Tom

Tom,

Q I have seen advertisements that promote filling tires with nitrogen

instead of air. They claim better mileage and less air loss (air pressure
maintained). I own a 2006 Jeep Grand Cherokee, and I am considering
having this done. My vehicle also has special valve stems that Jeep calls “tire
pressure monitor and warning signal.” Will it affect that system? I talked to
the Jeep dealer, and they were not sure about the advantage of using nitrogen.
What do you think? Is it worth it?

Jack—New    Brunswick,  New Jersey

Jack,

A Filling the tires of your Jeep Grand Cherokee with nitrogen will not have

a negative effect on the tire pressure monitoring system. I received a service
bulletin from GM stating their position on filling tires with nitrogen. They
are of the opinion that it has no ill effect on GM vehicles at all. So if it’s good
enough for the General, it’s good enough for me!

Nitrogen is an inert gas that is moisture-free. It does not expand and
contract (within the range of temperature changes experienced in tires) like
air does, so tire pressure does not fluctuate significantly. In addition, its
molecules are fatter than that of oxygen; therefore, it doesn’t tend to bleed
out of the tire’s rubber carcass over time, making for much more stable tire
pressures. Maintaining more stable tire pressures should result in better fuel
mileage. You ask me, is it worth it? It isn’t a necessity; it doesn’t make your
vehicle any safer, but if you want to maximize tire life and gas mileage, this
is one more step you can take. Go for it!