Why would a tire that has no nails or punctures keep losing air pressure?
Tires can leak in several places. Valve stems are one common place, particularly if the stem cap is missing. Another area of leakage is corrosion around the tire bead area of the wheel. This can leak a small amount in several places and be difficult to find. Leakage that occurs in new tires can be caused by a defect in the tire. Not common but some tires just leak through the rubber. This is a defect and such a tire will often be replaced at no cost. Finally, wheels can sometimes have porosity and cause a leak. This is normally diagnosed by switching the tire to another wheel and see if the leak stays with the tire or moves with the wheel.
