Originally Posted by

**bluefoxicy**
700c tire is 622mm diameter times pi gives circumference, times roughly a radius of 14mm (for 28mm internal diameter) for a circular profile of the internal air space, squared, times pi again, gives the total volume, around 0.0425 cubic feet.

0.0425ft^3 * 0.515 lb/ft^3 at 80F at 90PSI gives 0.219 pounds or around 3 1/3 ounces of air in 700c x 32 tires at 90PSI at 80F.