a. There are two main variables that will determine that number: Tire size and width.
b. There are two main scenarios that a cyclists usually encounter: (1) Reduced air pressure due to unused bike for couple of weeks. (2) Slow leakage of air due to puncture that will eventually cause a flat tire. In these cases, we need an emergency, highly pressured, inflation, so we could reach our final destination (return home safely, get on time to class or work, and even arrive less sweaty to a romantic date). The RideAir will help you manage both situations.
For the number of Full tires the RideAir can provide, see table above.