenly on all sides for that to work, else your squishy shape is going to buldge out on sides that dont have that pressure applied.

a heavly loaded tire in contact with a hard surfce changes shape because thats the only way it can continue to support the load on the wheel. its Pounds per sq inch. so if i reduce the area of contact (with an edge of curb) the only way to maintian the load is to spred it out more so the tire changes shape to create more surface to bear on ..

an example is good

say normal resting weight a) on tire pressure b) on a 2x3" sq patch of rubber.

roll up to a curb with edge contact of 1" then the tire has to get wider to support the load... it has to "squish" to 6" wide (the example is a bit over simplified because as you squish the tire it makes more contact with the curb so the "contact" area of what was org 1" grows as well as the width)

another way to look at it, 2x3" patch of rubber supports a given load at a given pressure. you load the FEL up and now look at the tires. they squat more. why? well in order to support the larger load they had to create more surface area. load(lbs) = area(sq inchs) * pressure. (lbs/sqinch)

still dont belive me, at home tonight, measure your pressure to the nearest pound. (needs to be accurate) then load up the FEL and measure it again.
you wont see an increase in the pressure.

to get all mathy on ya check out the law that is the reason behind the above examples. its called Boyles law Boyle's law - Wikipedia, the free encyclopedia

Boyle's Law states that the product of the volume and pressure of a fixed quantity of an ideal gas is constant, given constant temperature. Expressed mathematically, the formula for Boyle's law is: p V = k

NOTE: (while air isnt an ideal gas you can consider it one for our every day lives. also note that should you heat or cool your tires the pressure WILL change inside)

 

[DieselPower]

still dont belive me, at home tonight, measure your pressure to the nearest pound. (needs to be accurate) then load up the FEL and measure it again.
you wont see an increase in the pressure.

to get all mathy on ya check out the law that is the reason behind the above examples. its called Boyles law Boyle's law - Wikipedia, the free encyclopedia

Boyle's Law states that the product of the volume and pressure of a fixed quantity of an ideal gas is constant, given constant temperature. Expressed mathematically, the formula for Boyle's law is: p V = k

NOTE: (while air isnt an ideal gas you can consider it one for our every day lives. also note that should you heat or cool your tires the pressure WILL change inside)

Ummm, I don't think that would hold true. As you apply more preasure to the wheel the preasure WILL increase. This is afterall how a air COMPRESSOR works. It compresses the air by decreasing the volume of the cylinder. Same with a tire. You add weight to a tire and the preasure will increase. As the tire is crushed by the extra weight it can only expand so much. It will not be a drastic change because a tire is made of rubber and can expand to a point but it will rise.

To prove the point I even went out back and checked the tire preasure on a loaded 18 wheeler I have on my lot. With out a trailer the rear tire preasure was 121.2 PSI. With a loaded 53 foot trailer (close to 40,000 pounds as it set's) on the 5th wheel the preasure went up to 122.4 PSI. I used my Snap On Vantage graphing meter with a digital preasure gauge that is accurate to 1/100 of 1 PSI to take the preasure measurement.

Another example would be to overload a tire to the point that it explodes. Why does it explode? Because the preasure in the tire increases to the point the tire can no longer retain the increased preasure.