Recommended tire pressure is 30 psi. On long route, your tire pressure increase. So, in summer always fill up your tire in morning and only 30 psi front and rear.
Reason:
In the morning when your car is in shade, the tire temperature is normal so when air will be filled then its density will be more at 30 psi. But, as you will travel the temperature of tire will increase which will decrease density and increase pressure inside tires. You can check it yourself after long journey that pressure inside tires will increase.