Your vehicle has the proper inflation spec on the door sticker for the stock tires. If they are replaced with same size, that inflation level stays the same. If they are replaced with smaller tires it goes up and vice versa. That number assumes a modest load. If you always have an empty vehicle except for the driver, a couple PSI less, or if heavily loaded, a few PSI more until you reach the limit of the tire and then you're probably at the vehicle limit too unless undersized tires were put on.
Note tire wear and adjust from there, if there is wear due to inflation rather than needing an alignment or other suspension problem.
If you just want a number because you don't want to think about it, then 32 PSI.
Don't just inflate a tire to the max trying to get high gas mileage. This will also result in uneven wear and poor traction including stopping distance, as well as poor ride quality if you don't have enough of a load to offset the reduced dampening.
Lastly, the smaller the compressor you use to inflate the tire, the hotter the air is when inflated, so if using a very small compressor, the more air you put in, the more you need to overshoot the target PSI if you check pressure right after inflation rather than waiting for the air to cool down. Usually this is less than 4 PSI, but you can check the pressure again after a half hour and adjust from there.