Standard air (70 degrees at Sea Level and 0% Relative Humidity) is
13.33 cubic feet per pound. That is at 14.7 Pounds per Square Inch
Absolute (PSIA). That is pressure as related to a vacuum. If you
pressureize an object with air at 32 PSI Guage, that is (14.7+32) PSIA
= 46.7 PSIA. The pressurized air would weigh 3.1769 times as much as
Standard Air. Standard Air weighs .075 pounds per cubic foot. The
pressurized air weighs .075 * 3.1769 = 0.2382675 pounds per cubic foot.
That is a difference of 0.1632675 pounds per cubic foot. So if you
had 5 cubic feet of volume in a tire, the difference in weight would be
5 * 0.1632675 = 0.8163375 or almost a pound heavier. Of course if you
were using something besides Standard Air as a base, the air would have
a different starting weight. For example, colder air would be denser
and would weigh more. If your scale could weigh in increments of 1/10
pound, it would show you the difference.

Stretch