OK, here's what I have done for 20+ years.
In the early 80's I attended a police driving instructor school conducted by the Washington State Patrol. This was a week-long school that covered many aspects of police driving, both classroom and hands-on.
Please keep in mind that state patrol and police organizations have a couple of priorities for their cars: safety and handling.
The info they shared with us - and which I have used ever since - is this: you can safely run your tire pressure up to the maximum indicated on the sidewall, while maintaining any front-to-rear-difference indicated by the manufacturer.
Let's break this down, using the example of a passenger vehicle with tires rated 36 PSI maximum on the sidewall. Let's also say that the manufacturer's tire pressure label inside the door jamb says 30 PSI front, 32 PSI rear.
That means to maintain the handling properties designed by the manufacturer, you should run the front tires 2 PSI lower than the rears.
Since the tires are rated 36 PSI maximum, you can safely run the rears at 36 PSI and the fronts at 34 PSI, maintaining the 2 PSI difference recommended by the manufacturer.
If your car manufacturer does not recommend any difference between front and rear tire pressures, you can run them all at the same, higher, pressure of 36 PSI.
(In no case should you allow the tires to run at lower pressures than recommended by the manufacturer. This causes accelerated tire wear and reduced gas mileage by increasing rolling resistance.)
So - what does this achieve?
- It makes the sidewall stiffer, helping the tires respond more quickly to steering inputs - improving handling.
- It may increase gas mileage slightly by reducing rolling resistance.
- It makes the ride somewhat firmer and will let bumps in the pavement be felt inside the passenger compartment.
- It does NOT wear out the center of the tires.
- It does NOT create an unsafe condition with the tires because you are not exceeding the design limits of the tires, even on a hot day.
Now, more and more tires are rated to use 44 PSI maximum. In this case, if you wish to, you could run the fronts at 42 PSI and the rears at 44 PSI. If you do this, you will have a noticeably firmer and harsher ride, but you will also have a perceptible improvement in handling. You probably will gain at least 1 MPG by reducing rolling resistance.
What you do with this information is up to you. You now know the SAFE limits of setting up your tire pressure, and the rest is up to your priorities and how you personally balance handling with ride quality.
My "sweet spot" based on feedback from my hands and rear end is 40 PSI all around in my Murano. Rides well, handles decently, and it's a good setup for my use.