Assuming a 23-25 road tire, if you are using a small 12g CO2, some air with a pump will get you up to a decent pressure. A 16g should get you there w/o needing the pump. Specific PSI numbers would be hard to judge or repeat consistently. You just need to finish the ride. I would not count on being able to save some CO2 for the next flat, it leaks out once punctured.