After many years as a car enthusiast with some competition experience, I do not advocate inflating tires to the rated maximum unless the load conditions
call for this, because overinflation can hurt traction, make the ride harsher, and cause uneven tire wear (excessive centre wear). On the other hand, the tire pressures recommended by the vehicle manufacturer (the door sticker numbers) may be too low for optimal handling or wear, since they consider ride comfort. I consider the pressure given on the vehicle sticker a minimum, the one in the sidewall marking a maximum, and inflate to suit conditions.
The most suitable pressure depends on the tire type and size, and the load. With very wide tires on light
cars, the appropriate pressure is low; with moderately sized tires on heavily loaded vehicles such as trailers, the most appropriate pressure might be quite high. The passenger-type tires on my Boler
(P205/75R14) are being used very near their load limit (1350 lb after 10% derating), and thus require inflation pressure right at their rating (35 PSI); if they were rated for higher pressure, I would use it, and would expect better control, less wear, and less rolling drag. New tires are planned for this year...
In practice, I drive hard enough that I keep front tire pressures in my cars near the maximum. When I was participating in autoslalom competition, I exceeded the front tire rated limit, to keep the tires from rolling over onto their sidewalls. This is not a normal driving scenario, especially while towing.
On the Sienna, I generally run the Toyota recommended pressures, except to inflate the rears to the rated maximum for towing. The additional lateral stiffness of the higher pressure is good for control. While the sticker pressure will ensure adequate load capacity (assuming that the axle
limit is observed) a little more load capacity margin seems like a good idea when loading the rear axle
to near its limit. Having said this, I don't have enough towing time to judge whether my chosen pressures have proven to be suitable.