Ballast rim guard and proper inflation

[Todd727]

Too many people confusing volume with pressure. A scuba tank with no pressure has the same volume as the same tank pressurized to 3000 psi.

Too many people that didn't pay attention in school to Ideal Gas Law, PV=nRT.

 

[Texasmark]

I'm glad I saw this comment. I have a loaded rear tire with a slow leak. The last time I re-aired the tire, I noticed that fluid was slowly bubbling out of the stem. To me, this means that the stem core is not sealing properly. I was going to jack up that side in the rear and screw out the stem to replace it, but your comment suggests I could end up with a big mess (and one unloaded tire!) if I do this.
Is the only solution to remove the fluid, do the stem replacement, then refill??

Over (your normal fill) inflate the tire. Have the replacement core/stem ready, make the exchange quickly. Reduce the pressure to your normal level.

 

[Texasmark]

I think we are getting into semantics here. PV = nRT is well defined in the www Wikipedia site for the ideal gas law.

Having a gas tank with a certain cubic inch (for a metric) volume can have 14.7#/sq in or 3k#/sq in or anything in between internal pressure. Difference is the volume of air you put in that volume of the tank. Simply put, a scuba tank sitting empty is filled with gas, ambient air. It has a certain volume at atmospheric pressure (14.7 # sq in at sea level). If that tank is pressurized to 3000# it has 3000/14.7 x the volume of air it had originally, hidden as increased pressure.....PV is a constant. The idea is to store lots of volume in a small space so you use pressure.

On my tires, I am looking to use weight to my advantage in softening the ride which is the fill.

I am also using the PV (being a constant) relationship so that I have adequate volume to keep the pressure spike low when I hit a bump, and with my soon to be installed 4 ply, soft sidewall tires, I am attempting to take sidewall stiffness/resistance out of the equation. On the sidewall not contributing to the stiffness whomever said that needs to rethink what they said. When is the last time you saw a deflated balloon in any shape other that flat as compared to what happened the last time you sat on a 10-12 ply un-mounted tire on end and it retained it's shape.

Ideally I'd leave the tire dry and add a weight. That would give me maximum weight and maximum volume (to absorb max impact with minimum pressure differential)....best of both worlds. Seen any weights for a 25 hp compact tractor lately? If you did imagine what they'd cost? In retrospect, probably would be cheaper than this pair of 4 plies I just bought for $600.

But I have used weights before, 4 ea 150# weights on the rears of my 4230 JD and they were a pain....kept the tire to hub mounting bolts working loose and any kind of tire repair was a joke. Had a pair of 85# on the front of my 2000 Ford and you couldn't steer worth a hoot (manual steering)....tire repair a problem there too. Course liquid fill is another pain, but you can drain it out and do what you need to do and put it back in....and it's available.

Heck it's 2 AM. Rearing to go for tomorrow. Can't sleep. Too early for my beloved morning coffee (....shop on here with folks like you). Got to do something to get sleepy so I can go back to bed so I get on here and jabber. Not really a problem as being retired one has "earned" the right to get up when you please and take a nap in the afternoon if one feels like it.

It worked. Feeling sleepy so it's back to bed. Thanks

 

[Gary Fowler]

It doesn't matter if the air is hot or cold, high pressure or low pressure, the air itself has close to no strength to support anything. If air could support stuff, things wouldn't fall if you drop them .

If this were true, then an airplane or bird couldn't fly. Think about how a million pound 747 goes up rather than staying on the ground and then explain how air doesn't support anything. By the way, hot air doesn't support as much as cold air when it comes to flying unless you are talking about a hot air balloon. Hot air balloons work because the hot air inside the balloon displaces the more dense cold air around it which causes the air in the balloon to rise thus it is the cold more dense air supporting the weight of the balloon and passengers and not the hot air inside the balloon.

 

[4570Man]

If I was wanting to pull a valve stem on a loaded tire I would lift up the tractor until the rubber just started to deflect. I want the weight of the tractor supported, but the weight of fluid still on the ground if that makes sense.

 

[Billrog]

Bring the stem up to 12 o clock jack the wheel off the ground let the air pressure out then change the valve stem and pump the tire back up.

 

[ovrszd]

Bring the stem up to 12 o clock jack the wheel off the ground let the air pressure out then change the valve stem and pump the tire back up.

His fear is that with a tubeless tire it will unseat from the rim. And he's correct to have that fear.

4570man's suggestion is as good as it gets. I'd have my replacement stem ready. Don't drop it and let it roll across the shop floor......

 

[sailfast]

His fear is that with a tubeless tire it will unseat from the rim. And he's correct to have that fear.

4570man's suggestion is as good as it gets. I'd have my replacement stem ready. Don't drop it and let it roll across the shop floor......

Yep. And still rotate to 12 and jack up to some point with the tire on the ground, weight of fill on ground but weight of tractor off.
Jack it up just a bit, watching deflection

Force is square inches x #/ inch squared. Same formula as a hydraulic cylinder force acting on a log splitter or what have you.
You have many square inches so it only takes a few # to support/equal the opposing force....the unit.

I think we are getting into semantics here. PV = nRT is well defined in the www Wikipedia site for the ideal gas law.

Having a gas tank with a certain cubic inch (for a metric) volume can have 14.7#/sq in or 3k#/sq in or anything in between internal pressure. Difference is the volume of air you put in that volume of the tank. Simply put, a scuba tank sitting empty is filled with gas, ambient air. It has a certain volume at atmospheric pressure (14.7 # sq in at sea level). If that tank is pressurized to 3000# it has 3000/14.7 x the volume of air it had originally, hidden as increased pressure.....PV is a constant. The idea is to store lots of volume in a small space so you use pressure.

On my tires, I am looking to use weight to my advantage in softening the ride which is the fill.

I am also using the PV (being a constant) relationship so that I have adequate volume to keep the pressure spike low when I hit a bump, and with my soon to be installed 4 ply, soft sidewall tires, I am attempting to take sidewall stiffness/resistance out of the equation. On the sidewall not contributing to the stiffness whomever said that needs to rethink what they said. When is the last time you saw a deflated balloon in any shape other that flat as compared to what happened the last time you sat on a 10-12 ply un-mounted tire on end and it retained it's shape.

Ideally I'd leave the tire dry and add a weight. That would give me maximum weight and maximum volume (to absorb max impact with minimum pressure differential)....best of both worlds. Seen any weights for a 25 hp compact tractor lately? If you did imagine what they'd cost? In retrospect, probably would be cheaper than this pair of 4 plies I just bought for $600.

But I have used weights before, 4 ea 150# weights on the rears of my 4230 JD and they were a pain....kept the tire to hub mounting bolts working loose and any kind of tire repair was a joke. Had a pair of 85# on the front of my 2000 Ford and you couldn't steer worth a hoot (manual steering)....tire repair a problem there too. Course liquid fill is another pain, but you can drain it out and do what you need to do and put it back in....and it's available.

Heck it's 2 AM. Rearing to go for tomorrow. Can't sleep. Too early for my beloved morning coffee (....shop on here with folks like you). Got to do something to get sleepy so I can go back to bed so I get on here and jabber. Not really a problem as being retired one has "earned" the right to get up when you please and take a nap in the afternoon if one feels like it.

It worked. Feeling sleepy so it's back to bed. Thanks

 

[rd_macgregor]

4570man's suggestion is as good as it gets. I'd have my replacement stem ready. Don't drop it and let it roll across the shop floor......

This was the first image that came to my mind when I read the suggestion...I know myself well!