1. The retail tire pressure gauges you buy for a few dollars have a wide tolerance range. You may think you are running "X" psi, but that does not mean you really are. I have several tire gauges and they vary by 4-5 psi among them.
2. The Continental tires on my Mustang have a tendency to flat-spot when they sit. One tire has one spot that is the worst, but when I first get on the freeway after it sits more than a day, it has a bit of a shake until the tires warm up.
3. When I first put those Continental tires on the car, they rode poorly for about a thousand miles until the tires sort of broke in. They ride and feel a lot better now at 10k miles than they did when new.
2. The Continental tires on my Mustang have a tendency to flat-spot when they sit. One tire has one spot that is the worst, but when I first get on the freeway after it sits more than a day, it has a bit of a shake until the tires warm up.
3. When I first put those Continental tires on the car, they rode poorly for about a thousand miles until the tires sort of broke in. They ride and feel a lot better now at 10k miles than they did when new.