I don't think a few psi make any difference. I have used my li'l red car with, what turned out later, 25 psi and pumped it up to as much as 32psi. But I mostly drive around West Seattle and occasionally on the freeway where maybe 70 is as fast as I go. Tire pressure is not all that important as long as it's not flat. A visual inspection is all it takes. My car has stood around for many years and the tires have developed flat spots. I can sometimes feel them on a real smooth road and it seems, they have become less pronounced from when I first got the car, because I drive it more. The automatic also seems to shift a lot smoother,especially from 2 - 3. But I got a rock into the windshield on the freeway. It's too bad. Now there is a defect the size of a dime.