LittleWyvern.com

Cold Pressure

People make fun of me a lot for being a bit aloof - naive, if you will. (Mostly they just call me an idiot.) I freely admit that from time to time I can be a smidge out of touch with the Real World, but I swear… sometimes it really isn’t my fault.

This afternoon I drove over to a nearby gas station because one of my front tires was low on air. I have a deep-rooted anxiety about putting air into car tires, my irrational (but entirely possible!) fear of the tire violently exploding and killing me enough to avoid the process at almost all costs. Usually - and this is a little bit embarrassing to admit - when my tires need air I simply go and get an oil change. Checking and setting tire pressure is part of the Jiffy Lube signature service.

Unfortunately, having recently had service on my car it would have been ridiculous to get an oil change. I would have to do this myself…

I know just about all that I care to know about cars, which is to say very, very little. Somehow, somewhere I came to know that the recommended tire pressure for your particular vehicle can be found on a sticker on the inside of your driver-side door. I also know how to use a pressure gauge so all that should be left for me to do is to put the air in the tire, matching the pressures to the numbers on the sticker, and cross my fingers that I might escape the process with my life. Easy enough.

Or so I thought…

Here is a picture of a Tire Pressure Sticker very similar to the one in my own car.

Looking at my sticker I quickly found the values for the recommended “Cold Tire Inflation Pressure.” But, and I’m sure you can guess where I am going with this, I couldn’t find any recommended pressure values for warm weather. It is 110 degrees in Las Vegas, presumably even hotter on the concrete, but the sticker gave no indication as to what the pressures should be in this heat. Instead, the sticker referred me to my car’s owner’s manual. I dug into my glove compartment and after a few minutes of searching I found my answer: I am an idiot.

“Cold Tires” simply mean tires that have been parked for at least three hours. Apparently when you drive your tire pressure rises by a few PSI. An accurate reading can only be taken once the tires have normalized - or gone “cold.”

As I read through the owner’s manual my initial sense of embarrassment quickly turned to anger. What kind of moron would use the word “cold” in this context? I find it impossible to believe that I am the only person who has been confused by this ridiculous choice of terminology, especially because in this context the use of Cold and Hot pressure values makes complete sense. It should be common knowledge to anyone who has taken a basic chemistry class that the volume of a gas is directly related to its temperature, and that pressure is directly related to volume. You should have to put more air into your tires in the winter… that’s just physics, people.

But, no. Once again I am left playing the idiot in life’s little play. I just want to take a moment and say “Thank You!” to all the automotive engineers, mechanical engineering majors, and even the assembly line workers (”Yo, Daryl”) who have conspired to waste ten minutes of my afternoon. It was awesome.