I worked in the tire industry for a tire manufacturer in the warranty department for several years, so I do actually have a solid background in this.
Any given tire can be used on any number of different vehicles. These vehicles will almost certainly have a variety of curb weights, max weights, and front/rear weight distributions (within a certain range, of course, if the same tire is used) and different drive systems (front, rear. AWD, etc.). The tire manufacturer may know SOME of the vehicles the tire will be used on when when they design the tire and start manufacturing it, but the tire manufacturer by no means knows ALL of the vehicles the tire will be used on during the manufacturing lifecycle of that particular model/size/speed rating. So, all a tire manufacturer can do is provide information on what it knows for sure - the maximum load the tire can support AND THE TIRE PRESSURE NEEDED IN ORDER TO SUPPORT THAT MAXIMUM WEIGHT. That is the psi that is molded on the sidewall of the tire. It is not a recommended pressure, it is the pressure that is necessary for the tire to support it's maximum weight.
Vehicle manufacturers know what the curb weight of their vehicles are. They know what the maximum weight of their vehicles are. They know what the front/rear weight balance is. They know whether the vehicle is front or rear wheel drive. They know what tire size and speed rating is original equipment on the vehicle. Therefore, it is for the vehicle manufacturer to determine the correct PSI for the front and rear tires so that those tires will support the appropriate weight on the front and rear of the vehicle.
There is a danger is both under-inflating and over-inflating tires on any vehicle. Underinflation will most certainly lead to a buildup of heat at higher speeds and produce much higher failure rates as a result (tread separations, sidewall separations, sidewall blowouts, etc.).
Overinflation will often result in additional cabin noise, as well as inferior cornering, stopping, acceleration and wet performance. Both conditions will likely produce uneven and premature tire wear. Over-inflation in particular will produce premature wear on the center 1/3 of the tread. This can be especially dangerous in wet weather because the car owner may look at the outer tread, see there is sufficient depth to drive safely, however the center of the tread could be almost fully worn, and because the tire is over-inflated, the center of the tread is supporting the most weight and making the most consistent contact with the road.
If driving in wet weather, if the center of the tread does not have sufficient depth to evacuate the water on the road from the tire's surface, this will result in hydroplaning.
The point is - follow the recommended PSI from the vehicle manufacturer, found inside the driver's door jam - not the psi molded onto the sidewall of the tire. Not doing so will most certainly void your tire warranty.
In my years working for a tire manufacturer, I found myself in a position to of having to deny many warranty claims because the owner 'followed the psi molded onto the sidewall of the tire' and not the vehicle manufacture's recommendations, and damage to their tires resulted.
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