"How much air should I carry in my tires?
There are three different places tire inflation information can be found. Your owners manual will deal with proper tire inflation, there may be a tag describing proper tire inflation procedures in the drivers door area, either on the door or on the jamb or there is inflation information on the sidewall of the tire. Don’t be surprised if all three don’t match.
The inflation information on the tire will describe the maximum inflation of that tire cold. This is the most that tire should ever be aired to. The owners manual may describe a slightly lower inflation number. Anywhere in between will be fine for any car or SUV or light truck. But remember this:
Using the higher inflation numbers (35-44 psi) will keep the tire cooler, give you better fuel economy but you will sacrifice ride quality. The ride of the car will be harsher than with softer tire pressures.
Using the lower inflation numbers (28-35 psi) will give you a soft, smooth ride but your tires will run hotter and your fuel economy will be between 1-5% less than with fully inflated tires.
I always inflate my customers tires to the maximum inflation figure written on the side of their tire. The only exception is a "Z" rated high performance tire, like ones on a Corvette, Camaro, 300ZX. I do not inflate them to their maximum of 44 psi, but use 35 psi as our upper limit on these tires. Otherwise the ride is way too harsh.