PSA: Check PSI

[boomerang]

Originally posted by: Howard

Originally posted by: boomerang

Originally posted by: Howard

Originally posted by: boomerang
I don't think what you've experienced is out of the norm.

A tire inflated with air will drop about 1 PSI for every 10 degrees drop in temperature. The converse is true as the temperature rises.

My current car came from the factory with Nitrogen in the tires. I always thought this was a gimmick for a passenger car. I've had the car for 8 months and the tire pressure has not dropped. I also have seen very little change in pressure with temperature changes. I'm sold on Nitrogen.

We just picked up a new car for my wife yesterday and I am thinking of going Nitrogen in those too.

Sorry, but as nitrogen makes up about 78% of air, the pressure/temperature relationship is not significantly different.

Sorry, but you are incorrect.

The rule of thumb is for every 10° Fahrenheit change in air temperature, your tire's inflation pressure will change by about 1 psi (up with higher temperatures and down with lower).

The above is a quote from the following article:

http://www.tirerack.com/tires/...techpage.jsp?techid=73

I crewed on a racing team for approximately 8 years. This fact was readily apparent to me on a regular basis. It's not just the Oxygen content, it's the humidity that goes along with it that affects pressure changes. This is one of the pluses with pure Nitrogen. It has 0% humidity.

Edit: I see bruceb already pointed out the effects of humidity.

You misunderstand me. I said that nitrogen was the major component of air.

As air follows the ideal gas law pretty closely, for a closed volume the pressure is proportional to temperature. Nitrogen is no different, especially as it also behaves like an ideal gas and is pretty much the same as air.

I don't see where you proved me wrong at all.

Whatever floats your boat.

 

[Howard]

I think I'm wrong.

 

[spidey07]

To bring sanity to the thread.

The public service announcement is very sound and all should check their tires regularly. There's some info out there regarding how much pressure a tire actually has lost before it "looks low" and it is a bunch.

 

[yelo333]

Originally posted by: spidey07
To bring sanity to the thread.

The public service announcement is very sound and all should check their tires regularly. There's some info out there regarding how much pressure a tire actually has lost before it "looks low" and it is a bunch.

Agreed, this is mentioned by goodyear in the little booklet that comes with their tires. A tire at 20psi looks very similar to a tire at 30psi. Still, doesn't hurt to visually check your tires before you get in. Just know that you need to check with a gauge, too.

Thanks for the PSA, though. I haven't checked mine for a month or so.