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Draining your compressor also prevents the tank from rusting out over the years. I've seen a few ruined that way.
 

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Too much of a pain for me to air up to 80 in the rears when I tow my 5er so I sacrifice ride quality when empty to be ready to tow at all times. My truck is not an everyday driver so I tolerate the harsh ride. I am at my limit when towing and want to make sure I am never tempted to tow with low rear pressures.

I also don’t bother with nitrogen and while I would use it if free as it is no word than normal air I think it is overhyped too. I have a car I track 3 or 4 times a year and after doing a pure nitrogen fill it still seemed to gain the same amount of pressure increase as normal air and I was airing down after my first few sessions anyway. Then the next day I aired back up with normal air and never bothered again. Maybe I would have gained more pressure with normal air as opposed to nitrogen but it still wasn’t worth it for me.


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Do I drain water from my air compressor(s) every now and then? Yes because I don't want excess water vapor in the compressed air, whether I'm using the compressed air for filling tires or using tools.
Yep, a good air dryer is money well spent. Draining the tank is obviously free.
I'm not that concerned about a minute amount of moisture in my tires (and it's much better than getting oil in them),
but my air tools get the cleanest air possible.
 
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Yep, a good air dryer is money well spent. Draining the tank is obviously free.
I'm not that concerned about a minute amount of moisture in my tires (and it's much better than getting oil in them),
but my air tools get the cleanest air possible.
I don't use my air tools for painting and I keep them oiled. So, draining is cheap and free.
I agree on the use of air in the street tires. I'm not too concerned with how much more they inflate from the moisture in the tires.
 

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I need to check it out, but I would've thought that air expands more than water when heated up. Maybe it's the other way around?
 

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It all depends on the amount of water in the tires. With water present inside the tires, the pressures will climb measurably higher and quicker if compared to tires with dried air or nitrogen filled tires. Once all the water has become vapor, the pressure increase becomes the same. If you were comparing two tires, one with water and the other with dried air, the tire with water when heated will have a pressure rise that's quicker and higher, compared to the dry tire, until all the water becomes vapor. After that, the pressure increase in both tires will be about the same, although the tire with water vapor will have a higher pressure.
 

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Interesting. I'll have to dig deeper and see if I can understand this. The little I saw during a quick check showed that air expanded quite a bit more than water.
And since the water content would (hopefully) be minute anyway, I figured that there would be no measurable difference.
 

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If your're in an aircraft, or race car, where the oxygen could be an issue from a fire standpoint after a crash, yes.
Other than that I can't see a single reason to use nitrogen.
Unless you are running pure o2 in the tires, that's the last thing to worry about in a crash, considering that you are totally surrounded by atmosphere with the same o2 content as what's in the tires.o_O
 

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Depends on where I fill my tires up, I guess. We have very little oxygen in the air here at home.
Anyway, I must've fallen for part of the nitrogen propaganda on that one.
 

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Interesting. I'll have to dig deeper and see if I can understand this. The little I saw during a quick check showed that air expanded quite a bit more than water.
And since the water content would (hopefully) be minute anyway, I figured that there would be no measurable difference.
The pressure increase could be several PSI, depending on tire temp and amount of water. The higher the temperature, the higher the pressure (it becomes exponential). On street tires - no big deal, as in "I don't care."
 

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Depends on where I fill my tires up, I guess. We have very little oxygen in the air here at home.
Anyway, I must've fallen for part of the nitrogen propaganda on that one.
Is nitrogen theoretically, technically preferable to atmospheric air in tires?........Yes.
Would I pay extra for it?........No
 

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The pressure increase could be several PSI, depending on tire temp and amount of water.
Regardless of any water content, I'm painfully familiar with how much the pressure changes with our common 50 degree swings in a day. Then there's the heat being generated from driving, and add to that what 5,000 foot elevation changes do to it.
Driving alone can easily amount to 8 psi or so on cold mornings.
 

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Regardless of any water content, I'm painfully familiar with how much the pressure changes with our common 50 degree swings in a day. Then there's the heat being generated from driving, and add to that what 5,000 foot elevation changes do to it.
Driving alone can easily amount to 8 psi or so on cold mornings.
Hopefully, you find this information helpful:
Put a plastic bottle with a small amount of water in the microwave with the cap on. Heat up the water and then shake it. The bottle will instantly expand. That is what is going on in the tires. If the water was on the verge of boiling and you shake it, the pressure would go way up and it might explode. That's how much the water vapor can add to the pressure in a tire when it get's really hot. It's not a big deal on street cars but at the track where tire temperatures can be much higher, the rise in pressure from water is exponential with high tire temps. Thus, the reason to use dry air (or nitrogen).

The key item I learned a long time ago is knowing the cold and hot pressures and try making adjustments to reduce the change in pressure (cold to hot psi). Here's an example: if the tire pressure while towing was 70 psi (hot) and was 65 PSI cold, you only had a rise of 5 psi from heat. If you had 60 psi cold, started towing and the pressure (hot) was 70 psi, you had an 10 psi rise in pressure, all from heat. That's more heat in the tires. The better cold pressure is 65 psi because less heat is generated, even though the pressure is the same when the tires are hot (70 psi in either case).

I know you kind of already get it because you know how much your tire pressure rise where you live, especially when there are crazy temperature changes. The dry air part is a variable that can be controlled but not worth the hassle on street tires.
 

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That is what is going on in the tires. If the water was on the verge of boiling and you shake it, the pressure would go way up and it might explode.
... the rise in pressure from water is exponential with high tire temps.
Well, I try my best not to get any tires up to 212 degrees. Also, I balance even my trailer tires, so the shaking is minimized.
Combined with our low humidity, I should be good to go.
 

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I knew there was a reason I have regular UHP tires on my fast car, and don't take it to more than 160. And that's obviously only for shorter bursts anyway.
It's bad enough t have to worry about the cops. I don't want to think about water vapor, too.
 

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If you're thinking about cops, you're not going fast enough.
That is a very good point, Zinga. And it's really when I only cruise along, at 100-120 in a 55, that I do.
At 140 and over there's no time to think about much else than the driving. Our roads aren't that straight.
 
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