There is a direct relationship between "slip angle" which affects handling, tire wear, and ride quality. For a particular vehicle, there is usually a sweet spot, but that can vary depending on the actual tire on the car. The car companies have a tire pressure in mind which is a good compromise based on what they are supplying as OEM , but if you go up a rim size and width and fit a "performance" tire with a stiff sidewall and additional belts, it may be well off. The companies can't control what you replace OEM with. For example, overinflation usually affects a wider tire sooner than a narrow one. Radials don't telegraph underinflation to the driver as quickly.
In the racing world, tire pressure is set by using a "tire pryometer" which measures temps across the tread. The techs shoot for even heating. Hot spots point to inflation problems and/or alignment issues. We can't do that with a daily driver, so using an accurate gauge and getting a feel for adjustments is the best we can do. Don't just assume that more air is better.