Tire Pressure Warning System

rickm · **Posted:** Sun Nov 25, 2007 1:52 am

Yesterday and today, I'm getting a tire pressure warning when the vehicle is cold. After I drive for a mile or so, the light goes out.

When I first saw it, I thought maybe the spare was low for some reason, but since it goes out after I drive for a bit, I guess it's one of the 4 wheels in use. They don't look low, or one doesn't appear lower than the others. I gotta find my tire pressure guage now.

SoDakJeep · **Posted:** Sun Nov 25, 2007 2:17 am

cold air less air pressure tires warm up and your back at the right psi

Guest · **Posted:** Sun Nov 25, 2007 11:26 am

the light goes on when the tires are more than 10% out of the recommended pressure, which would be below 30 or above 36 psi. it's gotten cold, so pressure decreases;)

rickm · **Posted:** Fri Nov 30, 2007 3:41 am

ok, so I think I solved the problem today.

I took my KK over to Costco and had them deflate all the tires, including the spare and refill them with nitrogen.

We'll see what happens tomorrow morning when it's cold.

Oh, and they charged me $0.00 for the service.

Did I mention how much I like Costco?
:lol:

rickm · **Posted:** Sat Dec 01, 2007 3:38 am

looks like the nitrogen did the trick. No warning lights today

Diggerfreek · **Posted:** Sat Dec 01, 2007 4:03 pm

rickm wrote:

looks like the nitrogen did the trick. No warning lights today

Thats sweet that they did it for free.....now the next question is whether or not your gas mileage goes up a bit :?:

Guest · **Posted:** Sat Dec 01, 2007 6:19 pm

it won't. the benefits of nitrogen are negligable.

rickm · **Posted:** Sun Dec 02, 2007 12:27 am

except for no expansion and contraction like air, I wouldn't expect any benefits using nitrogen?

Why would you think I should get better mileage, because the tires are at correct pressure now?

Diggerfreek · **Posted:** Sun Dec 02, 2007 12:59 am

rickm wrote:

except for no expansion and contraction like air, I wouldn't expect any benefits using nitrogen?

Why would you think I should get better mileage, because the tires are at correct pressure now?

being at the correct pressure was what i had in mind, specifically when they are warm and possibly riding on the middle of the tire instead of the whole tire.....On a side note, it may even extend the life of a tire do to it not expanding and contracting...it's just a thought...On most CAT machines from the fectory, the tires are nitrogen filled to combat heat...On scraper, like a 623 or 627, there is a passage with in the rim that is filled with coolant as these tires have a problem with heat. when they heat up, they blow up and now your out $15,000.. As i said, just a thought

rickm · **Posted:** Sun Dec 02, 2007 2:11 am

ok, I gotcha, we'll have to see what happens. Problem is, I haven't been keeping real good track of gas mileage. However, I do know one thing. I get quite a few more miles per tank than I did on my KJ, and it's the same size fuel tank.

Guest · **Posted:** Sun Dec 02, 2007 10:28 am

rickm wrote:

except for no expansion and contraction like air, I wouldn't expect any benefits using nitrogen?

Why would you think I should get better mileage, because the tires are at correct pressure now?

Nitrogen will still contract and expand, just not as much.

rickm · **Posted:** Sun Dec 02, 2007 2:50 pm

ThunderbirdJunkie wrote:

rickm wrote:

except for no expansion and contraction like air, I wouldn't expect any benefits using nitrogen?

Why would you think I should get better mileage, because the tires are at correct pressure now?

Nitrogen will still contract and expand, just not as much.

yeah, I knew that. We used that stuff to pump up static brake pressures on aircraft arresting systems when I was in the Air Force. In fact, we had to use "oil pumped" nitrogen, because it was dry, unlike normal nitrogen.

shimmy · **Joined:** Tue Nov 13, 2007 10:20 am **Posts:** 6

Nitrogen and dry air will expand the same amount. The formula is called the ideal gas law. pV=nRT. p is pressure, V is volume, n is the amount of the gas, R is a constant and T is temperature. So the only variables are pressure and temperature. If the temp goes up, so does the pressure. Period, end of story.

The only difference is the slight amount of moisture in the air. That can expand or contract a bit more than a dry gas. The "experts" feel that nitrogen is better used because it is a larger molecule and might leak out less therefore keeping your tires better inflated..

If you keep an eye on your tire pressure, there is no benefit to running nitrogen except for the cool little green valve caps.

rickm · **Posted:** Mon Dec 03, 2007 1:28 pm

holy moley, that's a lot of information. Are you saying that the military misled me all those years? :lol:

I'm just kidding, but we did use oil pumped nitrogen because of the moisture content.

Compressed air has a lot of moisture in it, unless it's gone through a dehydrator.

shimmy · **Joined:** Tue Nov 13, 2007 10:20 am **Posts:** 6

Compressed air can have a lot of moisture in it. That's why compressors have the drains on the tanks. I had a job, a LONG time ago in a machine shop. My first duty of the day was to go in and drain all the water out of the air line "drops". In the summer you'd be surprised at how much water would come out of a line.

As far as the military I think nitrogen is used because it won't support combustion at altitude. Down here on the surface, that isn't a concern.

rickm · **Posted:** Tue Dec 04, 2007 2:27 am

shimmy wrote:

Compressed air can have a lot of moisture in it. That's why compressors have the drains on the tanks. I had a job, a LONG time ago in a machine shop. My first duty of the day was to go in and drain all the water out of the air line "drops". In the summer you'd be surprised at how much water would come out of a line.

As far as the military I think nitrogen is used because it won't support combustion at altitude. Down here on the surface, that isn't a concern.

Lots of shops will simply empty their air tanks at the end of the day. That will empty any moisture in it and prevent any corrosion of the tanks.

I worked in a lot lf large diesel power power plants that used a lot of compressed air. It was one of the tasks that you did at the beginning of each 8 hour shift, drain the condensation from the air tanks. If I recall, we had to have our air tanks tested every 5 years (?), I can't remember, for structural integrety and corrosion.

When I was talking about nitrogen and aircraft arresting systems.... those are on the ground, on the runways of most fighter bases.

shimmy · **Joined:** Tue Nov 13, 2007 10:20 am **Posts:** 6

rickm wrote:

When I was talking about nitrogen and aircraft arresting systems.... those are on the ground, on the runways of most fighter bases.

Using nitrogen for that application makes perfect sense. You don't want any corrosion in systems where safety would be compromised if any moisture got in there.

rickm · **Posted:** Tue Dec 04, 2007 1:46 pm

Yep, that's why we used oil pumped nitrogen. It's distinguishable by a single black band around the tank it comes in, if I recall correctly.

In my second career (after the military), as a broadcast engineer, we use either dry air or nitrogen to keep pressure on transmission cables and lines to prevent rain from entering antennas and transmission lines.

The first time I saw a broadcaster using nitrogen, it wasn't oil pumped. When I mentioned the oil pumped nitrogen having no moisture in it, they looked at me like I was nuts.

The tranmission lines and antenna systems I maintain here all use compressed air that goes through a dehydrator to remove the moisture from it.

rickm · **Posted:** Sun Dec 16, 2007 3:40 am

Ok, I did some research on using nitrogen in car tires vs compressed air, and here's what I came up with:

Nitrogen has a bit less expansion and contraction during temperature changes than air, or I guess I should say it has a more consistent rate of expansion. Therefore your tires will be more close to their normal tire pressure with nitrogen, than with air.

Nitrogen would have less moisture in it than air does. That's why it expands less than air does.

Also, one cause of tire failure is from oxidation from the inside of the tire. If you fill them with nitrogen, there's less oxygen to cause oxidation inside the tire, and you will get better life out of the tire. This oxidation can cause tire or belt separation. Oxidation along with the moisture from compressed air can cause rims to rust and/or corrode. Rust flakes can get into valve stems and cause problems.

Nitrogen molecules are larger than air molecules, and will diffuse less through porous tires and your tires will maintain their correct pressure longer. Nitrogen diffusion through tires is 30 to 40 percent slower than air.

Nitrogen has better heat dissipation than air, and gives overall better tread wear and tire life because of cooler running tires.

Nitrogen also significantly slows the chemical aging process of the tire's rubber components.

There are a LOT of reasons to fill your car tires with Nitrogen rather than compressed air.

KK · **Posted:** Sun Jan 20, 2008 11:39 pm

My TPS works perfect everyday.

Tire Pressure Warning System

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