No. You can just add to the existing air in the tires. Since you want a specific PSI, be sure you have either a gauge built in to you pump or a seperate tire gauge.
Pressure is constant weather you add air or not. If you don't have a gage on the floor pump go by pressing your thumb on the side wall. You can pretty much tell the correct pressure my feel after you use a gage a few times.
Pressure is constant weather you add air or not. If you don't have a gage on the floor pump go by pressing your thumb on the side wall. You can pretty much tell the correct pressure my feel after you use a gage a few times.
