Page 28 - KCRPCA MayJune 2022

TECH
NUTS & BOLTS
IS IT ALL HOT AIR?
SHADE TREE GARAGE WITH A LITTLE HELP FROM MY FRIENDS
TECHNICAL EDITOR KARL WILEN
In the last 10 years, the popularity of using pure nitrogen in tires in- stead of standard air has grown. While in theory it is a good idea,
the end result isn’t exactly perfect either.
Tire stores have found yet another profit center to make a buck, but it might not be the right thing for your tires. You might have noticed the green valve stem caps when you are at a car show looking at cars, or maybe in the parking lot at work, etc. Green valve stem caps are installed to let the person or technician know that nitrogen has been filled into the tires rather than standard air. The air you breathe is the same air that is inflated into your tires through a standard air compressor.
When people think of air, they think we are breathing oxygen. That is true, but only partially. The mixture of air is 78% nitrogen, 21% oxygen, and the remaining 1% is a
various mixture. That’s right....78% nitrogen. Now on a nitrogen tire fill, it is accepted that a 93% nitrogen to air ratio is an acceptable fill. After all, it is nearly impossible to get all of the air out of the tire when you go to fill it with nitrogen (you can’t suck a tire into a vacuum as it is not good for the tire). So you have a 15% increase in nitrogen mixture over standard air.
There have been many reasons nitrogen has been pushed in recent years. Much of it is hogwash spouted off by shops trying to increase their profit margins (just refer back to the air mixtures we just talked about), but some of it has some value. The #1 thing you hear people spout off about nitrogen is that the molecules are larger, so it will not leak out of tires like regular air does. Well, yes, that is true, but if your tire leaks air (it will naturally do so due to permeation of the rubber, let alone other leaks), it will leak nitrogen as
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