[Tonyr]

The info on the door jam says that cold air pressure should be 30 psi. The tires I have say 51 psi max air pressure. I usually check the pressures once per week. I air them up to about 40 psi and they look fine. If I was to take them down to 30 psi as recommended by GM, the tires look very low. Am I hurting the tires by going up to 40?