Accurate Tire Pressure Measure with Dry Ice

<div class='quotetop'>QUOTE(Dudley @ Jul 13 2006, 10:47 PM) [snapback]286056[/snapback]</div>

:huh:

 

"In order to get good tire pressure, I need cold."

People have been setting tire pressure for 100 years without dry ice.

Just be consistent and measure it in the morning. Since no one knows what the "best" pressure is anyway, and experiment until they find their own personal compromise between comfort, handling, and mileage, the absolute number is meaningless anyway! Play with it until you ar ehappy, then measure it the next morning.

 

This has nothing to do with tire pressure, but the dry ice gave me an idea. What if you were to "mount" some dry ice under your car. The "fog" it produces would look really cool when you were stealthing around.

 

Remove the tire from the car.

Pack it in dry ice for about an hour.

Using the tongs, peel back enough dry ice to get at the valve stem.

Air the tire up to 42psi.

put the dry ice back over it, close it up for another 20 minutes.

Check the pressure again, top off if necessary.



Once you have a steady reading on your tire psi and it's at 42 (you want full tires for best mpg)... put it back on the car and repeat the process for the other 3 tires.

Now that you've used science to properly inflate all 4 tires, hit the road... For the best test, hopefully, it's about 95 degrees outside and you have some fresh blacktop to ride on at freeway speed. (60ish, we don't want to waste any gas).

Give this about 30 miles and then recheck your tire pressure. I'm betting (if the tires haven't blown yet) that your tire pressure is upwards of 90psi.

If the tires haven't blown yet, keep driving, they will. Once they blow, get a new set and start from the top with the dry ice.

For me.. I'm gonna stick with the 42/40psi at operating temperature. The key word being.. 'operating' temperature.

If, by chance you are going to be driving on dry ice for many miles, it does make sense to pack your wheels in dry ice to inflate them to 42psi. You'd get the reverse effect if you had 42psi tires on average day temperatures and then drove in an environment that is -150c. Your tires would either get too stiff to go flat, or they would go flat.

Let us know how the dry ice experiment goes... Wear your seat belt.

 

Some of us need new Social Directors! Brain surgery isn't this complicated. (At least the way I do it.)

 

"Cold" is defined as not having been driven on yet that day, not the temperature of dry ice. I think you will destroy your tires with dry ice.

Nate

 

<div class='quotetop'>QUOTE(naterprius @ Jul 14 2006, 12:29 PM) [snapback]286266[/snapback]</div>

Well said.

 

Ture pressure will vary throughout a regular day, even with the car sitting still. At the drag strip I will run 13 1/2 to 14 1/2 pounds, cold. Depending on the day I may have to add or subtract air between each round. Even having one side of the car in the sun can change the tire pressure which is why most people use vinyl tire covers.

The only way I am aware to minimize this problem is to use nitrogen instead of oxygen.

 

This thread is hillarious! That was the intent right?

How about a "cold" air intake for the use of your extra dry ice. AKA "Prius Bong!" :lol:
Mount a small cooler on top of your hood and route the air filter intake through the bottom of the cooler. Packed with dry ice, you could even keep a 'couple of cold ones in there.

Disclaimer: This poster does not condone the use of alcoholic beverages while vehicle is in motion.

 

Get free dry ice
place inside tires
inflate to desired pressure
enjoy frictionless tires due to temperature of tires.

Boy, ya gotta love these guys. They think of the weirdest things.

Ok guys repeat after me......

I will just check tire pressure before driving.
I will not do stupid things like use dry ice on tires.

repeat 50 times

 

Prius bong?! ... BRILLIANT!!! :lol:

-OR-

Load the dry ice in a cooler in the Prius and initiate a mobile wart removal service. Maybe have an imagineered giant wart mounted to the roof of the car.

With the dry ice on hand, you will be able to 'accurately' check tire pressure at any time, say at a stop light when nothing is happening anyway. This is way better than a Chinese Fire Drill (please, no offense intended to Americans of Chinese descent or affiliation or to any of our Chinese friends).

 

Pfft! Amateurs!

I submerge my tires in Liquid Nitrogen (-196C), NOT dry ice (-79.5 C). I'm still working on filling my tires in the dead of space (3 K or -270C), but that's proving to be more problematic than originally thought. If anyone knows of a launch vehicle that gets better than 50 MPG, I'd be much obliged.

Thanks.

 

oh my.

tires lose pressure when it gets cold out because the volume of gas changes with lower temperature. one of the variables in gas volume is temperature. so 42 psi in dry ice is going to be, like daron points out, much much higher at outside temperature in the summer.

take the dry ice, put it in a soda bottle, add water, cap tightly, shake, set in the street, and run. and don't touch with your bare hands or breathe the vapors.

 

If you need to drive to your air source at a gas station, etc:

First thing in the morning (no, not in Manitoba in the winter ) take pressure readings on all four tires and write them down and calculate how many psi each tire is under inflated from your ideal. If the tire reads 32 psi and you want 35 psi, the tire is deficient 3 psi.
Drive to your air source.
Starting with the tire which read closest to your ideal pressure, take another reading. If the new PSI reading is, for instance 38 PSI, pump it up another 3 PSI higher.
Move to the other tire.
Take a pressure reading if you want . . . you'll see the hot temperature shows the same difference . . . so this step is actually not necessary.
Fill the tire to the same 41 PSI you inflated the first tire to.

The comparatively little volume of new air you pump into the tire isn't going to make much of a difference in the temperature induced pressure inside the tires. Air is a poor conductor of heat, and the hot mass of the tires will keep the pressure up until the tires themselves cool down. (this is of course assuming you aren't inflating your tires with liquid nitrogen. :lol: )

I have use this method for years. The next morning when I checked the tire pressures, they are exactly right where I expected. I no longer bother checking the pressures the next morning. I know what the readings will be.

Of course with the Prius, you have two different pressures to consider – front and rear - but the concept is the same.

 

<div class='quotetop'>QUOTE(Sufferin' Prius Envy @ Jul 14 2006, 01:52 PM) [snapback]286331[/snapback]</div>

Uhm...what about the dry ice? :mellow:

 

The "Prius Bong" concept is actually utilized at drag races... It is fairly common practice for cars (in certain clases), with metal intakes to use ice to cool the air intakes immediately prior to crossing into the staging area for the burnout. Of course, to go along with the cold air, many people have "bottle warmers" for their nitrous...

 

Dudley, don't get upset by the tone of some of the replies to your question...some of us get cranky when we haven't been inside our cars for too long. We're really a, um, COOL bunch.
<div class='quotetop'>QUOTE(Three60guy @ Jul 14 2006, 11:13 AM) [snapback]286309[/snapback]</div>

Ok guys repeat after me... (ESPECIALLY daronspicher, alnilam, and, Three60guy--naughty boys--were you never newbies yourselves?)


There is no such thing as a stupid question
repeat 50 times

 

<div class='quotetop'>QUOTE(Rufaro @ Jul 14 2006, 02:41 PM) [snapback]286354[/snapback]</div>

This is true. However, there are things such as really, really ignorant questions (not to imply this is one of them), i.e., "Where's the 'Any' key?"

More discussion on "stupid" questions:
http://www.janisian.com/forum/archive/index.php/t-206.html