I got some Yoko ES100 tires 205/60R14 for my 14x6.5" rims about a week and a half ago. I checked the cold air pressure the day after, and it was about 35 psi all around. I've driven the car about 130 miles since. Today, I checked the pressure again and they're all in the 30-32 range. What could've happened? Is it possible that all 4 tire beads weren't seated correctly on the rims? Also, these tires have fancy metal valve stem caps-- are these more prone to leak air?