Regarding your tires losing pressure. Are all four tires losing pressure or just one or two? After you fill them with the correct pressure do they lose more than 1 or 2 psi within a month? Outside temperature can have a big affect on the inflation pressure. If you measured them on a warm day and checked them again on a cold day you could see a drop of 5 psi or more. You will also notice that tire inflation will increase 4 or 5 psi just by driving on them for a few miles causing the tires to warm up. So, inflate your tires to the recommended pressure after the car has been sitting for a few hours. Then check the pressure a few days later before driving the car. If you are still losing pressure you either have a small hole in the tire, poor sealing between the tire bead and the wheel, or a leaking valve stem.