You might carry 100 psi of air in all your tires, but does that add anything to your load? Let's look at the numbers: The air chamber of a typical 11R22.5 radial holds about 30 gallons of air.

At a normal temperature of 72 degrees, the air inside would weigh less than 5 ounces. But, if you're running at 100 psi, you're putting nearly 8 times as much air into the tire as at normal atmospheric pressure.

It works out to a little over 2 pounds of air (by weight) in every tire, or about 42 pounds for 18 tires.

Now, what if you could put helium in your tires? You can't, of course, because it would diffuse through the rubber so fast you wouldn't be able to maintain the correct pressure. Still, if you could, how much weight could you save?

Well, the same amount of helium in all 18 tires would weigh about 6 pounds. That would get you about 42 - 6 = 36 pounds of "lift." So, needless to say, our photo is a fake.