The tire pressure monitoring system doesn't register the individual pressures, it registers a change in pressure. You can set the TPM at any pressure and not get a warning until one or more tires drops some amount below the set point. The proper cold pressures are 29psi on the front and 36psi on the rears. Once those pressures are attained, the TPM should be re-set.
Be cautious about infreqently used, free or coin-op air pumps. They are not too sophisticated, and often have water condensation in their accumulators (storage tanks) and hoses. Before filling the tire it is best to depress the center pin in the air chuck and purge any water. The tire stores' air is dry due to constant compressor usage.