look at the door jamb. it has the recommended pressure on it. Also, our sensors will detect when 1 tire drops below 28 PSI. There is some confusion as to whether our sensors will also light up if 1 tire is vastly different from the rest, and I am not sure. All it says in the service manual is that the light will be set off when a tire(s) drops below 28. I run 37 PSI in my tires, but I'm not on stock wheels.